CA2248923A1 - Rate monitor for a displacement system utilizing the power demand of the prime mover of the system to provide the flow rate data of the material being displaced - Google Patents
Rate monitor for a displacement system utilizing the power demand of the prime mover of the system to provide the flow rate data of the material being displaced Download PDFInfo
- Publication number
- CA2248923A1 CA2248923A1 CA002248923A CA2248923A CA2248923A1 CA 2248923 A1 CA2248923 A1 CA 2248923A1 CA 002248923 A CA002248923 A CA 002248923A CA 2248923 A CA2248923 A CA 2248923A CA 2248923 A1 CA2248923 A1 CA 2248923A1
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- Canada
- Prior art keywords
- power demand
- flow rate
- prime mover
- monitor
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
- G01F1/80—Direct mass flowmeters operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G11/00—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers
- G01G11/14—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers using totalising or integrating devices
- G01G11/16—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers using totalising or integrating devices being electrical or electronic means
- G01G11/18—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers using totalising or integrating devices being electrical or electronic means using digital counting
Abstract
A flow rate monitor (R) for indicating the amount of material being displaced in a displacement system having an electric motor (2) as a prime mover, comprises a power demand monitor (20) for being operably connected to the prime mover; a programmable controller (24) operably connected to the power demand monitor, the controller being adapted to convert the data from the power demand monitor and convert it to flow rate data using a linear relationship between the power demand of the prime mover and the flow rate of the material; and an indicator (36) for indicating the flow rate of the material.
Description
WO97/34130 PCT~S97/03477 RATE MONITOR FOR A DI~PL~C~N~T 8YSTEM UTILIZING THE
POWER DEMAND OF THE PRIME MOVER OF THE ~Y~ M TO PROVIDE
THE F~OW RATE DATA OF THE NAT~T~T~ BEING DI8PLACED
This is a regular application of provisional applications serial nos. 60/013,175 and 60/016,612, filed on March 12, 1996 and May 1, 1996, respectively, which are herein incorporated by reference.
FIELD OF THE INVENTION
The present invention generally relates to an apparatus and a method of generating flow rates for displaceable materials in a displacement system using conveyor belt, augers, bucket elevators, horizontal screws ~ dedicated pneumatic conveyors, and the like, by utilizing the power demand of the prime mover of the system to provide the flow rate data of the material being displaced.
BACRGROUND OF THE lNV~ lON
Prior art methods of measuring displaceable material, such conveyed crushed rock, coal, feed, etc, augered material such as powder, seeds, cement, etc, and liquid material such as water, oil, etc, are limited to conveyor belt and gravimetric scales which are calibrated to read in unit weight per unit time, or liquid flow rate meters reading in units of li~uid measure per unit time, etc. The prior art methods strive for accuracy through WO97134130 PCT~S97/034M
sophisticated electronic components in precision electro-mechanical interaction, such as conveyor scales with electronic load cells, sensing physical movement in relation to the amount of material on the conveyor scale, or rotary impellers coupled to a sensor for liquids, or electronic physical displacement sensors mechanically coupled to an impacting surface measuring the rate of material flowing through a pipe, etc, resulting in the desired unit of measurement.
Prior art conveyor belt scales typically consists of a scale carriage with load cells and/or linear ~ differential transformers and associated electronic circuits, a conveyor motion or speed sensor, and several idlers before and after the scale carriage. Installation of a conveyor belt scale generally requires mechanics and welders to mount the scale to the conveyor frame, ~ electrician to run conduit and wires from the main panel in the control room to the scale, and trained factory technicians to inspect and configure the scale to the specific application. Thus, the installation process can be quite involved, including significant installation work, lengthy field wire runs conveyor, frame modification, weigh bridge installation, mechanical line-up for accuracy, additional sensor mounting and associated wires for conveyor speed, etc.
Conventional belt scales require almost constant calibration and trimming to account for variations in material density, conveyor belt carriage alignment, conveyor belt centering, wedged rocks in-between the scale WO97/34130 PCT~S97/03477 measuring beams, etc., to obtain material flow rate data within the error tolerance of the scales. Maintenance personnel would need basic understanding of the conveyor belt system, scale carriage, load cell, speed sensor, electronics associated, etc., in addition to being familiar with voluminous user manuals. Thus, prior art systems are sophisticated electro-mechanical systems requiring highly trained personnel for installation and maintenance.
There is therefore a need for flow rate monitor that replaces complicated belt scales and requires no expertise on conveyor scales and their associated load ~ cells, linear voltage differential transformers, scale beams, etc. and minimizes a large portion of the installation headaches that generally accompany the industrial belt scales.
OBJECT8 AND SUMMARY OF THE l~.v~ ON
It is an object of the present invention to provide a rate monitor for displaceable materials that involves no electronic load cells, linear voltage differential transformers (LDT), etc, mechanical impellers, switches, nor any kind of electro-mechanical interaction.
It is still another object of the present invention to provide a rate monitor for conveyed materials ..
that eliminates the use of scale carriages fitted into the conveying system.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates the need for conveyor frame modification or W O 97/34130 PCTnUS97tO3477 the need to cut into a pressurized pipe to bolt a flow sensor or gravimetric scale.
It is yet another object of the present invention to provide a rate monitor for conveyed materials that eliminates running lengthy field wiring for system power or for signal cables back to the main control room.
It is another object of the present invention to provide a rate monitor that minimizes the concern with a conveyor angle of inclination which would interfere with scale accuracy or the minimum number of idlers before and after the typical conveyor scale installation.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates mechanical motion sensors.
It is yet another object of the present invention to provide a rate monitor for conveyed materials that provides system overburden/overload alarm.
It is another object of the present invention to provide a rate monitor that is relatively easy to install, thereby minimizing the installation-intensive problems associated with prior art belt scales.
In summary, the present invention provides a flow rate monitor for indicating the amount of material being conveyed in a conveying system having a prime mover, comprising power demand monitor for being operably connected to the prime mover; a programmable controller operably connected to the power demand monitor, the controller being adapted to convert the data from the power demand monitor and convert it to flow rate data using a WO97t34130 PCT~S97/03477 linear relationship between the power demand of the prime mover and the flow rate of the material; and an indicator for indicating the flow rate of the material.
The present invention also provides a method for measuring the amount of material being displaced in any displacement system with an electric motor as a prime mover, in a substantially linear region of operation where the power demand of the prime mover is linearly related to the flow rate of the material, comprising the steps of calibrating the system to establish the linear relationship of the power demand to the flow rate; measuring the power demand of the prime mover; and calculating and displaying the flow rate of the material being conveyed from the linear relationship. In a system where the power demand is not linearly related to the flow rate of the material, the power demand is approximated by a series of linear zones ~ whereby the power demand is linearly related to the flow rate in each zone.
These and other objects of the present invention will become apparent from the following detailed description.
BRIEF DESCRIPTIONS OF THE DRAWINGS
Figure l is a block diagram of a flow rate monitor made in accordance with the present invention.
Figure 2 is a graph of the rate flow against the power demand of the prime mover for a linear system.
Figure 3 is a graph of the rate flow against the power demand of the prime mover for a semi-linear system.
WO97/34130 PCT~S97/03477 Figure 4 is a graph of the rate flow against the power demand of- the prime mover for a non-linear system.
Figures 5A-5N is a flow-chart of a process in accordance with the present invention for determining the flow rate in terms of the power demand of the prime mover.
Figures 6A-6C are graphs of the flow rate against the power demand of the prime mover when shifted by an AUTO-TARE routine in accordance with the present invention.
Figure 7 is a flow-chart of a process in accordance with the present invention for automatically recalibrating the pulse output of the rate monitor to ~ correspond to the rate output.
DETAILED DESCRIPTION OF THE INVENTION
It is common knowledge that power used by an electric motor to perform work is a product of the voltage, current, cosine of the phase angle between the voltage and current, known as power factor, and efficiency of the motor. Efficiency is defined as the output power divided by the input power. Where the line voltage of the system is relative constant and the current varying linearly in relation to the load impressed on the motor, power will be fairly linear and will used in the present invention as an indicator of the physical load on the system. The efficiency of the electric motor is fairly constant at 15%
of full load or greater. Thus, monitoring output or input horsepower is immaterial when the motor is loaded to greater than 15% of full load.
WO97/34130 PCT~S97/03477 Power consumed by an electric motor that is operably connected to a mechanical system displacing the material is then directly proportional to the load on the motor and is a reliable indicator of how much material the conveying system is transporting at any given time.
The present invention will employ this relationship between power consumed by an electric motor and the amount of material being displaced. The load on an electrical motor relates to the amount of work that it has to perform or deliver, varying from a minimum no-load condition to a maximum full-load condition. The power of ~ the electric motor is translated into output horsepower by the following formula, H~rseP~Weroutput = WattS~otor input * EffiCienCy/746.
Therefore, the more horsepower required to transport material, the more power is required from the ~ electrical system; or the more material being transported, the more power required to do the work. Hence, when operably connected to a mechanical system, power consumed and the resulting horsepower delivered by an electric motor will be directly related to the amount of material in the system from no-load to full-load, which can be represented in accordance with the present invention, by a straight line graph.
The present invention will now be described using the example of a conveyor belt system. However, it should be understood that the present invention would be equally applicable to bucket elevators, horizontal screws, single system/dedicated pneumatic conveyors, very short length WO97/34130 PCT~S97/03477 conveyors, or any system utilizing an electric motor or prime mover whose power output parameters can be monitored to provide a measure of the amount of materials being conveyed per unit of time.
A rate monitor R made in accordance with the present invention is disclosed in Figure l. An electric motor 2 is operably connected to a conveyor belt (not shown) that is used to convey displaceable materials, such crushed rock, coal, feed, etc. An electric panel 4 provides a three-phase power to the motor 2 through wires 6 with overload elements 8. A motor starter lO is provided ~ for starting or stopping the motor 2. The motor 2 has an output shaft 12 that is mechanically coupled to the conveyor belt.
The wires 6 are tapped at 14 and fed a voltage sensor 16. Current sensors 18 are provided to measure the ~ current flowing through the lines 6. The voltage and current data from the sensors 16 and 18 are combined in a standard power measuring device 20 whose output signal 22 corresponds to the power demand of motor 2.
The output 22 is fed to a programmable device 24 that converts the power data from the device 20 into a flow rate date for the materials being conveyed. An example of ~he power sensing unit is available from Load Controls, Inc., lO Picker Road, Sturbridge, Massachusetts 01566, Model PH-3A Powercell.
The programmable device 24 can be an electronic circuit, programmable logic controller, embedded memory card or any electronic device that is programmed in WO97/34130 PCT~S97/03477 _g_ accordance with the present invention to process the power data into flow rate data. An example of the programmable device 24 is a programmable logic controller available from PLC Direct, Model D2-04B, 305 Hutchinson Road, Cumming, Georgia 30130.
An operator interface terminal (OIT) 26 is operably connected to the device 24 and provides a means for the user to input the necessary parameters to the device 24 and to display data and messages during operation of the monitor R. The operator interface terminal 26 is a standard device, such as Model PV1000, available from PLC
~ Direct.
At least one output device is connected to the programmable device 24 to obtain a readout of the material flow rate. A flow rate display 28 converts the flow rate output signal 30 to weight per unit time, such as ton/hour, ~ pounds/minute, etc. A process control computer system 32 can also be connected to the device 24 to monitor and store the flow rate output 30. A process loop controller 34 can also be connected to the device 24 so that depending on the value of the flow rate output signal 30, certain valves, pumps, etc, can be operated or otherwise controlled by the controller 34.
A totalizer accumulator counter 36 can also be ..
connected to the device 24 through an integrator output signal 36 which can be in the form of a pulse train, wherein each pulse corresponds to a unit weight or fraction thereof. An alarm 40 is connected to the device 24 to indicate when a high or low power demand limit has been WO97134130 PCT~S97/03477 reached. A high setting alarm would indicate system overload while-a low setting alarm would indicate some mechanical problems, such as mechanical disengagement of the motor with the conveyor belt.
The programmable device 24 will now be described in detail.
The monitor R approximates the relationship of the electrical motor power output or power demand of the motor 2 to the flow rate of material being displaced by the conveyor with a series of connected straight line segments, dividing the power curve into multiple zones, each zone ~ being represented by a linear equation. The present invention will be described using up to three zones but it should be understood that a greater number of zones can also be used.
Referring to Figure 2, a single zone model is disclosed, using the single straight line equation, Y = MX + B, where B is the Y intersect at Xl = 0, M is the rate of change or slope of the line, or M=(Y2-Y,)/(X2-xl)-In Cartesian coordinates, the Y axis represents the horsepower output or power demand of the electric motor 2 and the X axis represents the flow rate of the material being conveyed or displaced by the conveyor belt.
The value of the slope M is derived from the proportional relationship between an actual measured change of displaceable material in the system and the respective change in power output by the electric motor 2 to move, W O 97/34130 PCTrUS97/03477 convey, transport, displace, or process the increase or decrease in the displaceable material. The value of X
represents the material flow rate in units of weight or volume per unit time, such as tons/hour, gallons/hour, pounds/minute. etc.
The Y intersect or B is the minimum no-load power output of the motor or prime mover operating or moving the mechanical displacement or conveying system without any material actually going through it. The Y intersect also sets the area beyond which the motor efficiency remains fairly constant. The value of B is generally greater than ~ 15% of the motor full load capacity. The efficiency curve of the motor is substantially linear beyond the 15% point.
Accordingly, the horsepower output of the electric motor and the flow rate of the material being conveyed in a single zone system may be represented by the ~ following equation, Y = M*X + B, or X = (Y-B)/M.
Referring to Figure 3, a two-zone model is disclosed, approximated by two straight line segments represented compositely by the equations, Y = MaX + B, or X = (Y-B) /Mal where Ma=(Y2-Y1)/(X2-x1)/ Y1<Y~Y2, Y1 B~ and Y = Mb(X-X2)+y2, or X = (Y-Y2~ /Mb + X2~
where Mb=(Y3--Y2)/(X3 X2) and Y2<Y<YMAX.
W O 97/34130 rcTnusg7/o3477 ' -12-Referring to Figure 4, the relationship between horsepower output of the electric motor 2 and the flow rate of the material being displaced, in a system that is not substantially linear, is represented by a three-zone system approximated by three straight line segments represented by the following equations, Y = MaX + B, or X = (Y~B)/Ma, where Ma=(Y2-Y,)/(X2-x1)~ Y1<Y~Y2, Y1 B, y = Mb(X X2)+Y2, or x = (Y--Y2)/Mb + X2~
- where Mb=(Y3-Yz)/(X3~x2)~ Y2<Y<Y3, and Y = (X-x3)/Mc + Y3, or X = (Y-Y3)/Mc + X3~
where MC=(Y4-Y3)/(X4-X3)~ Y3~Y<YMAX-The three-zone system can be extended to a n-zone system, where n is any integer, to approximate non-linear displacement systems to n linear zones. The larger n is, the better will be the approximation. Each zone is calibrated as described for the single-, two-, and three-zone systems above. In general, the flow rate as related to the power demand is given as follows, X=(HP-Yn)/Mn, where n is the number of zones, M=(Yn+1-Yn)/(Xn~1-Xn) is the slope of the n-th line segment, HP is the horsepower demand of the electric motor, X is the flow rate, Yn is the horsepower at the Xn belt cut, and W O 97134130 PCTrUS97/03477 Yn+1 is the horsepower at the Xn~1 belt cut.
As a result of the mechanical system transporting, processing or otherwise conveying the material in which the electrical motor is the prime mover, the power output of the prime mover may be related to the quantity or amount of load or material being conveyed by the above equations. The present invention translates the electrical load on the motor to the amount of material, in weight units per time, that the system is conveying or transporting.
The device 24 includes a main system program ~ (MSP) that utilizes the linear equations disclosed in Figures 2, 3 or 4 to provide flow rate data from the monitored power output of the electric motor 2.
For a linear system, the equation disclosed in Figure 2 is used. The slope M of the equation is ~ determined from the value of Y1 or B, which is the system-no-load power demand, and the actual power output of the electric motor under load and actual measurements of the material being displaced by the conveying system. Once the slope is determined, the material flow rate in weight/time or volume/time is determined by the equation from the known power output of the motor.
For a non-linear system, the equations disclosed in Figure 3 or 4 are utilized, as appropriate, to approximate the non-linearity of the system.
The system-no-load power demand B advantageously offsets any changes in the power requirement of the system caused by normal or accelerated wear and tear on the mechanical parts of the displacement system, or the wetting and drying of conveyors operating in wet weather conditions, or when the mechanical components that have aged through the years are replaced with new parts that cause a decrease or lighter load to be impressed on the electric motor of the system. The MSP also advantageously uses the system-no-load data to detect abnormal mechanical system conditions, indicating conveying system failure, such as mechanical system failure with the conveyor belts, gear box failure, etc, thereby advantageously replacing the need for conventional mechanical or electro-~ech~nical conveyor motion sensors (sometimes called zero speed switches, rotary sensors, belt sensors, etc) that are typically used in the prior art systems.
The MSP advantageously utilizes the full-load data in the single-, two-, and three-zone system of the ~ power output of the electric motor to detect abnormal conditions indicating mechanical system failure, jam, or an electrical overburden that is not within the operating range of the electrical system.
The MSP will now be described in detail in reference to Figures 5A-5N.
The following parameters are entered into the MSP
via the terminal 26 for each specific application:
1. Maximum horsepower of the electric motor used.
2. Time in seconds for the system to stabilize under no load to provide the system-no-load power demand (approximately 1-2 belt revolutions for belt conveyors and WO97/34130 PCT~S97/03477 bucket elevators, or the time it takes for the material to move from input to output for a horizontal screw).
POWER DEMAND OF THE PRIME MOVER OF THE ~Y~ M TO PROVIDE
THE F~OW RATE DATA OF THE NAT~T~T~ BEING DI8PLACED
This is a regular application of provisional applications serial nos. 60/013,175 and 60/016,612, filed on March 12, 1996 and May 1, 1996, respectively, which are herein incorporated by reference.
FIELD OF THE INVENTION
The present invention generally relates to an apparatus and a method of generating flow rates for displaceable materials in a displacement system using conveyor belt, augers, bucket elevators, horizontal screws ~ dedicated pneumatic conveyors, and the like, by utilizing the power demand of the prime mover of the system to provide the flow rate data of the material being displaced.
BACRGROUND OF THE lNV~ lON
Prior art methods of measuring displaceable material, such conveyed crushed rock, coal, feed, etc, augered material such as powder, seeds, cement, etc, and liquid material such as water, oil, etc, are limited to conveyor belt and gravimetric scales which are calibrated to read in unit weight per unit time, or liquid flow rate meters reading in units of li~uid measure per unit time, etc. The prior art methods strive for accuracy through WO97134130 PCT~S97/034M
sophisticated electronic components in precision electro-mechanical interaction, such as conveyor scales with electronic load cells, sensing physical movement in relation to the amount of material on the conveyor scale, or rotary impellers coupled to a sensor for liquids, or electronic physical displacement sensors mechanically coupled to an impacting surface measuring the rate of material flowing through a pipe, etc, resulting in the desired unit of measurement.
Prior art conveyor belt scales typically consists of a scale carriage with load cells and/or linear ~ differential transformers and associated electronic circuits, a conveyor motion or speed sensor, and several idlers before and after the scale carriage. Installation of a conveyor belt scale generally requires mechanics and welders to mount the scale to the conveyor frame, ~ electrician to run conduit and wires from the main panel in the control room to the scale, and trained factory technicians to inspect and configure the scale to the specific application. Thus, the installation process can be quite involved, including significant installation work, lengthy field wire runs conveyor, frame modification, weigh bridge installation, mechanical line-up for accuracy, additional sensor mounting and associated wires for conveyor speed, etc.
Conventional belt scales require almost constant calibration and trimming to account for variations in material density, conveyor belt carriage alignment, conveyor belt centering, wedged rocks in-between the scale WO97/34130 PCT~S97/03477 measuring beams, etc., to obtain material flow rate data within the error tolerance of the scales. Maintenance personnel would need basic understanding of the conveyor belt system, scale carriage, load cell, speed sensor, electronics associated, etc., in addition to being familiar with voluminous user manuals. Thus, prior art systems are sophisticated electro-mechanical systems requiring highly trained personnel for installation and maintenance.
There is therefore a need for flow rate monitor that replaces complicated belt scales and requires no expertise on conveyor scales and their associated load ~ cells, linear voltage differential transformers, scale beams, etc. and minimizes a large portion of the installation headaches that generally accompany the industrial belt scales.
OBJECT8 AND SUMMARY OF THE l~.v~ ON
It is an object of the present invention to provide a rate monitor for displaceable materials that involves no electronic load cells, linear voltage differential transformers (LDT), etc, mechanical impellers, switches, nor any kind of electro-mechanical interaction.
It is still another object of the present invention to provide a rate monitor for conveyed materials ..
that eliminates the use of scale carriages fitted into the conveying system.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates the need for conveyor frame modification or W O 97/34130 PCTnUS97tO3477 the need to cut into a pressurized pipe to bolt a flow sensor or gravimetric scale.
It is yet another object of the present invention to provide a rate monitor for conveyed materials that eliminates running lengthy field wiring for system power or for signal cables back to the main control room.
It is another object of the present invention to provide a rate monitor that minimizes the concern with a conveyor angle of inclination which would interfere with scale accuracy or the minimum number of idlers before and after the typical conveyor scale installation.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates mechanical motion sensors.
It is yet another object of the present invention to provide a rate monitor for conveyed materials that provides system overburden/overload alarm.
It is another object of the present invention to provide a rate monitor that is relatively easy to install, thereby minimizing the installation-intensive problems associated with prior art belt scales.
In summary, the present invention provides a flow rate monitor for indicating the amount of material being conveyed in a conveying system having a prime mover, comprising power demand monitor for being operably connected to the prime mover; a programmable controller operably connected to the power demand monitor, the controller being adapted to convert the data from the power demand monitor and convert it to flow rate data using a WO97t34130 PCT~S97/03477 linear relationship between the power demand of the prime mover and the flow rate of the material; and an indicator for indicating the flow rate of the material.
The present invention also provides a method for measuring the amount of material being displaced in any displacement system with an electric motor as a prime mover, in a substantially linear region of operation where the power demand of the prime mover is linearly related to the flow rate of the material, comprising the steps of calibrating the system to establish the linear relationship of the power demand to the flow rate; measuring the power demand of the prime mover; and calculating and displaying the flow rate of the material being conveyed from the linear relationship. In a system where the power demand is not linearly related to the flow rate of the material, the power demand is approximated by a series of linear zones ~ whereby the power demand is linearly related to the flow rate in each zone.
These and other objects of the present invention will become apparent from the following detailed description.
BRIEF DESCRIPTIONS OF THE DRAWINGS
Figure l is a block diagram of a flow rate monitor made in accordance with the present invention.
Figure 2 is a graph of the rate flow against the power demand of the prime mover for a linear system.
Figure 3 is a graph of the rate flow against the power demand of the prime mover for a semi-linear system.
WO97/34130 PCT~S97/03477 Figure 4 is a graph of the rate flow against the power demand of- the prime mover for a non-linear system.
Figures 5A-5N is a flow-chart of a process in accordance with the present invention for determining the flow rate in terms of the power demand of the prime mover.
Figures 6A-6C are graphs of the flow rate against the power demand of the prime mover when shifted by an AUTO-TARE routine in accordance with the present invention.
Figure 7 is a flow-chart of a process in accordance with the present invention for automatically recalibrating the pulse output of the rate monitor to ~ correspond to the rate output.
DETAILED DESCRIPTION OF THE INVENTION
It is common knowledge that power used by an electric motor to perform work is a product of the voltage, current, cosine of the phase angle between the voltage and current, known as power factor, and efficiency of the motor. Efficiency is defined as the output power divided by the input power. Where the line voltage of the system is relative constant and the current varying linearly in relation to the load impressed on the motor, power will be fairly linear and will used in the present invention as an indicator of the physical load on the system. The efficiency of the electric motor is fairly constant at 15%
of full load or greater. Thus, monitoring output or input horsepower is immaterial when the motor is loaded to greater than 15% of full load.
WO97/34130 PCT~S97/03477 Power consumed by an electric motor that is operably connected to a mechanical system displacing the material is then directly proportional to the load on the motor and is a reliable indicator of how much material the conveying system is transporting at any given time.
The present invention will employ this relationship between power consumed by an electric motor and the amount of material being displaced. The load on an electrical motor relates to the amount of work that it has to perform or deliver, varying from a minimum no-load condition to a maximum full-load condition. The power of ~ the electric motor is translated into output horsepower by the following formula, H~rseP~Weroutput = WattS~otor input * EffiCienCy/746.
Therefore, the more horsepower required to transport material, the more power is required from the ~ electrical system; or the more material being transported, the more power required to do the work. Hence, when operably connected to a mechanical system, power consumed and the resulting horsepower delivered by an electric motor will be directly related to the amount of material in the system from no-load to full-load, which can be represented in accordance with the present invention, by a straight line graph.
The present invention will now be described using the example of a conveyor belt system. However, it should be understood that the present invention would be equally applicable to bucket elevators, horizontal screws, single system/dedicated pneumatic conveyors, very short length WO97/34130 PCT~S97/03477 conveyors, or any system utilizing an electric motor or prime mover whose power output parameters can be monitored to provide a measure of the amount of materials being conveyed per unit of time.
A rate monitor R made in accordance with the present invention is disclosed in Figure l. An electric motor 2 is operably connected to a conveyor belt (not shown) that is used to convey displaceable materials, such crushed rock, coal, feed, etc. An electric panel 4 provides a three-phase power to the motor 2 through wires 6 with overload elements 8. A motor starter lO is provided ~ for starting or stopping the motor 2. The motor 2 has an output shaft 12 that is mechanically coupled to the conveyor belt.
The wires 6 are tapped at 14 and fed a voltage sensor 16. Current sensors 18 are provided to measure the ~ current flowing through the lines 6. The voltage and current data from the sensors 16 and 18 are combined in a standard power measuring device 20 whose output signal 22 corresponds to the power demand of motor 2.
The output 22 is fed to a programmable device 24 that converts the power data from the device 20 into a flow rate date for the materials being conveyed. An example of ~he power sensing unit is available from Load Controls, Inc., lO Picker Road, Sturbridge, Massachusetts 01566, Model PH-3A Powercell.
The programmable device 24 can be an electronic circuit, programmable logic controller, embedded memory card or any electronic device that is programmed in WO97/34130 PCT~S97/03477 _g_ accordance with the present invention to process the power data into flow rate data. An example of the programmable device 24 is a programmable logic controller available from PLC Direct, Model D2-04B, 305 Hutchinson Road, Cumming, Georgia 30130.
An operator interface terminal (OIT) 26 is operably connected to the device 24 and provides a means for the user to input the necessary parameters to the device 24 and to display data and messages during operation of the monitor R. The operator interface terminal 26 is a standard device, such as Model PV1000, available from PLC
~ Direct.
At least one output device is connected to the programmable device 24 to obtain a readout of the material flow rate. A flow rate display 28 converts the flow rate output signal 30 to weight per unit time, such as ton/hour, ~ pounds/minute, etc. A process control computer system 32 can also be connected to the device 24 to monitor and store the flow rate output 30. A process loop controller 34 can also be connected to the device 24 so that depending on the value of the flow rate output signal 30, certain valves, pumps, etc, can be operated or otherwise controlled by the controller 34.
A totalizer accumulator counter 36 can also be ..
connected to the device 24 through an integrator output signal 36 which can be in the form of a pulse train, wherein each pulse corresponds to a unit weight or fraction thereof. An alarm 40 is connected to the device 24 to indicate when a high or low power demand limit has been WO97134130 PCT~S97/03477 reached. A high setting alarm would indicate system overload while-a low setting alarm would indicate some mechanical problems, such as mechanical disengagement of the motor with the conveyor belt.
The programmable device 24 will now be described in detail.
The monitor R approximates the relationship of the electrical motor power output or power demand of the motor 2 to the flow rate of material being displaced by the conveyor with a series of connected straight line segments, dividing the power curve into multiple zones, each zone ~ being represented by a linear equation. The present invention will be described using up to three zones but it should be understood that a greater number of zones can also be used.
Referring to Figure 2, a single zone model is disclosed, using the single straight line equation, Y = MX + B, where B is the Y intersect at Xl = 0, M is the rate of change or slope of the line, or M=(Y2-Y,)/(X2-xl)-In Cartesian coordinates, the Y axis represents the horsepower output or power demand of the electric motor 2 and the X axis represents the flow rate of the material being conveyed or displaced by the conveyor belt.
The value of the slope M is derived from the proportional relationship between an actual measured change of displaceable material in the system and the respective change in power output by the electric motor 2 to move, W O 97/34130 PCTrUS97/03477 convey, transport, displace, or process the increase or decrease in the displaceable material. The value of X
represents the material flow rate in units of weight or volume per unit time, such as tons/hour, gallons/hour, pounds/minute. etc.
The Y intersect or B is the minimum no-load power output of the motor or prime mover operating or moving the mechanical displacement or conveying system without any material actually going through it. The Y intersect also sets the area beyond which the motor efficiency remains fairly constant. The value of B is generally greater than ~ 15% of the motor full load capacity. The efficiency curve of the motor is substantially linear beyond the 15% point.
Accordingly, the horsepower output of the electric motor and the flow rate of the material being conveyed in a single zone system may be represented by the ~ following equation, Y = M*X + B, or X = (Y-B)/M.
Referring to Figure 3, a two-zone model is disclosed, approximated by two straight line segments represented compositely by the equations, Y = MaX + B, or X = (Y-B) /Mal where Ma=(Y2-Y1)/(X2-x1)/ Y1<Y~Y2, Y1 B~ and Y = Mb(X-X2)+y2, or X = (Y-Y2~ /Mb + X2~
where Mb=(Y3--Y2)/(X3 X2) and Y2<Y<YMAX.
W O 97/34130 rcTnusg7/o3477 ' -12-Referring to Figure 4, the relationship between horsepower output of the electric motor 2 and the flow rate of the material being displaced, in a system that is not substantially linear, is represented by a three-zone system approximated by three straight line segments represented by the following equations, Y = MaX + B, or X = (Y~B)/Ma, where Ma=(Y2-Y,)/(X2-x1)~ Y1<Y~Y2, Y1 B, y = Mb(X X2)+Y2, or x = (Y--Y2)/Mb + X2~
- where Mb=(Y3-Yz)/(X3~x2)~ Y2<Y<Y3, and Y = (X-x3)/Mc + Y3, or X = (Y-Y3)/Mc + X3~
where MC=(Y4-Y3)/(X4-X3)~ Y3~Y<YMAX-The three-zone system can be extended to a n-zone system, where n is any integer, to approximate non-linear displacement systems to n linear zones. The larger n is, the better will be the approximation. Each zone is calibrated as described for the single-, two-, and three-zone systems above. In general, the flow rate as related to the power demand is given as follows, X=(HP-Yn)/Mn, where n is the number of zones, M=(Yn+1-Yn)/(Xn~1-Xn) is the slope of the n-th line segment, HP is the horsepower demand of the electric motor, X is the flow rate, Yn is the horsepower at the Xn belt cut, and W O 97134130 PCTrUS97/03477 Yn+1 is the horsepower at the Xn~1 belt cut.
As a result of the mechanical system transporting, processing or otherwise conveying the material in which the electrical motor is the prime mover, the power output of the prime mover may be related to the quantity or amount of load or material being conveyed by the above equations. The present invention translates the electrical load on the motor to the amount of material, in weight units per time, that the system is conveying or transporting.
The device 24 includes a main system program ~ (MSP) that utilizes the linear equations disclosed in Figures 2, 3 or 4 to provide flow rate data from the monitored power output of the electric motor 2.
For a linear system, the equation disclosed in Figure 2 is used. The slope M of the equation is ~ determined from the value of Y1 or B, which is the system-no-load power demand, and the actual power output of the electric motor under load and actual measurements of the material being displaced by the conveying system. Once the slope is determined, the material flow rate in weight/time or volume/time is determined by the equation from the known power output of the motor.
For a non-linear system, the equations disclosed in Figure 3 or 4 are utilized, as appropriate, to approximate the non-linearity of the system.
The system-no-load power demand B advantageously offsets any changes in the power requirement of the system caused by normal or accelerated wear and tear on the mechanical parts of the displacement system, or the wetting and drying of conveyors operating in wet weather conditions, or when the mechanical components that have aged through the years are replaced with new parts that cause a decrease or lighter load to be impressed on the electric motor of the system. The MSP also advantageously uses the system-no-load data to detect abnormal mechanical system conditions, indicating conveying system failure, such as mechanical system failure with the conveyor belts, gear box failure, etc, thereby advantageously replacing the need for conventional mechanical or electro-~ech~nical conveyor motion sensors (sometimes called zero speed switches, rotary sensors, belt sensors, etc) that are typically used in the prior art systems.
The MSP advantageously utilizes the full-load data in the single-, two-, and three-zone system of the ~ power output of the electric motor to detect abnormal conditions indicating mechanical system failure, jam, or an electrical overburden that is not within the operating range of the electrical system.
The MSP will now be described in detail in reference to Figures 5A-5N.
The following parameters are entered into the MSP
via the terminal 26 for each specific application:
1. Maximum horsepower of the electric motor used.
2. Time in seconds for the system to stabilize under no load to provide the system-no-load power demand (approximately 1-2 belt revolutions for belt conveyors and WO97/34130 PCT~S97/03477 bucket elevators, or the time it takes for the material to move from input to output for a horizontal screw).
3. Measured flow rate.
4. High horsepower alarm.
5. High horsepower alarm delay.
6. No-load-horsepower.
7. Number of zones.
Maximum system horsepower should be within the maximum horsepower rating of the electric motor. Maximum system horsepower is the absolute system full load condition, or maximum work that the combined electrical and ~ mechanical system can safely provide momentarily without going into electrical or mechanical overload. It is a result of the combined effect of the electrical requirements, the mechanical system together with the maximum amount of material that the mechanical system can ~ transport, convey, displace, etc, without overloading the motor.
The following description for the MSP will, for the sake of simplicity, take into consideration a fairly linear belt-conveying system requiring measurement in tons/hour. The power demand of the electric motor will be in horsepower. The conveyor belt speed is assumed to be fairly constant regardless of the amount of material being conveyed.
The displacing, processing, transporting, conveying system, etc, is initially allowed to run empty for a period of time until the power demand has stabilized.
WO97/34130 PCT~S97103477 Referring to Figure 5A, data from the power demand monitor 20 is fed to the MSP, which continually samples the instantaneous horsepower demand on the electric motor at step 42, taking lO samples and averaging the readings at steps 43 and 44. Ten samples are typically taken every 5 sec. All references to horsepower that follow mean average horsepower. A high horsepower value is entered into the MSP at 45. The averaged horsepower reading is continually compared to the high horsepower alarm setting at step 46. An alarm is triggered at 48 if the horsepower reading exceeds the high horsepower alarm ~ setting after a period of time determined by the high horsepower alarm delay at step 50. The alarm delay advantageously eliminates any false alarm caused by an isolated high horsepower value.
The monitored horsepower is verified by the system-no-load horsepower at step 52. The system-no-load horsepower is determined by the AUTO-CALIBRATE or AUTO-TARE
routines, which will be described below. If the monitored horsepower is below the system-no-load horsepower, an error message is sent to the terminal 26 at step 54 and an alarm is energized at 48. An alarm advantageously indicates that a fault has occurred in the conveying system. Because system-no-load horsepower is the minimum value needed to energize the system unloaded, horsepower values below that setting may indicate possible gear box malfunction;
slippage or disengagement of the motor form the conveyor; a disconnect switch left open by maintenance personnel; or WO97/34130 PCT~S97/03477 some possible problem involving the motor and its associated control system and power supply The AUT0-CALIBRATE routine is activated every time there is a new system installation or whenever the equation relating the horsepower to the flow rate has changed, such as would occur when changing the electric motor or any mechanical components of the displacement system, shrinking or stretching of the conveyor line, or - adding or modifying a system hardware.
Before calibrating the system through the AUTO-CALIBRATE routine, it is important that the mechanical integrity of the each component in the displacement system is in good operational condition. For example, lubricants are according to the gearbox or roller, etc. manufacturer's recommendations, and bearings and alignment are properly maintained to avoid excess friction, and general good ~ housekeeping is kept up to date. Any mechanical condition that would cause unusual or abnormal drag on the performance of the electric motor should be corrected before the calibration of the system.
The AUT0-CALIBRATE routine is activated through a push button 56 to signal to the MSP to proceed to monitor the horsepower for a preselected time while the displacement system runs empty of the displaceable material. For a belt conveyor system, it is preferable to run the system empty for l to 2 complete revolutions of the belt. For other systems not employing conveyors, the system should be run empty until it has stabilized (stabilization time). The AUTO-CALIBRATE routine will .
WO97/34130 PCT~S97/03477 identify the system-no-load horsepower after the elapsed pre-determined-time.
When the AUT0-CALIBRATE routine is enabled, a message is displayed at terminal 26 at step 58 to run the system empty. The system is then run for a pre-determined time at step 60. A timer is activated at step 62 for the predetermined period. The horsepower values are then sampled and summed at step 64 and averaged at step 66, which becomes the system-no-load value Y1 or B, as best shown in Figure 5B. Ten samples are typically taken for each 5 sec., and averaged. The average values are then further averaged at step 66. For a new system, the value determined at step 66 is also the no-load horsepower setting below which the MSP will cause an alarm output at 48.
The number of zones of the system is entered into the system at step 67. The MSP will then scan the number-of-zone parameter at step 68.
The next steps in the AUT0-CALIBRATE routine are to run the conveying system above system-no-load point, obtain a sample of the material being conveyed and weigh it, and calculate the flow rate from the size of the sample and the speed of the conveyor belt.
Referring to Figure 5C, for a single zone system, as disclosed in Figure 2, the conveying system is allowed to convey a sizable load beyond 50% of the difference between the maximum horsepower rating of the motor and the system-no-load horsepower, and then allowed to stabilize.
The 50% point between the system-no-load and the m~; mum WO97/34130 PCT~S97103477 --19-- .
horsepower is determined at steps 70 and 72. The maximum horsepower is entered at step 73 and this value is used to obtain the calibration point, which is a loading point at which a belt cut will be taken. A 50% region is defined in which the conveying system must be loaded preparatory to taking samples or belt cuts of the material being conveyed.
The larger the load on the system beyond the 50% point and the closer it is to the maximum load, the better the results would be in establishing the linear relationship of the horsepower to the flow rate.
The conveyor system is loaded at step 74 and the ~ horsepower output is monitored at step 76 to insure that the loading on the system is within the 50% region. The slope of the straight line will be determined by the MSP
only if the conveying system is loaded within the 50%
region. The 50~ region is the minimum horsepower necessary to establish the linearity of the graph for a single zone system.
The MSP will continue to monitor the horsepower while waiting to assume the proper loading constraints set by the number of zones in the system selected. When the horsepower loading on the system reaches the 50~ point or greater within the region, a message is displayed to the user at step 78 to stop the conveyor and take a belt cut, ~.
as best shown in Figure 5C.
A belt cut means stopping the conveying system and taking enough of a sample from the material on the belt to accurately determine the flow rate at that point in time. The sample must reasonable and representative of the WO97/34130 PCT~S97/0~77 entire belt. The longer the belt cut, the more accurate the computed material flow rate will be. An ideal sample would be to dump the entire contents of the conveyor into a container, weigh the material and divide the weight by the amount of time it took to dump the materials. The result will be an actual flow rate, such as tons/hour, of the conveyor system at a specific power demand of the electric motor, at a constant conveyor speed.
The horsepower at this point when the belt cut is taken is stored in the MSP at step 80 and the measured sample is entered at step 82 through the terminal 26. This ~ is called the measured flow rate.
Referring to Figure 5D, the MSP then calculates the slope of the line from the equation, M=(yz-yl)/(xz-x1)~
where Y2 = horsepower at the time the belt cut or sample was taken, Y1 = system-no-load horsepower, X2 = measured flow rate at Y2, and X1 = ~ by definition since system-no-load is defined as horsepower demand without processing material through it.
From the equation of the line, Y=M*X+B, the flow rate data X is calculated from the equation, X=(y-B)/M, where M=(y2-y1)/(x2-x1)~ Y1=B-The derivation of the mathematical model for the single zone system is shown at steps 83, 84, and 86.
WO97/34130 PCT~S97/03477 Switch 87 is pressed to confirm to the system that the measured flow rate X2 has been entered.
In a single zone system, the slope M is applicable for the entire range of the e~uation from system-no-load to maximum horsepower, where the system is fully loaded.
The AUTO-CALIBRATE routine is disabled at step 88 and the check on the horsepower relative to the system-no-load is enabled at step 90.
The MSP again enters the monitoring mode upon receiving the measured flow rate. For the single zone system, the monitoring mode is entered at step 92. The MSP
processes the horsepower information by the mathematical model established for the zone at step 94 and translates the horsepower information into flow rate data for the material over the entire horsepower range of the electrical motor. The MSP converts the flow rate data to a standard industrial analog output signal, such as 4-20 ma, 0-lO V, etc., to drive the various devices 28, 32 or 34 that provides material flow rate in units of weight per unit time.
The output is also converted to a pulse train and fed to the totalizer 36. The MSP integrates the material flow rate and converts it into pulses with a proportional time base, to drive totalizer, accumulators, counters, etc.
For example, l pulse/3,600 sec. may equal l ton/hour such that l,oO0 pulses/3,600 sec equals lO00 tons/hour.
WO97/34130 PCT~S97/03477 Referring to Figure 5B, the AUT0-CALIBRATE
routine will now be described with respect to a double-zone system.
A double-zone system is used to represent a semi-linear system, or a system that has a non-linear zone that can be approximated with reasonable accuracy by utilizing a straight line. The MSP calculates the points Y2 and Y3 to which the conveying system must be loaded preparatory to taking measured samples or belt cuts. These points are used to establish the slopes of the straight lines in zone A and zone B, as best shown in Figure 3. The first point ~ for taking the first belt cut is at, Y2 = B+0.25 (maximum horsepower - B).
The second point is, Y3 = B+ 0.75 (maximum horsepower - B).
The MSP calculates these two points at step 98.
~ A message to load the system greater than or equal to Y2 is sent to the terminal 26 at step 100. It is preferable that the loading occurs at slightly greater than Y2. Referring to Figure 5E, the horsepower is monitored at step 102 until the horsepower equals or exceeds Y2, at which point a message is sent to the terminal 26 at step 104 to stop the system and take a belt cut. This sample will represent X2 in the straight line graph in zone A, as best shown in Figure 3. The horsepower at Y2 is recorded at step 106.
The measured sample for X2 is entered into the MSP at 108 and the conveying system is restarted at step 110.
The system is then loaded until the horsepower reaches or exceeds Y3 at steps 112, 114 and 116, at which W O 97/34130 PCTrUS97/03477 point the conveying system is stopped and a belt cut is taken at step 118. Referring to Figure 5F, the horsepower at Y3 is recorded at step 120 and the measured flow rate at X3 is entered into the system at step 122. The mathematical model for the double-zone system is then calculated at steps 124 and 126.
For zone A, the slope Ma is calculated as follows, Ma = ( Y2 - Y1 ) /X2 ' where Y1 is the system-no-load horsepower, lo Y2 is the recorded horsepower at the time the belt cut for X2 is taken, and X2 is the actual measured flow rate from the belt cut.
The slope Mb for zone B is calculated as follows, Mb = (Y3 - Y2)/(X3 - X2)/
where, Y3 = the monitored horsepower for belt cut X3, Y2 = the monitored horsepower at belt cut X2, X3 = the measured flow rate from the belt cut at step 118, and X2 = the measured belt cut at step 104.
The mathematical model for the flow rate data in zone A is established at step 128 to be, X = (HP - B) /Ma/ for Yl<HP<Y2~ Y1=B-The mathematical model for zone B is established at step 130 to be, (HP Y2)/Mb + X2, for Y2<HP<HPMAX
Referring to Figure 5G, the AUTO-CALIBRATE
routine is disabled at step 132 and the check on the WO97134130 PCT~S97/03477 system-no-load horsepower is enabled at step 134. The MSP
now processes horsepower information by the mathematical models established for zones A and B and translates the horsepower information into flow rate data for the material being conveyed over the entire horsepower range of the electric motor, generally indicated at steps 136, 138, 140 and 142. The flow rate data is converted to an analog signal at step 144 or a pulse train at step 146, as desired.
The AUTO-CALIBRATE routine will now be described with reference to the three-zone system. Referring to ~ Figure 5H, the MSP calculates at step 146 three points, Y2, Y3 and Y4, at which to take actual samples from the material being conveyed, which will correspond to measured flow rates X2, X3, and X4. The three horsepower points are calculated as follows, Y2 = B+0.25(max HP-B), Y3 = B+0.50(max HP-B), and Y4 = B+0.75(max HP-B).
The conveying system is loaded to convey a sizable load until the first point, Y2 is reached, generally indicated at steps 148, 150 and 152. The conveying system is then stopped and a sample or belt cut is taken, which will correspond to the flow rate X2, generally indicated at step 154. The horsepower is recorded at step 156 and the measured flow rate is entered at 158.
Referring to Figure 5I, the displacement system is again loaded until the monitored horsepower reaches or exceeds Y3, generally indicated at steps 160, 162 and 164.
CA 02248923 l998-09-l4 W O 97/34130 PCTrUS97/03477 A second sample or belt cut is taken at step 166, which will correspond to flow rate X3. The monitored horsepower is recorded at step 168. The measured flow rate X3 is entered into the MSP at step 170.
Referring to Figure 5J, the conveying system is again loaded until the monitored horsepower reaches or exceeds Y4, as generally shown at steps 172, 174 and 176.
Actual measurement from the conveyor belt is then taken, which will correspond to flow rate X4, at step 178. The monitored horsepower is recorded at step 180 and the measured flow rate X4 is entered at 182.
The mathematical model for the three-zone system is then established by calculating the individual slope;
namely, Ma, Mb and Mc, generally indicated at steps 186, 188 and 190. The slopes are calculated from the following formulas, Ma = (Y2 - Y1)/X21 b ( 3 Y2)/(X3 - X2), and Mc (Y4 ~ Y3)/(X4 - X3)-The flow rate X is established at steps 192, 194 and 196 to be, X = (HP-B) /Mal for B<HP<Y2, X (HP Y2)/Mb + X2, for Y2<HP<Y3, and X = (HP-Y3)/MC + X3, for Y3<Hp<HpMAx.
Referring to Figure 5L, the MSP now processes horsepower information via the mathematical models established for each zone and translates the horsepower information into flow rate data for the material over the entire horsepower range of the electrical system.
W O 97/34130 PCTrUS97/03477 -26- .
The AUTO-CALIBRATE routine is disabled at step 197 and the horsepower check against the system-no-load settlng is enabled at step 199.
Depending on the value of the monitored horsepower, the appropriate model is used, generally indicated at steps 198, 201, 202 and 204. The output of the MSP is then converted to an analog signal at step 144 to provide flow rate data in units of weight per unit time.
A pulse train signal may also be provided at 146 to provide a totalizing output.
The MSP will constantly calculate and display the - flow rate through the above equations as it monitors the horsepower from the electric motor of the conveying system.
The AUTO-TARE routine will now be described with reference to Figures 5M, 5N, and 6A-6B. The AUTO-TARE
routine is used to recalibrate the system-no-load power - demand to take into account any increases or decreases in the mechanical drag of the conveying system, such as when the belt is wet or dry. For example, the AUTO-TARE routine should be performed after the conveyor belt has carried muddy or wet material for one belt revolution, after periodic grease and lubrication maintenance, after installing a new conveyor belt, etc. The AUTO-TARE routine ,hould also be performed at the start of each shift.
A switch 206 is energized and the AUTO-CALIBRATION routine is disabled in order to enable the AUTO-TARE routine at step 208. The conveying system is then run empty for a predetermined time at step 210. The motor horsepower is read periodically during this period W O97/34130 PCTrUS97/03477 and averaged at steps 220 and 224. The average value is then compared to the high horsepower alarm setting at step 226. If the value is below the high horsepower setting, it is then accepted as the new no-load or system-no-load horsepower at step 228. The new value is then used for the single, two and three zone models, at step 230.
~eferring to Figures 5N and 6A, for a single zone system, the new flow rate equation is calculated using the new system-no-load value BB at step 231.
For a two-zone system, the new flow rate equation is calculated at step 233. Referring to Figure 6B, the second zone equation is different depending on whether the new system-no-load horsepower is greater or lower than the original value.
Referring to Figures 5N and 6C, for a three-zone system, the new flow rate equation is calculated at step 235. The second and third zone equations are different depending on whether the new system-no-load horsepower is greater or lower than the original value.
For an n zone system, the equation for the n-th line segment is, Yn Mn(X Xn)+Yn+(YB Y1), where YB>Y1 (upshift), or Yn Mn(X Xn)+Yn~(Yl~YE~)I where YB<Y1 (dOWnShift)~
where Mn=(Yn+l~Yn)/(Xnl1 Xn)~ X1 0 The AUT0-TARE routine is available anytime the system is not performing an AUT0-CALIBRATE routine. The AUTo-TARE routine will raise, or lower the entire graph to a new location on the Y axis, as best shown in Figure 20.
The shift may have been caused by increase or decrease in W O 97/34130 PCTrUS97/03477 the mechanical deadload that did not affect the slope of the line equation. The AUTO-TARE routine is advantageously useful in calibrating the electrical system to any increase or decrease in mechanical drag prior to introducing material into the displacement system, offsetting or moving the entire equation to the proper system-no-load horsepower value prior to starting a production run.
Referring to Figure 7, a flow-chart is disclosed for a self-compensating integrator routine that automatically compensates or corrects the pulse output of the integrator at step 146 for the entire operating - spectrum of the flow rate monitor. Once the flow rate monitor has been calibrated, the self-compensating integrator routine continuously monitors the analog rate output and ensures that the number of pulses generated at step 146 is equal to output rate. For example, for a flow ~ rate of 100 tons/hr, the pulse output should be 100 pulses/hr, or 50 pulses/1800 sec, or 25 pulses/900 sec.
The analog output at step 146 is converted to a number of pulses equal to the flow rate X, divided by 60 min., generally indicated at step 232. The result of the division will produce a whole number, called the number of pulses #P, and a remainder .XX, whether .00 or some other number less than 1.00. The whole number #P is used as the target of comparison against the actual pulses AP from the output of the integrator at step 146 within a l min.
period. A one-minute timer is started at step 234 and the number of pulses generated at step 146 is accumulated for one minute at step 236. The timer is stopped at step 238 W O 97/34130 PCTrUS97/03477 and the number of pulses #P generated at step 232 is compared to the number AP accumulated at step 236, generally indicated at steps 240 and 242. In the meantime, the remainder .XX is accumulated at step 244 until the sum equal 1.00 or greatêr, generally indicated at step 246, at which tlme one pulse is directly added to the output pulses at step 248, to be placed between pulse time or during the period when no pulses are being generated (rest time). If the accumulated pulses AP are greater than the number of lo pulses #P generated at step 232, the rate of pulses at step 146 is slowed down. If the accumulated pulses AP are less - than the number of pulses #P generated at step 232, then the rate of pulses generated at step 146 is sped up. When the accumulated pulses equal the number of pulses generated from the analog signal, no correction is made.
The self-compensating integrator routine ~ advantageously eliminates the common practice of recalibrating the pulse output of the integrator circuitry when operating or shifting into a different range. Thus, regardless of the range, for example, from 0.09 tons/hr (3 lbs/min) to 980 tons/hr, the pulse output will accurately include the correct number of pulses per unit time based on the analog output.
Although the present invention is described with maximum three zones, a person of ordinary skill in the art will understand that any number of zones can be utilized, limited only by practicality and manpower constraints. A
three-zone model has been described above only for the sake of simplicity and to minimize the number of actual WO97/34130 - PCT~S97/03477 measurements that have to be taken to establish the slope of each line segment. A person of ordinary skill in the art will understand that greater accuracy will ~e attained with as more linear zones are utilized. Programming an n zone system would follow similar steps as disclosed with the three-zone system.
While this invention has been described as having preferred design, it is understood that it is capable of further modification, uses and/or adaptations of the invention following in general the principle of the invention and including such departures from the present - disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features set forth, and fall within the scope of the invention or the limits of the appended claims.
Maximum system horsepower should be within the maximum horsepower rating of the electric motor. Maximum system horsepower is the absolute system full load condition, or maximum work that the combined electrical and ~ mechanical system can safely provide momentarily without going into electrical or mechanical overload. It is a result of the combined effect of the electrical requirements, the mechanical system together with the maximum amount of material that the mechanical system can ~ transport, convey, displace, etc, without overloading the motor.
The following description for the MSP will, for the sake of simplicity, take into consideration a fairly linear belt-conveying system requiring measurement in tons/hour. The power demand of the electric motor will be in horsepower. The conveyor belt speed is assumed to be fairly constant regardless of the amount of material being conveyed.
The displacing, processing, transporting, conveying system, etc, is initially allowed to run empty for a period of time until the power demand has stabilized.
WO97/34130 PCT~S97103477 Referring to Figure 5A, data from the power demand monitor 20 is fed to the MSP, which continually samples the instantaneous horsepower demand on the electric motor at step 42, taking lO samples and averaging the readings at steps 43 and 44. Ten samples are typically taken every 5 sec. All references to horsepower that follow mean average horsepower. A high horsepower value is entered into the MSP at 45. The averaged horsepower reading is continually compared to the high horsepower alarm setting at step 46. An alarm is triggered at 48 if the horsepower reading exceeds the high horsepower alarm ~ setting after a period of time determined by the high horsepower alarm delay at step 50. The alarm delay advantageously eliminates any false alarm caused by an isolated high horsepower value.
The monitored horsepower is verified by the system-no-load horsepower at step 52. The system-no-load horsepower is determined by the AUTO-CALIBRATE or AUTO-TARE
routines, which will be described below. If the monitored horsepower is below the system-no-load horsepower, an error message is sent to the terminal 26 at step 54 and an alarm is energized at 48. An alarm advantageously indicates that a fault has occurred in the conveying system. Because system-no-load horsepower is the minimum value needed to energize the system unloaded, horsepower values below that setting may indicate possible gear box malfunction;
slippage or disengagement of the motor form the conveyor; a disconnect switch left open by maintenance personnel; or WO97/34130 PCT~S97/03477 some possible problem involving the motor and its associated control system and power supply The AUT0-CALIBRATE routine is activated every time there is a new system installation or whenever the equation relating the horsepower to the flow rate has changed, such as would occur when changing the electric motor or any mechanical components of the displacement system, shrinking or stretching of the conveyor line, or - adding or modifying a system hardware.
Before calibrating the system through the AUTO-CALIBRATE routine, it is important that the mechanical integrity of the each component in the displacement system is in good operational condition. For example, lubricants are according to the gearbox or roller, etc. manufacturer's recommendations, and bearings and alignment are properly maintained to avoid excess friction, and general good ~ housekeeping is kept up to date. Any mechanical condition that would cause unusual or abnormal drag on the performance of the electric motor should be corrected before the calibration of the system.
The AUT0-CALIBRATE routine is activated through a push button 56 to signal to the MSP to proceed to monitor the horsepower for a preselected time while the displacement system runs empty of the displaceable material. For a belt conveyor system, it is preferable to run the system empty for l to 2 complete revolutions of the belt. For other systems not employing conveyors, the system should be run empty until it has stabilized (stabilization time). The AUTO-CALIBRATE routine will .
WO97/34130 PCT~S97/03477 identify the system-no-load horsepower after the elapsed pre-determined-time.
When the AUT0-CALIBRATE routine is enabled, a message is displayed at terminal 26 at step 58 to run the system empty. The system is then run for a pre-determined time at step 60. A timer is activated at step 62 for the predetermined period. The horsepower values are then sampled and summed at step 64 and averaged at step 66, which becomes the system-no-load value Y1 or B, as best shown in Figure 5B. Ten samples are typically taken for each 5 sec., and averaged. The average values are then further averaged at step 66. For a new system, the value determined at step 66 is also the no-load horsepower setting below which the MSP will cause an alarm output at 48.
The number of zones of the system is entered into the system at step 67. The MSP will then scan the number-of-zone parameter at step 68.
The next steps in the AUT0-CALIBRATE routine are to run the conveying system above system-no-load point, obtain a sample of the material being conveyed and weigh it, and calculate the flow rate from the size of the sample and the speed of the conveyor belt.
Referring to Figure 5C, for a single zone system, as disclosed in Figure 2, the conveying system is allowed to convey a sizable load beyond 50% of the difference between the maximum horsepower rating of the motor and the system-no-load horsepower, and then allowed to stabilize.
The 50% point between the system-no-load and the m~; mum WO97/34130 PCT~S97103477 --19-- .
horsepower is determined at steps 70 and 72. The maximum horsepower is entered at step 73 and this value is used to obtain the calibration point, which is a loading point at which a belt cut will be taken. A 50% region is defined in which the conveying system must be loaded preparatory to taking samples or belt cuts of the material being conveyed.
The larger the load on the system beyond the 50% point and the closer it is to the maximum load, the better the results would be in establishing the linear relationship of the horsepower to the flow rate.
The conveyor system is loaded at step 74 and the ~ horsepower output is monitored at step 76 to insure that the loading on the system is within the 50% region. The slope of the straight line will be determined by the MSP
only if the conveying system is loaded within the 50%
region. The 50~ region is the minimum horsepower necessary to establish the linearity of the graph for a single zone system.
The MSP will continue to monitor the horsepower while waiting to assume the proper loading constraints set by the number of zones in the system selected. When the horsepower loading on the system reaches the 50~ point or greater within the region, a message is displayed to the user at step 78 to stop the conveyor and take a belt cut, ~.
as best shown in Figure 5C.
A belt cut means stopping the conveying system and taking enough of a sample from the material on the belt to accurately determine the flow rate at that point in time. The sample must reasonable and representative of the WO97/34130 PCT~S97/0~77 entire belt. The longer the belt cut, the more accurate the computed material flow rate will be. An ideal sample would be to dump the entire contents of the conveyor into a container, weigh the material and divide the weight by the amount of time it took to dump the materials. The result will be an actual flow rate, such as tons/hour, of the conveyor system at a specific power demand of the electric motor, at a constant conveyor speed.
The horsepower at this point when the belt cut is taken is stored in the MSP at step 80 and the measured sample is entered at step 82 through the terminal 26. This ~ is called the measured flow rate.
Referring to Figure 5D, the MSP then calculates the slope of the line from the equation, M=(yz-yl)/(xz-x1)~
where Y2 = horsepower at the time the belt cut or sample was taken, Y1 = system-no-load horsepower, X2 = measured flow rate at Y2, and X1 = ~ by definition since system-no-load is defined as horsepower demand without processing material through it.
From the equation of the line, Y=M*X+B, the flow rate data X is calculated from the equation, X=(y-B)/M, where M=(y2-y1)/(x2-x1)~ Y1=B-The derivation of the mathematical model for the single zone system is shown at steps 83, 84, and 86.
WO97/34130 PCT~S97/03477 Switch 87 is pressed to confirm to the system that the measured flow rate X2 has been entered.
In a single zone system, the slope M is applicable for the entire range of the e~uation from system-no-load to maximum horsepower, where the system is fully loaded.
The AUTO-CALIBRATE routine is disabled at step 88 and the check on the horsepower relative to the system-no-load is enabled at step 90.
The MSP again enters the monitoring mode upon receiving the measured flow rate. For the single zone system, the monitoring mode is entered at step 92. The MSP
processes the horsepower information by the mathematical model established for the zone at step 94 and translates the horsepower information into flow rate data for the material over the entire horsepower range of the electrical motor. The MSP converts the flow rate data to a standard industrial analog output signal, such as 4-20 ma, 0-lO V, etc., to drive the various devices 28, 32 or 34 that provides material flow rate in units of weight per unit time.
The output is also converted to a pulse train and fed to the totalizer 36. The MSP integrates the material flow rate and converts it into pulses with a proportional time base, to drive totalizer, accumulators, counters, etc.
For example, l pulse/3,600 sec. may equal l ton/hour such that l,oO0 pulses/3,600 sec equals lO00 tons/hour.
WO97/34130 PCT~S97/03477 Referring to Figure 5B, the AUT0-CALIBRATE
routine will now be described with respect to a double-zone system.
A double-zone system is used to represent a semi-linear system, or a system that has a non-linear zone that can be approximated with reasonable accuracy by utilizing a straight line. The MSP calculates the points Y2 and Y3 to which the conveying system must be loaded preparatory to taking measured samples or belt cuts. These points are used to establish the slopes of the straight lines in zone A and zone B, as best shown in Figure 3. The first point ~ for taking the first belt cut is at, Y2 = B+0.25 (maximum horsepower - B).
The second point is, Y3 = B+ 0.75 (maximum horsepower - B).
The MSP calculates these two points at step 98.
~ A message to load the system greater than or equal to Y2 is sent to the terminal 26 at step 100. It is preferable that the loading occurs at slightly greater than Y2. Referring to Figure 5E, the horsepower is monitored at step 102 until the horsepower equals or exceeds Y2, at which point a message is sent to the terminal 26 at step 104 to stop the system and take a belt cut. This sample will represent X2 in the straight line graph in zone A, as best shown in Figure 3. The horsepower at Y2 is recorded at step 106.
The measured sample for X2 is entered into the MSP at 108 and the conveying system is restarted at step 110.
The system is then loaded until the horsepower reaches or exceeds Y3 at steps 112, 114 and 116, at which W O 97/34130 PCTrUS97/03477 point the conveying system is stopped and a belt cut is taken at step 118. Referring to Figure 5F, the horsepower at Y3 is recorded at step 120 and the measured flow rate at X3 is entered into the system at step 122. The mathematical model for the double-zone system is then calculated at steps 124 and 126.
For zone A, the slope Ma is calculated as follows, Ma = ( Y2 - Y1 ) /X2 ' where Y1 is the system-no-load horsepower, lo Y2 is the recorded horsepower at the time the belt cut for X2 is taken, and X2 is the actual measured flow rate from the belt cut.
The slope Mb for zone B is calculated as follows, Mb = (Y3 - Y2)/(X3 - X2)/
where, Y3 = the monitored horsepower for belt cut X3, Y2 = the monitored horsepower at belt cut X2, X3 = the measured flow rate from the belt cut at step 118, and X2 = the measured belt cut at step 104.
The mathematical model for the flow rate data in zone A is established at step 128 to be, X = (HP - B) /Ma/ for Yl<HP<Y2~ Y1=B-The mathematical model for zone B is established at step 130 to be, (HP Y2)/Mb + X2, for Y2<HP<HPMAX
Referring to Figure 5G, the AUTO-CALIBRATE
routine is disabled at step 132 and the check on the WO97134130 PCT~S97/03477 system-no-load horsepower is enabled at step 134. The MSP
now processes horsepower information by the mathematical models established for zones A and B and translates the horsepower information into flow rate data for the material being conveyed over the entire horsepower range of the electric motor, generally indicated at steps 136, 138, 140 and 142. The flow rate data is converted to an analog signal at step 144 or a pulse train at step 146, as desired.
The AUTO-CALIBRATE routine will now be described with reference to the three-zone system. Referring to ~ Figure 5H, the MSP calculates at step 146 three points, Y2, Y3 and Y4, at which to take actual samples from the material being conveyed, which will correspond to measured flow rates X2, X3, and X4. The three horsepower points are calculated as follows, Y2 = B+0.25(max HP-B), Y3 = B+0.50(max HP-B), and Y4 = B+0.75(max HP-B).
The conveying system is loaded to convey a sizable load until the first point, Y2 is reached, generally indicated at steps 148, 150 and 152. The conveying system is then stopped and a sample or belt cut is taken, which will correspond to the flow rate X2, generally indicated at step 154. The horsepower is recorded at step 156 and the measured flow rate is entered at 158.
Referring to Figure 5I, the displacement system is again loaded until the monitored horsepower reaches or exceeds Y3, generally indicated at steps 160, 162 and 164.
CA 02248923 l998-09-l4 W O 97/34130 PCTrUS97/03477 A second sample or belt cut is taken at step 166, which will correspond to flow rate X3. The monitored horsepower is recorded at step 168. The measured flow rate X3 is entered into the MSP at step 170.
Referring to Figure 5J, the conveying system is again loaded until the monitored horsepower reaches or exceeds Y4, as generally shown at steps 172, 174 and 176.
Actual measurement from the conveyor belt is then taken, which will correspond to flow rate X4, at step 178. The monitored horsepower is recorded at step 180 and the measured flow rate X4 is entered at 182.
The mathematical model for the three-zone system is then established by calculating the individual slope;
namely, Ma, Mb and Mc, generally indicated at steps 186, 188 and 190. The slopes are calculated from the following formulas, Ma = (Y2 - Y1)/X21 b ( 3 Y2)/(X3 - X2), and Mc (Y4 ~ Y3)/(X4 - X3)-The flow rate X is established at steps 192, 194 and 196 to be, X = (HP-B) /Mal for B<HP<Y2, X (HP Y2)/Mb + X2, for Y2<HP<Y3, and X = (HP-Y3)/MC + X3, for Y3<Hp<HpMAx.
Referring to Figure 5L, the MSP now processes horsepower information via the mathematical models established for each zone and translates the horsepower information into flow rate data for the material over the entire horsepower range of the electrical system.
W O 97/34130 PCTrUS97/03477 -26- .
The AUTO-CALIBRATE routine is disabled at step 197 and the horsepower check against the system-no-load settlng is enabled at step 199.
Depending on the value of the monitored horsepower, the appropriate model is used, generally indicated at steps 198, 201, 202 and 204. The output of the MSP is then converted to an analog signal at step 144 to provide flow rate data in units of weight per unit time.
A pulse train signal may also be provided at 146 to provide a totalizing output.
The MSP will constantly calculate and display the - flow rate through the above equations as it monitors the horsepower from the electric motor of the conveying system.
The AUTO-TARE routine will now be described with reference to Figures 5M, 5N, and 6A-6B. The AUTO-TARE
routine is used to recalibrate the system-no-load power - demand to take into account any increases or decreases in the mechanical drag of the conveying system, such as when the belt is wet or dry. For example, the AUTO-TARE routine should be performed after the conveyor belt has carried muddy or wet material for one belt revolution, after periodic grease and lubrication maintenance, after installing a new conveyor belt, etc. The AUTO-TARE routine ,hould also be performed at the start of each shift.
A switch 206 is energized and the AUTO-CALIBRATION routine is disabled in order to enable the AUTO-TARE routine at step 208. The conveying system is then run empty for a predetermined time at step 210. The motor horsepower is read periodically during this period W O97/34130 PCTrUS97/03477 and averaged at steps 220 and 224. The average value is then compared to the high horsepower alarm setting at step 226. If the value is below the high horsepower setting, it is then accepted as the new no-load or system-no-load horsepower at step 228. The new value is then used for the single, two and three zone models, at step 230.
~eferring to Figures 5N and 6A, for a single zone system, the new flow rate equation is calculated using the new system-no-load value BB at step 231.
For a two-zone system, the new flow rate equation is calculated at step 233. Referring to Figure 6B, the second zone equation is different depending on whether the new system-no-load horsepower is greater or lower than the original value.
Referring to Figures 5N and 6C, for a three-zone system, the new flow rate equation is calculated at step 235. The second and third zone equations are different depending on whether the new system-no-load horsepower is greater or lower than the original value.
For an n zone system, the equation for the n-th line segment is, Yn Mn(X Xn)+Yn+(YB Y1), where YB>Y1 (upshift), or Yn Mn(X Xn)+Yn~(Yl~YE~)I where YB<Y1 (dOWnShift)~
where Mn=(Yn+l~Yn)/(Xnl1 Xn)~ X1 0 The AUT0-TARE routine is available anytime the system is not performing an AUT0-CALIBRATE routine. The AUTo-TARE routine will raise, or lower the entire graph to a new location on the Y axis, as best shown in Figure 20.
The shift may have been caused by increase or decrease in W O 97/34130 PCTrUS97/03477 the mechanical deadload that did not affect the slope of the line equation. The AUTO-TARE routine is advantageously useful in calibrating the electrical system to any increase or decrease in mechanical drag prior to introducing material into the displacement system, offsetting or moving the entire equation to the proper system-no-load horsepower value prior to starting a production run.
Referring to Figure 7, a flow-chart is disclosed for a self-compensating integrator routine that automatically compensates or corrects the pulse output of the integrator at step 146 for the entire operating - spectrum of the flow rate monitor. Once the flow rate monitor has been calibrated, the self-compensating integrator routine continuously monitors the analog rate output and ensures that the number of pulses generated at step 146 is equal to output rate. For example, for a flow ~ rate of 100 tons/hr, the pulse output should be 100 pulses/hr, or 50 pulses/1800 sec, or 25 pulses/900 sec.
The analog output at step 146 is converted to a number of pulses equal to the flow rate X, divided by 60 min., generally indicated at step 232. The result of the division will produce a whole number, called the number of pulses #P, and a remainder .XX, whether .00 or some other number less than 1.00. The whole number #P is used as the target of comparison against the actual pulses AP from the output of the integrator at step 146 within a l min.
period. A one-minute timer is started at step 234 and the number of pulses generated at step 146 is accumulated for one minute at step 236. The timer is stopped at step 238 W O 97/34130 PCTrUS97/03477 and the number of pulses #P generated at step 232 is compared to the number AP accumulated at step 236, generally indicated at steps 240 and 242. In the meantime, the remainder .XX is accumulated at step 244 until the sum equal 1.00 or greatêr, generally indicated at step 246, at which tlme one pulse is directly added to the output pulses at step 248, to be placed between pulse time or during the period when no pulses are being generated (rest time). If the accumulated pulses AP are greater than the number of lo pulses #P generated at step 232, the rate of pulses at step 146 is slowed down. If the accumulated pulses AP are less - than the number of pulses #P generated at step 232, then the rate of pulses generated at step 146 is sped up. When the accumulated pulses equal the number of pulses generated from the analog signal, no correction is made.
The self-compensating integrator routine ~ advantageously eliminates the common practice of recalibrating the pulse output of the integrator circuitry when operating or shifting into a different range. Thus, regardless of the range, for example, from 0.09 tons/hr (3 lbs/min) to 980 tons/hr, the pulse output will accurately include the correct number of pulses per unit time based on the analog output.
Although the present invention is described with maximum three zones, a person of ordinary skill in the art will understand that any number of zones can be utilized, limited only by practicality and manpower constraints. A
three-zone model has been described above only for the sake of simplicity and to minimize the number of actual WO97/34130 - PCT~S97/03477 measurements that have to be taken to establish the slope of each line segment. A person of ordinary skill in the art will understand that greater accuracy will ~e attained with as more linear zones are utilized. Programming an n zone system would follow similar steps as disclosed with the three-zone system.
While this invention has been described as having preferred design, it is understood that it is capable of further modification, uses and/or adaptations of the invention following in general the principle of the invention and including such departures from the present - disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features set forth, and fall within the scope of the invention or the limits of the appended claims.
Claims (25)
1. A flow rate monitor for indicating the amount of material being displaced in a displacement system having an electric motor as a prime mover, comprising:
a) power demand monitor for being operably connected to the electric motor;
b) a programmable controller operably connected to said power demand monitor, said controller being adapted to convert the data from said power demand monitor and convert it to flow rate data using a linear relationship between the power demand of the electric motor and the flow rate of the material; and c) indicator for indicating the flow rate of the material.
a) power demand monitor for being operably connected to the electric motor;
b) a programmable controller operably connected to said power demand monitor, said controller being adapted to convert the data from said power demand monitor and convert it to flow rate data using a linear relationship between the power demand of the electric motor and the flow rate of the material; and c) indicator for indicating the flow rate of the material.
2. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller is a programmable logic controller.
a) said programmable controller is a programmable logic controller.
3. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller includes an analog output for being connected to a display.
a) said programmable controller includes an analog output for being connected to a display.
4. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller includes a pulse train output for being connected to a totalizer display.
a) said programmable controller includes a pulse train output for being connected to a totalizer display.
5. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller includes an analog output for being connected to a display;
b) said programmable controller includes a pulse train output for being connected to a totalizer display; and c) said pulse train output is automatically calibrated with respect to said analog output such that the number of pulses per unit time is equal the flow rate over the same unit of time.
a) said programmable controller includes an analog output for being connected to a display;
b) said programmable controller includes a pulse train output for being connected to a totalizer display; and c) said pulse train output is automatically calibrated with respect to said analog output such that the number of pulses per unit time is equal the flow rate over the same unit of time.
6. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller is adapted to generate an output when a preselected high value is exceeded by the power demand of the prime mover, said output for being connected to an alarm device.
a) said programmable controller is adapted to generate an output when a preselected high value is exceeded by the power demand of the prime mover, said output for being connected to an alarm device.
7. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller is adapted to generate an output when the power demand of the electric motor falls below a low value, said output for being connected to an alarm device.
a) said programmable controller is adapted to generate an output when the power demand of the electric motor falls below a low value, said output for being connected to an alarm device.
8. A flow rate monitor as in Claim 1, wherein:
a) said programmable controller is adapted to be calibrated to an to existing displacement system.
a) said programmable controller is adapted to be calibrated to an to existing displacement system.
9. A flow rate monitor for indicating the amount of material being displaced in a displacement system having a prime mover, comprising:
a) power demand monitor operably connected to the prime mover and adapted to provide power demand data of the prime mover;
b) a programmable controller operably connected to said power demand monitor, said controller being adapted to convert data from said power demand monitor to flow rate data using the following equations, X=(HP-B)/M, B~HP~HP MAX, and M=(Y2-B)/X2 where, X is the flow rate of the material being conveyed, in units of weight per unit of time, where, HP is the monitored power demand of the prime mover, B is the system-no-load power demand with the displacement system running empty, and M is the slope of the straight line, Y2 is a power demand greater than B, and X2 is an actual flow rate measurement taken at Y2; and c) said programmable controller including an output signal representing the flow rate of the material being conveyed based on said equations, said output signal for being connected to an output device.
a) power demand monitor operably connected to the prime mover and adapted to provide power demand data of the prime mover;
b) a programmable controller operably connected to said power demand monitor, said controller being adapted to convert data from said power demand monitor to flow rate data using the following equations, X=(HP-B)/M, B~HP~HP MAX, and M=(Y2-B)/X2 where, X is the flow rate of the material being conveyed, in units of weight per unit of time, where, HP is the monitored power demand of the prime mover, B is the system-no-load power demand with the displacement system running empty, and M is the slope of the straight line, Y2 is a power demand greater than B, and X2 is an actual flow rate measurement taken at Y2; and c) said programmable controller including an output signal representing the flow rate of the material being conveyed based on said equations, said output signal for being connected to an output device.
10. A flow rate monitor for indicating the amount of material being displaced in a displacement system having a prime mover, comprising:
a) power demand monitor operably connected to the prime mover and adapted to provide power demand data of the prime mover;
b) a programmable controller operably connected to said power demand monitor, said controller being adapted to convert data from said power demand monitor to flow rate data using at least two linear equations as follows, X=(HP-B)/M a, B~HP~Y2 M a=(Y2-B)/X2 X=(HP-Y2)/M b + X2, Y2~HP~HP MAX
M b= (Y3-Y2) / (X3 X2) where, X is the flow rate of the material being conveyed, in units of weight per unit of time, where, HP is the monitored power demand of the prime mover, B is the system-no-load power demand with the displacement system running empty, M a is the slope of a first line segment, M b is the slop of a second line segment, line, Y2 is the power demand at 25% of the difference between the maximum power demand of the prime mover and the system-no-load power demand, X2 is an actual flow rate measurement taken at Y2, X3 is an actual flow rate measurement taken at Y3, Y3 is the power demand at 75% of the difference between the maximum power demand of the prime mover and the system-no-load power demand; and c) said programmable controller including an output signal representing the flow rate of the material being conveyed based on said equations, said output signal for being connected to an output device.
a) power demand monitor operably connected to the prime mover and adapted to provide power demand data of the prime mover;
b) a programmable controller operably connected to said power demand monitor, said controller being adapted to convert data from said power demand monitor to flow rate data using at least two linear equations as follows, X=(HP-B)/M a, B~HP~Y2 M a=(Y2-B)/X2 X=(HP-Y2)/M b + X2, Y2~HP~HP MAX
M b= (Y3-Y2) / (X3 X2) where, X is the flow rate of the material being conveyed, in units of weight per unit of time, where, HP is the monitored power demand of the prime mover, B is the system-no-load power demand with the displacement system running empty, M a is the slope of a first line segment, M b is the slop of a second line segment, line, Y2 is the power demand at 25% of the difference between the maximum power demand of the prime mover and the system-no-load power demand, X2 is an actual flow rate measurement taken at Y2, X3 is an actual flow rate measurement taken at Y3, Y3 is the power demand at 75% of the difference between the maximum power demand of the prime mover and the system-no-load power demand; and c) said programmable controller including an output signal representing the flow rate of the material being conveyed based on said equations, said output signal for being connected to an output device.
11. A method for measuring the amount of material being displaced in a displacement system with a prime mover, in a substantially liner region of operation of the prime mover where the power demand of the prime mover is linearly related to the flow rate of the material, comprising the steps of:
a) calibrating the system to establish the linear relationship of the power demand to the flow rate;
b) measuring the power demand of the prime mover; and c) calculating and displaying the flow rate of the material being conveyed from the linear relationship.
a) calibrating the system to establish the linear relationship of the power demand to the flow rate;
b) measuring the power demand of the prime mover; and c) calculating and displaying the flow rate of the material being conveyed from the linear relationship.
12. A method as in Claim 11, wherein said calibrating step comprises the steps of:
a) measuring the power demand of the prime mover when the displacement system is empty, thereby obtaining the system-no-load power demand;
b) measuring the power demand of the prime mover at a point between 50% of the maximum power output of the prime mover and 50% of the system-no-load power demand;
c) taking a sample of the material being displaced at the point and calculating the actual flow rate of the material; and d) generating a straight line relationship between the power demand of the prime mover and the rate of flow of the material using the data obtained from steps a, b and c.
a) measuring the power demand of the prime mover when the displacement system is empty, thereby obtaining the system-no-load power demand;
b) measuring the power demand of the prime mover at a point between 50% of the maximum power output of the prime mover and 50% of the system-no-load power demand;
c) taking a sample of the material being displaced at the point and calculating the actual flow rate of the material; and d) generating a straight line relationship between the power demand of the prime mover and the rate of flow of the material using the data obtained from steps a, b and c.
13. A method as in Claim 11, and further comprising the step of:
a) activating an alarm when the power demand exceeds a predetermined high value.
a) activating an alarm when the power demand exceeds a predetermined high value.
14. A method as in Claim 11, and further comprising the step of:
a) activating an alarm when the power demand drops below a predetermined low value.
a) activating an alarm when the power demand drops below a predetermined low value.
15. A method as in Claim 11, and further comprising the steps of:
a) taking several samples of the power demand; and b) averaging the samples prior to calculating the flow rate.
a) taking several samples of the power demand; and b) averaging the samples prior to calculating the flow rate.
16. A method as in Claim 11, and further comprising the steps of:
a) recalibrating the system-no-load power demand periodically; and b) recalculating the linear relationship.
a) recalibrating the system-no-load power demand periodically; and b) recalculating the linear relationship.
17. A method as in Claim 11, and further comprising the steps of:
a) converting the flow rate data into an analog signal adapted to drive an indicating device.
a) converting the flow rate data into an analog signal adapted to drive an indicating device.
18. A method as in Claim 17, and further comprising the step of:
a) converting the flow rate data into a pulse train output adapted to drive an integrator.
a) converting the flow rate data into a pulse train output adapted to drive an integrator.
19. A method as in Claim 18, and further comprising the steps of:
a) monitoring the analog flow rate data and the pulse train output; and b) automatically recalibrating the pulse train output such that the number of pulses per unit time is equal to the analog flow rate data over the same unit of time.
a) monitoring the analog flow rate data and the pulse train output; and b) automatically recalibrating the pulse train output such that the number of pulses per unit time is equal to the analog flow rate data over the same unit of time.
20. A method for measuring the amount of material being displaced in a displacement system with a prime mover, comprising the steps of:
a) partitioning the region of operation of the prime mover into at least first and second linear regions where the power demand in each region is substantially linearly related to the flow rate of the material;
b) calibrating the system to establish the linear relationship of the power demand to the flow rate in each region;
c) measuring the power demand of the prime mover;
d) determining the region of operation of the prime mover; and e) calculating and displaying the flow rate of the material being displaced from the linear relationship of the respective region.
a) partitioning the region of operation of the prime mover into at least first and second linear regions where the power demand in each region is substantially linearly related to the flow rate of the material;
b) calibrating the system to establish the linear relationship of the power demand to the flow rate in each region;
c) measuring the power demand of the prime mover;
d) determining the region of operation of the prime mover; and e) calculating and displaying the flow rate of the material being displaced from the linear relationship of the respective region.
21. A method as in Claim 20, wherein said calibrating step comprises the steps of:
a) measuring the power demand of the prime mover when the displacement system is empty, thereby obtaining the system-no-load power demand;
b) measuring the power demand of the prime mover at 25% of the difference between the maximum power output of the prime mover and the system-no-load power demand;
c) taking a sample of the material being displaced at the 25% point and calculating the actual flow rate of the material;
d) measuring the power demand of the prime mover at 75% of the difference between the maximum power output of the prime mover and the system-no-load power demand;
e) taking a sample of the material being displaced at the 75% point and calculating the actual flow rate of the material; and f) generating a straight line relationship between the power demand of the prime mover and the rate of flow of the material for each region using the data obtained from steps a, b, c, d and e.
a) measuring the power demand of the prime mover when the displacement system is empty, thereby obtaining the system-no-load power demand;
b) measuring the power demand of the prime mover at 25% of the difference between the maximum power output of the prime mover and the system-no-load power demand;
c) taking a sample of the material being displaced at the 25% point and calculating the actual flow rate of the material;
d) measuring the power demand of the prime mover at 75% of the difference between the maximum power output of the prime mover and the system-no-load power demand;
e) taking a sample of the material being displaced at the 75% point and calculating the actual flow rate of the material; and f) generating a straight line relationship between the power demand of the prime mover and the rate of flow of the material for each region using the data obtained from steps a, b, c, d and e.
22. A method as in Claim 20, and further comprising the step of:
a) activating an alarm when the power demand exceeds a predetermined high value.
a) activating an alarm when the power demand exceeds a predetermined high value.
23. A method as in Claim 20, and further comprising the step of:
a) activating an alarm when the power demand drops below a predetermined low value.
a) activating an alarm when the power demand drops below a predetermined low value.
24. A method as in Claim 20, wherein:
a) taking several samples of the power demand; and b) averaging the samples prior to calculating the flow rate.
a) taking several samples of the power demand; and b) averaging the samples prior to calculating the flow rate.
25. A method as in Claim 20, and further comprising the steps of:
a) recalibrating the system-no-load power demand periodically; and b) recalculating the linear relationship of each region.
a) recalibrating the system-no-load power demand periodically; and b) recalculating the linear relationship of each region.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1317596P | 1996-03-12 | 1996-03-12 | |
| US60/013,175 | 1996-03-12 | ||
| US1661296P | 1996-05-01 | 1996-05-01 | |
| US60/016,612 | 1996-05-01 | ||
| US69336096A | 1996-08-06 | 1996-08-06 | |
| US08/693,360 | 1996-08-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2248923A1 true CA2248923A1 (en) | 1997-09-18 |
Family
ID=27359797
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002248923A Abandoned CA2248923A1 (en) | 1996-03-12 | 1997-03-12 | Rate monitor for a displacement system utilizing the power demand of the prime mover of the system to provide the flow rate data of the material being displaced |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US6317656B1 (en) |
| AU (1) | AU2197197A (en) |
| CA (1) | CA2248923A1 (en) |
| WO (1) | WO1997034130A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2192955B1 (en) * | 2001-09-28 | 2004-09-16 | Jose Antonio Garcia Mesa | HEAVY SYSTEM OF MOVING PRODUCTS. |
| US7193162B2 (en) * | 2004-03-12 | 2007-03-20 | Glowe Consulting Services Inc. | Method for assessing the operation of a conveying apparatus |
| US7550681B2 (en) * | 2007-05-25 | 2009-06-23 | Chung Yuan Christian University | Method and apparatus for measuring weight of CNC workpieces |
| GB2489703A (en) * | 2011-04-04 | 2012-10-10 | Blue Fountain Systems Ltd | System for monitoring quantity of feed delivered from a silo |
| US9920878B2 (en) * | 2012-04-20 | 2018-03-20 | Lincoln Industrial Corporation | Lubrication system and controller |
| US20140041949A1 (en) * | 2012-08-09 | 2014-02-13 | Melvin D KERNUTT | Indirect Material Weighing Sensor |
| DE202013001935U1 (en) * | 2013-03-01 | 2014-06-03 | Big Dutchman International Gmbh | Conveying device for conveying animal products in a farm |
| EA028198B1 (en) | 2012-10-24 | 2017-10-31 | Биг Дачман Интернэшнл Гмбх | Conveyor and method for conveying animal waste products in an agricultural facility |
| US9598269B2 (en) * | 2014-04-04 | 2017-03-21 | David R. Hall | Motorized lifting device with a grooved drum for lifting a load and determining a weight of the load while lifting |
| US9567195B2 (en) * | 2013-05-13 | 2017-02-14 | Hall David R | Load distribution management for groups of motorized lifting devices |
| DE202014007282U1 (en) | 2014-09-12 | 2015-12-16 | Big Dutchman International Gmbh | metering |
| DE202016105370U1 (en) | 2016-09-27 | 2018-01-02 | Big Dutchman International Gmbh | Feeding device for poultry |
| EP3936836A1 (en) * | 2020-07-07 | 2022-01-12 | Tecno S.r.l. | Method and measurement kit for weighing conveyor belts |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2681763A (en) | 1950-11-20 | 1954-06-22 | Conveyor Company Inc | Integrating system for conveyer scales |
| US3722660A (en) | 1971-11-26 | 1973-03-27 | Snead E Des | Weighing apparatus |
| US3899915A (en) * | 1973-11-07 | 1975-08-19 | Reliance Electric Co | Conveyor scale calibration |
| US3960225A (en) * | 1973-11-21 | 1976-06-01 | Hyer Industries, Inc. | Conveyor belt system with positional transformation of weight data |
| US3979055A (en) * | 1974-05-03 | 1976-09-07 | A.O. Smith Harvestore, Inc. | Weighing system for conveying means |
| US3942625A (en) * | 1974-09-13 | 1976-03-09 | Snead Edwin Des | Portable conveyor load measuring apparatus |
| US3985266A (en) * | 1975-08-13 | 1976-10-12 | K-Tron Corporation | Apparatus for controlling the feed rate and batch size of a material feeder |
| US4101831A (en) * | 1976-04-12 | 1978-07-18 | Rexnord Inc. | Load monitoring apparatus and method |
| US4199871A (en) * | 1978-02-23 | 1980-04-29 | Ward Systems, Inc. | Automatic hold speed setting control method and apparatus used with a continuous automatic wood veneer dryer conveyor speed control monitoring computer apparatus |
| US4954975A (en) | 1988-08-10 | 1990-09-04 | K-Tron International, Inc. | Weigh feeding system with self-tuning stochastic control and weight and actuator measurements |
| US4863009A (en) | 1988-11-14 | 1989-09-05 | Alberta Energy Company Ltd. | Control system for an endless belt conveyor train |
| GB9024731D0 (en) | 1990-11-14 | 1991-01-02 | Giles Alan F | Particle weighing apparatus and method |
| US5393939A (en) * | 1992-11-20 | 1995-02-28 | Westinghouse Electric Corp. | Apparatus and method for weighing moving objects |
| US5318409A (en) * | 1993-03-23 | 1994-06-07 | Westinghouse Electric Corp. | Rod pump flow rate determination from motor power |
-
1997
- 1997-03-12 CA CA002248923A patent/CA2248923A1/en not_active Abandoned
- 1997-03-12 WO PCT/US1997/003477 patent/WO1997034130A1/en active Application Filing
- 1997-03-12 AU AU21971/97A patent/AU2197197A/en not_active Abandoned
-
1998
- 1998-03-13 US US09/041,693 patent/US6317656B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US6317656B1 (en) | 2001-11-13 |
| AU2197197A (en) | 1997-10-01 |
| WO1997034130A1 (en) | 1997-09-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |