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Publication numberUS3928848 A
Publication typeGrant
Publication dateDec 23, 1975
Filing dateMay 28, 1974
Priority dateMay 28, 1974
Publication numberUS 3928848 A, US 3928848A, US-A-3928848, US3928848 A, US3928848A
InventorsJules Eugene Banville
Original AssigneeJules Eugene Banville
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Supervisory control system
US 3928848 A
Abstract
A supervisory control and self-powered indicating system is provided for controlling the operation of a remote electrically operated device from a control station and for indicating at the control station either the operability of the remote device or the absence of an alarm condition, in which a pair of face-to-face diodes are connected in series across the transmission lines at the remote location, with the mid-point between the diodes connected through a third diode and through a condition responsive switch to earth ground. The return connection through earth ground at the control station is made through a relay coil and back-to-back diodes connected in series across the transmission lines at the control station. Telemetry is provided through the opening and closing of the condition responsive switch, with the time that this switch remains in a given condition being monitored by the length of time the switch associated with the relay coil at the control station remains in this given condition. Alternatively, the condition responsive switch changes state in response to a predetermined alarm condition which is indicated by a change of state of the switch associated with the relay at the control station.
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United States Patent Banville Dec. 23, 1975 SUPERVISORY CONTROL SYSTEM [57] ABSTRACT [76] I v t J l Eugene B ill 161 H s A supervisory control and self-powered indicating sys- Cumberland, RI, 02908 tem is provided for controlling the operation of a remote electrically operated device from a control sta- [22] Flled' May 1974 tion and for indicating at the control station either the [21] Appl. NQ; 473,358 operability of the remote device or the absence of an alarm condition, in which a pair of face-to-face diodes are connected in series across the transmission lines at ESCCII; 340/409; 340/310 R the remote location with the mid point between the F. of e a e i; r I u e 1 e e I I s e v I e e e s U a a le 0 Same 340/409 310 319 condition responsive switch to earth ground. The re- 0/255 177 239 turn connection through earth ground at the control I station is made through a relay coil and back-to-back [56] References cued diodes connected in series across the transmission UNITED STATES PATENTS lines at the control station. Telemetry is provided 3,448,447 6/1969 Tetherow 340/409 R hr gh he opening and closing of the condition re- 3,566,398 2/1971 Rowell 340/409 R sponsive switch, with the time that this switch remains 3,588,891 6/1971 Porter 340/409 R in a given condition being monitored by the length of 3,604,262 9/1971 Craddock 340/239 R time the Switch associated with the relay i at the g control station remains in this given condition. Alter- 337423m 6,1973 wifiiiw iiii:.......::::::1::133: 340/239 R naively, the condition Switch changes State Primary Examiner-Harold 1. Pitts Attorney, Agent, or Firm--William Frederick Werner in response to a-predetermined alarm condition which is indicated by a'change of state of the switch associated with the relay at the control station.

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SUPERVISORY CONTROL SYSTEM BACKGROUND OF THE INVENTION This invention relates to apparatus for the supervisory control of a remote device and more particularly to provision of a self-powered indicating system utilizing the transmission lines between the remote and con trol stations, as a source of power for the indicating system, whereby control of a remote device and indication of its operation are indicated by signals transmitted back to the control station via earth ground and pairs of diodes across the transmission lines at the remote and control stations.

In the operation of, for instance, remote valving circuits there is a necessity for monitoring not only the state of the valve, but also to insure that no unauthorized entry has been made at the remote station. This is particularly true of a remote pumping station in which intruders may often either damage or inactivate the equipment unbeknownst to the personnel at the control station. Additionally, there is a need not only for an alarm system but also for a system which indicates the operability of the equipment at the remote station.

As described in US. Pat. No. 2,932,014, issued to J. C. Thoresen on Apr. 15, 1960, a supervisory system is illustrated in which a separate power supply at the remote location provides electrical current across a potentiometer, the wiper arm of which is mechanically connected to a valve such that the potential applied to the center of a choke coil across the power lines is proportional to the valve position. It is thus the magnitude of the potential delivered to the center of this choke coil when delivered back to the control station which provides for the indication of the state of the remote valve. It will be appreciated that depending on the distances between the control and remote stations this type of indicating system relys heavily on the stability of the remote power supply and the absence of change of any transmission line condition.

The problems of this type of indicating system are solved by the subject invention whose remote circuit derives its power directly from the transmission lines to the remote location and which in general provides an indication of the state of the remote device or the security of the remote station via the complete interruption or non-interruption of an earth ground connection at the remote location to the operative part of the remote indicating circuit.

This binary on/off operation of the subject circuit permits a binary on/off operation of the indicating or alarm circuit at the control station and thus is not amplitude sensitive, or sensitive to changes in the characteristics of the transmission lines between the control and remote stations.

Power for the remote station transmitting device is derived from two face-to-face diodes connected in series across the transmission lines inter-connecting the control and remote stations. The voltage at the midpoint of these diodes is applied through a further diode and an condition responsive switch to earth ground at the remote location. At the control station aback-toback pair of diodes is connected in series through re spective resistors across the same transmission line. The mid-point of these back-to-back diodes is connected through a relay coil to earth ground such that when the condition responsive switch at the remote location is closed, the relay coil at the control station is energized. In one embodiment, an alarm condition is indicated by an earth ground interruption at the remote location. This can be due to unauthorized access through a door or window at the remote station. Alternatively, any sensed condition at the remote station can be translated into the amount of time that the earth ground is connected to the remote circuit via the condition responsive switch. This switch closing time can be monitored at the control station and correlated with the sensed condition. Thus, for example, fluid flow at the remote station can be translated into how much time in a giventime interval, the earth ground is connected and this time can be monitored at the control station. Moreover, a Powder-On indicator can be provided at the control station and in a further embodimom, a voltage compensation circuit is provided.

SUMMARY OF THE INVENTION A self-powered supervisory control and indicating circuit is thus provided for indicating one ofa variety of conditions at a remote location.

It is therefore an object of this invention to provide self-powered supervisory control and condition indicating apparatus at a remote location and control station in which earth ground is used as one of the conducting paths.

It is a further object of this invention to provide a supervisory and control circuit used with remote elec' trical apparatus 'in which both the operation of the apparatus is indicated at a control station as well as the absence of an intruder or any alarm condition.

Other features and advantages of the invention will appear from the ensuing description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating one embodiment of the present invention; and

FIG. 2 is a schematic diagram illustrating a second embodiment of the subject invention, indicating the use of the subject circuit for telemetry purposes.

DETAILED DESCRIPTION Referring to FIG. 1, a control station 10 is shown connected to a remote station 11 via transmission lines 12 and 13. In one embodiment, remote station 11 may be a pump house remote from the control station 10 and includes a pump 14 or any other electronic or electromechanical device.

In order to actuate pump 14, an alternating current signal is applied across an isolation transformer 15 having output terminals 16 and 171. Transmission line 12 is connected to output terminal 16 through a blocking diode 17 which is shunted by a switch 20 connected in parallel with the diode 17. Between terminal 16 and 171 are connected in series a resistor 21, a diode 22, a diode 23 and a resistor 24, with the mid-point between the diodes being illustrated as a point 25. It will be appreciated that in this configuration, diodes 22 and 23 are in a back-to-back configuration.

Transmission line 13 is connected through a relay coil 26 through multi-tap resistor. 27 to output terminal 171 of the isolation transformer 15. The purpose of the multi-tap resistor 27 is to provide for line impedence matching. Once the line impedence is known, a fixed resistor may be utilized in place of multi-tap resistor 27. Relay coil 26 is shunted by a diode 28 to prevent ringing. Relay coil 26 controls a normally open set of contacts which activate an indicator 32 responsive to the continued energization of relay coil 26. A potentiometer 34 is connected from transmission line 13 to terminal 171 through resistor 27 and the wiper arm of potentiometer 34 for purposes of adjusting the transmission line potential. Potentiometer 34 is adjusted to prevent minute or small amounts of voltage from falsely energizing relay coil 26, since the transmisssion lines carrying the electrical current are often energized or influenced by the proximity of transformers or highvoltage power lines. Potentiometer 34 is used to prevent such induced voltages from energizing relay coil 26. Since the total loop resistance varies, the setting of potentiometer 34 will vary with each installation.

A relay coil 36 is connected between earth ground and mid point 25 with this relay coil being shunted by a diode 37, to prevent ringing when the relay coil is de-energized. Relay coil 36 actuates a normally closed switch 39 into an open position so as to deactivate alarm 40 during normal operation of the subject systern.

Turning now to the remote station, a pair of face-toface diodes 42 and 43 are connected in series between transmission lines 12 and 13. A relay coil 44 is connected between the transmission line 12 and a midpoint 45 between the face-to-face diodes 42, 43. A further diode, diode 46, is connected between midpoint 45 and earth ground through either switch 47 or switch 48. Switch 47, in one embodiment, is acutated by the opening of a door at the remote station such that switch 47 is opened with the opening of the door and is closed with the closing of the door. Opening of the door will sound an alarm at 40 because of the consequent de-energization of coil 36, with the interruption of the earth ground connection path between the remote and control stations as will be described hereinafter. Switch 48 is a key-activated, pick-proof, switch which is manually closed with the turning of its key. This sets up a closed circuit with the door switch open 47 thus allowing the door to be opened by authorized personnel without setting off the alarm.

Relay coil 44 actutes normally open switch contact 50 to permit power to be delivered to pump 14. Pump 14, when in operation, mechanically closes switch 52 which connects relay 44 directly across lines 12 and 13.

In operation, the ac. circuit which includes relay coil 44 is open due to the blocking action of diode 17 for voltage of one polarity, and the shunting action of diode 42 prevents energization of coil 44 for voltages of the other polarity. Power from isolation transformer 15 is, however, provided across relay coil 44 when key switch 20 is first closed, thus unblocking diode 17. Upon actuation of switch 20, positive half cycles of current at terminal 171 are applied through diodes 28 and 43 to mid-point 45, and then to relay coil 44 and back through diode 17, still in a blocked state but now by-passed through closed switch 20, pass through closed switch 20 to complete the energization circuit of relay coil 44. This is turn actuates switch 50 into a closed position for supplying power to pump 14 or some other electromechanical device. When pump 14 is activated, switch 52 closes such that power from transmission line 13 is directly coupled to relay coil 26 during normal operation of the pump.

On the positive half cycle of alternating current from terminal 16 this positive going voltage is shunted by diode 42 to point 45 from whence it proceeds through diode 46 through either switch 47 or 48, through earth 4 ground to relay coil 36, and through this relay coil to mid-point 25. The potential at point 25 is delivered either through diode 22 and resistor 21 to terminal 16 of the isolation transformer or through diode 23 and resistor 24 to terminal 171. This action opens the normally closed contacts 39 so that alarm 40 is inhibited.

It will be appreciated that upon actuation of pump 14, relay coil 26 will be energized for causing indicator 32 to indicate normal operation of the system. Should an intruder cause switch 47 to be opened, relay coil 36 is de-energized and alarm 40 sounds. In one operative embodiment, the half-wave rectified voltage at point 45 at the remote station is at volts while the voltage at point 25 at the control station is 4 volts. In this manner, the same transformer is utilized to provide both the power for relay coil 44 and the power for relay coil 36 and the power for relay coil 26.

Referring to FIG. 2 in another embodiment, the subject system can be used for supervisory control of a valve 60 in a fluid transmission line 61 via a valve reversing solonoid 62. The operation of this valve reversing solonoid is similar to that described in aforementioned US. Pat. No. 2,932,014. In this embodiment, in which reference characters for elements in FIG. 2 correspond are compared to like elements in FIG. 1, an additional switch 63 is provided in line 13 with potentiometer 34, diode 28, relay coil 26, contacts 30 and indicator 32 removed from the circuit.

Additionally, switch 52 of FIG. 1 is removed from the circuit and a relay coil 64 is provided for the actuation of the valve reversing solonoid in a direction opposite to that which accompanies the energizing of relay coil 44. Additionally, a flow meter 65 is interposed in fluid transmission line 61 which repeatedly opens and closes a telemetry switch 66, which replaces switches 47 and 48. Switch 66 is opened and closed at a rate proportional to fluid flow in conduit 61. Switch 39 tracks the opening and closing of switch 66 during normal operation. The control station is also provided with a cumulative time indicator 67 which records the amount of time during a predetermined time interval that switch 66 is closed. In its most usual form, indicator 67 may take the form of a conventional integrating device. Since switch 66 is closed for a time period proportional to the volumetric flow in conduit 61, indicator 67 therefore indicates either the flow rate or indirectly the valve position. In this manner, the circuit of FIG. 2 functions as a telemetry circuit for indicating either valve position or fluid flow.

To further describe the operation of the circuit of FIG. 2, switch 20 and 63 are connected in parallel with diodes 17 and 68 respectively. At the remote station, a pair of relay coils 44 and 64 are connected in parallel with respective diodes 42 and 43. The relay coils may be of conventional type and are connected to solonoid 62 arranged in one condition to open valve 60 and in another condition to close valve 60. Relay coil 44 and solonoid 62 thus form one telemetric receiver while relay coil 64 and solonoid 62 form another telemetric receiver. I

When it is desired to open valve 60, switch 20 is closed. Then in those half cycles of the alternating voltage in which a positive voltage is applied to transmission line 13, assuming the diodes to be poled so as to pass current from left to right in the drawing, current will flow through diode 68, through diode 43, around diode 42 and through relay coil 44 and the closed contacts of switch 20.

Relay coil 44 now being energized, its contacts (not shown) close to cause solonoid 62 to assume a position in which valve 60 is open.

In alternate half cycles in which the voltage applied to transmission line 13 is negative, no current will flow, since current cannot pass through diode 68 and the latter cannot be bypassed since switch 63 is open. Furthermore, relay coil 44 is now short circuited by diode 42 so that this relay would not be energized even if current could flow in these last mentioned alternate half cycles. In short, during the half cycles in which the voltage applied to transmission line 13 is negative, relay coil 44 is not energized; but during half cycles in which the voltage applied to the transmission line 13 is positive, relay coil 44 will be energized or de-energized depending solely whether the contacts of switch are closed or open. Relay coil 44 should of course have sufficient shading as not to change its condition, or chatter during the interval between alternate half cycles of the alternating current while the switch is closed. p

If it is desired to move valve 60 to its closed position, switch 63 is closed. Thereupon during those half cycles in which the voltage applied to transmission line 12 is positive, current flows through diodes l7 and 42, around diode 43, through relay coil 64, through transmission line 13, around diode 68, and through the closed contacts of switch 63.

Relay coil 64 now being energized, its contacts (not shown) are closed to cause the electrical solonoid to assume a position which will effectively close valve 60. In the alternate half cycles in which the voltage applied to transmission line 12 is negative, no current will flow, even though switch 63 be held closed since current cannot pass through diode 17 and the latter cannot be bypassed since switch 20 is open. Furthermore, relay coil 64 is now short circuited by diode 43 so that this relay coil would not be energized even if current could flow in said alternate half cycles. Thus the operation of valve reversing solonoid 62 is controlled by the states of switches 20 or 63. The status of valve 60 is monitored by flow meter 65 so that indicator 67 indicates a fully open valve during maximum flow through conduit 61 and minimal flow when valve 60 is closed.

Obviously, the telemetry switch 66 can be activated by any one of a variety of sensing systems such that a predetermined condition at the remote station can be monitored through the transmission lines. This system is not sensitive to voltage changes in that it is a timedependent system as opposed to an amplitude dependent system as illustrated in the prior art. Additionally, as will be apparent, the solonoid 62 can be replaced with any device responsive to two different signals for performing the prescribed function. The diode arrangement is also beneficial in eliminating the necessity for expensive choke coils while at the same time providing the requisite operation of a supervisory system. Of course, the diodes may be replaced with any one of a number of conventional rectifying devices.

What is claimed is: V

l. A supervisory control system for use between a control station 10 and a remote station 11 connected by a pair of transmission lines 12, 13 carrying an ac. signal, comprising:

first rectifying means 42, 43 having an output terminal 45, said first rectifying means being connected across said transmission lines l2, 13 at said remote 1 station 11 for generating a rectified signal at said output terminal 45;

an electromechanical device 44 at said remote station connected between one of said transmission lines 12 and said output terminal 45;

second rectifying means 17 in said one transmission line 12 at said control station 10 for blocking positive-going signals from said remote station coming in on said one line 12;

means 20 for rendering said second rectifying means unblocking;

condition responsive switch means 47, 48 at said remote station 11 for selectively connecting said output terminal 45, to earth ground; and

means at said control station 10, including an earth ground connection 78 responsive to the selective connection and disconnection of said output terminal 45 to earth ground at the said remote station 11 for indicating the state of said condition responsive switch means 47, 48. 1

2'. The supervisory control system of claim 1 wherein said indicating means includes a relay coil, back-toback diodes connected in series across said transmission lines at said control station, means for connecting the mid-point between said back-to-back diodes to one end of said relay coil and means for connecting the other end of said relay coil to earth ground.

3. The supervisory control system of claim 1 wherein said first rectifying means includes a pair of face-toface diodes connected in series across said transmission lines at said remote station, the mid-point between said two diodes constituting said output terminal.

4. The supervisory control system of claim 3 wherein said condition responsive switch means includes a diode and a switch connected in series between said output terminal and earth ground.

5. The supervisory control system of claim 4 wherein said switch is opened responsively to a predetermined alarm condition.

6. The supervisory control system of claim 4 further including means at said remote station for sensing the magnitude of a predetermined condition and for closing said switch means for a time period over a predetermined time interval proportional to the magnitude of said predetermined condition, and wherein said indicating means includes means at said control station for indicating said time period.

7. The supervisory control system of claim 6 wherein said predetermined condition is fluid flow rate.

8. The supervisory control system of claim 1 and further including means responsive to current flow in said transmission lines for indicating the presence of said current flow.

9. The supervisory control system of claim 1 and further including an isolation transformer having a secondary winding connected across said transmission lines at said control station, and means for matching the impedance of said isolation transformer to the impedance of said transmission lines.

10. The supervisory control system of claim 9 further including back-to-back diodes connected across said secondary winding and a relay coil connected between the mid-point between said back-to-back diodes and earth ground.

11. A system for indicating at a control station an alarm condition existing at a remote location wherein said remote location and said control station are interconnected with a pair of transmission lines, comprising face-to-face diodes connected across said transmission lines at said remote location; alarm condition responsive means at said remote location for connecting the mid-point between said face-to-facc diodes to earth ground under normal operating conditions and for disconnecting said mid-point responsive to said alarm condition; back-to-back diodes connected across said transmission lines at said control station; and means connected between the mid-point between said backto-back diodes and earth ground for indicating current flow between earth ground and said last mentioned mid-point.

; 12. A supervisory control system for use between a control station and a remote station connected by a pair of transmission lines carrying an ac. signal, comprising: I

first rectifying means having an output terminal, said first rectifying means being connected across said transmission lines at said remote station for generating a half-wave rectified signal at said output terminal;

an electromechanical device at said remote station connected between one of said transmission lines and said output terminal;

second rectifying means in said one transmission line at said control station for blocking positive-going signals from said remote station coming in on said one line;

means for rendering said second rectifying means unblocking;

condition responsive switch means at said remote station for selectively connecting said output terminal to earth ground; and

means at said control station for indicating the state of said condition responsive switch means, said first rectifying means including a pair of face-to-face diodes connected in series across said transmission lines at said remote station, the mid-point between said two diodes constituting said output terminal, and further including means connected between said output terminal and the other of said transmission lines for providing a conducting path around the diode therebetween in response to the energization of said electromagnetic device with the rendering of said second rectifying means unblocking.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4487065 *Mar 7, 1983Dec 11, 1984Cypher SystemsStorage tank level monitoring apparatus and method therefor
US4551719 *Mar 7, 1983Nov 5, 1985Cypher SystemsOil field lease management and security system and method therefor
US4749338 *May 11, 1987Jun 7, 1988Webasto-Werk W. Baier Gmbh & Co.Side channel blower
US5091716 *Jul 10, 1990Feb 25, 1992Emco ElectronicsLiquid line leak detection method and apparatus
US8316695May 8, 2009Nov 27, 2012Delaware Capital Formation, Inc.Line leak detector and method of using same
US8850872Nov 10, 2011Oct 7, 2014Opw Fuel Management Systems, Inc.Line leak detector and method of using same
US20070163331 *Jan 16, 2007Jul 19, 2007Delaware Capital Formation, Inc.Line leak detector
US20100281953 *May 8, 2009Nov 11, 2010Delaware Capital Formation, Inc.Line leak detector and method of using same
DE4230585A1 *Sep 12, 1992Mar 17, 1994Bayerische Motoren Werke AgMonitoring unidirectional single wire interface - simulating earth short circuit interface fault when faulty information is received
DE4230585B4 *Sep 12, 1992Jun 23, 2005Bayerische Motoren Werke AgVerfahren zur Überwachung einer unidirektionalen Eindrahtschnittstelle
Classifications
U.S. Classification340/506, 340/870.9, 340/611, 340/538
International ClassificationG08C25/00
Cooperative ClassificationG08C25/00
European ClassificationG08C25/00