CA2195937A1 - Ac power outlet ground integrity and wire test circuit device - Google Patents
Ac power outlet ground integrity and wire test circuit deviceInfo
- Publication number
- CA2195937A1 CA2195937A1 CA002195937A CA2195937A CA2195937A1 CA 2195937 A1 CA2195937 A1 CA 2195937A1 CA 002195937 A CA002195937 A CA 002195937A CA 2195937 A CA2195937 A CA 2195937A CA 2195937 A1 CA2195937 A1 CA 2195937A1
- Authority
- CA
- Canada
- Prior art keywords
- hot
- neutral
- condition
- ground
- outlet
- 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
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/66—Testing of connections, e.g. of plugs or non-disconnectable joints
- G01R31/67—Testing the correctness of wire connections in electric apparatus or circuits
Abstract
A self-contained, plug-in, hand-held device for testing the current carrying ability of the Hot wire (12) and the Safety Ground return (CC) of standard AC
outlets (18) which have Hot connection (12), Neutral connection (16) and Ground connection (14). The test circuit device also detects common miswires and open connections in the AC outlet (18) being tested by way of flashing lights (D2, D4, D6) built into the tester circuit device. If the AC outlet (18) is wired correctly and the total resistance of the Hot line (10) and Safety Ground (CC) are below a predetermined limit, only one light "Green"
light (D4) meaning "OK" will flash, which use of only one light to indicate everything is properly wired makes the device easy to use even by a user with little knowledge of electrical testing devices and procedures. Various other detection conditions and indications of occurrence are afforded.
outlets (18) which have Hot connection (12), Neutral connection (16) and Ground connection (14). The test circuit device also detects common miswires and open connections in the AC outlet (18) being tested by way of flashing lights (D2, D4, D6) built into the tester circuit device. If the AC outlet (18) is wired correctly and the total resistance of the Hot line (10) and Safety Ground (CC) are below a predetermined limit, only one light "Green"
light (D4) meaning "OK" will flash, which use of only one light to indicate everything is properly wired makes the device easy to use even by a user with little knowledge of electrical testing devices and procedures. Various other detection conditions and indications of occurrence are afforded.
Description
WO 96139634 1 ~ T ~7 ~i ~J 3 7 ~ 14 AC POWER OUTLET GROUND ll.l....Hl'~'lr r~rl T!5~ r~T l~ VICE
FIEI~D OF T~ v ~n ~ N
t The present invention relates to device~ for monitoring and testing electrical power supply devlces, and more par~ic~ rly to and for a standard 3-~ire lZO volt AC electrlcal outlet, which assures the user that the outlet has been wlred properly and has acceptable groundlng properties.
P~ F T~E l~vt~n,lU~
For many years it has been known that the safety ground in AC
outlets in important, this ground connectlon will shunt current which can appear on the enclosure of the tool or appliance, due to a defect Ln insulation, harmlessly to ground. If the enclosure were not properly grounded and the hot wiring of the power tool were to short to the case, the user could suffer injury or death if he or she were standing on a surface which had a path to earth ground or were tourhing a surface which was connected to earth ground. If the tool being used were to develop such a fault and the outlet wiring was proper, a large amount of current would flow from the HOT wire of the AC oUtlet through the tool and back through the safety ground of the AC
outlet, thus PYcee~ng the current rating of the circuit breaker or fuse which protects the wiring and trippiny the breaker or blowing the fuse. It now becomes apparent that the total resistance of the HOT and SAFETY GROUND must have a value low enough to allow a current tPYrt2P~ing the rating of the circuit breaker or fuse to flow thus insuring that the power to the circuit will be interrupted due to such a fault.
Most 120 VAC circuit breakers have a rating of 20 amps. Using Ohms Law only, we find that the total resistance of the wiring from the main panel to the AC outlet and the connection from the AC outlet to earth ground must not exceed 6 ohms. If this total resistance is greater than 6 ohms, the breaker may not trip during a fault and a danyerous condition in terms of fire ha~ard SUBSTITUTE SHEET (RULE 26) WO96~9h~ 1~ ~~ l14 -~ 1 9 ~ 3 7 or ~hock will ~result. The potentlal for poor ~
conn~c~n~ to earth ground are the mo~t prevalent ~ince these connectlons arehusually made through the metalli~ condult which carries the wiring. This conduit typically has many couplings and connections throuqh ~unctlon ooxes between the AC outlets and the connectLon to earth grcund which usually termlnates at the power panel. In nddition to faulty asse~oly of these ground returns, the connections over time may loosen or corrodc causing the resistance to increese.
As shown in the example above, the total resistance of the circuit must not~be greater than 6 ohms. The most popular outlet tester on the market uses neon bulbs to indicate AC outlet miswires, these~lamps requiring only l or 2 mllliamperes to lLght or turn on. A faulty ground ccnnection having a resistance as high as 120,000 ohms will light the lamp in thls type of tester and the user will assume the outlet ls safe to use when it is not.
It becomes apparent that more than 1 or 2 ~il~ 3 iU
reSuired to properly exerclse these wiring connectlons, but a problem srises wlth ground fault Lnterrupter outlets. These outlets will trip if more than 3 m;l li~mr~res of current flow frcm the HOT WIRE and through the ground return of the outlet.
Thus, a tester ~which causes mcre than 1 m;ll~r -~s to flow through these wires during testlng is not usahle since the interrupter would trip every time it was tested. Applicant has found that the sclution to thi5 problem is to draw high current short duration pulses, currents ~Yres~ing zo amps may be drawn from the HOT WIR;E to EARTH GROU~D through the outlet without trippinq the interrupter, if the duration is short enough. A
total duration of 3 to 5 mi~ un~l~ with~ peak currents cf 20 amps or more will not trip these interrupters and the resistance of the wirinq can now be determined by detecting the amplltude of the current pulses- If the total resistance of the circuit is lower than a predetermined limit, the peak current will be high enouqh to triqger a light indicatinq the cutlet is safe to SU3SmlJTE 5HEET (RULE 26) W096~9~4 r~ L ~I 114 use .
, In view of that set forth above and other known ~ riPnr~ of the prior art for testing not only that an AC outlet ls properly wired but also to determine any defect ln the connection of the hot, neutral and ground wire connections, and further to detect a defective ground, the present invQntion prov~des the following advantages .
It is an object of the inventlon to provide a tester unit for detecting and indicating the o~ LL~nce of proper wiring of a tested AC outlet, a defective ground, an open Neutral, reversed Hot and Neutral connections, a connection wherein "Hot on Neutral with open Neutral" occurs, and an open Hot cnnnoctin~.
It is another object of the invention to agsure the user that the AC outlet has been wired properly and the total resi5tance of the Hot wire and the Ground return is below 6 ohms.
Various other objects and advantages of the present invention will be made known upon reading and understanding the detailed description of the invention which follows.
~V~I~RY OF T~IE INVENTION
The foregoing objects of the invention are achieved in an AC
POWER OUTLET GROUND lhl~L~Y AND ~IRING TESTER UNIT DEVICE AND
CIRCUIT having three LED' 5 "Red" "Green" and "Yellow", which LED's are actuated or energized to indicate any o~uLlen~e of proper and improper wiring connections of the Hot, Neutral, and Ground wires of the AC outlet, such being accomplished by operative circuitry including three relaxation oscillator circuits, each incorporating therein a LED indicator device to indicate the occurrence of a speciflc wiring condition, with all three of these oscillator circuits being contained in the tester unit/device and being connected between any of the Hot, Ground, and Neutral wiring connections of an AC outlet when the tester unit is plugged into the outlet.
SUBSTITUTE SHEET tRULE 26) ::
W09639634 F~u~ 4 3 5 '~ 3 7 BRIEY ~d~L~ LlUN OF ~HE DRA~INC
The novel ~eatures of the invention are set forth in the Appor ~
claims. The invention ltself wLll bs descrlbed wLth reference to the illustrative preferred ~ L depicted in the a~: _a~ nying FI5. 1 drawing.
~l~raTT.~n {1~,6~ U~l OF T~ I M
With reference to the FIG. 1 drawing there ls deplcted the electrical AC outlet monitoring and testing clrcuit devlce of the present invention. The tester 10 has three LED's D2 "Red", G4 NGreen", D6 "Yellow". Only the Green LED D4 will light or flash when the AC outlet is wired correct~y and the total resLstanoe of the ~OT WIRE~and Ground return is below 5 ohms. Each o~ the LED's, when lit or energized, will flash briefly several times a second. The chart oelow shows the various faults and flashins light co~inations for wiring ~aults that ~ay be accomplLshed oy the present invention.
L~'s FrA~T~ YL~
Green All Connectlons Okay Red Defectivs Ground Yellow & Green Open NeUtral Yellow 6 Red Reverse Hot ~ Neutral Yellow Hot On Neutral ~lth open Neutral None open Hot or Open Ground And Neutral The lnvention circuit simplicity, as shown in FIG. 1, will allow it to fit into a small hand-held, plug-in type enclosure, not shown. It is also self-powered from the AC l~ne (outlet). Power is supplled ~rom the Hot AC wire line 12 through Fuse Fl through Diode D1 and through current limiting reslstor R2 to capacitor Cl via clrcult line 13. The voltage capacltor Cl will charge to is limited to 15 volts which is controlled~by zencr diode D3 which is connected in series with resistor R4 to circuit common CC which is connected to the ~eutral wire line 1~ of the AC
SUBSTITUTE SHEE~ T (RULE 26~
W096~9~4 2 ~ 9 3 7 r~ 5~ 4 outlet 18 under test. The 15 volts appearing at the ~unction R2, D3, and Cl i5 ~ -c~L_d to a current llmiting resistor Rl whlch is ~o....e~Lad to LED D2 which i5 ~u.--.~tud to the anode o~ SCR Qi.
The cathode of Ql i5 ~u..,lec~ed to clrcuit com~on CC and the gate of Ql~is ~u..lle_Led to the iunction of D3 ~nd A4. When the unit is plugged into the AC power outlet and power i8 applied to the inVention circuitr the voltage acro55 Cl will cause current to flow through zener diode D3 and resistor R4. The current through R4 will cause a voltage PYc~e~ng .6 volt5 to be developed across it and this voltage will then cause a current to flow into the gate of SCR Ql whioh will cause Ql to conduct current and light o,r energize LED D2. LED D2 will remain on only briefly since the eneryy stored in capacitor Cl will be rapidly depleted and the current through Ql will fall below its holding current. When Ql turns off, due to the lack of sufficient holdinq current, the voltage across capacitor Cl wlll again begin to rise and the cycle will repeat. The circuit described so far is a complete self-contained first relaxatlon oscillator which will flash or light the LED DZ at a rate detorm~nod by the applied line voltage and the predetermined values of RZ, D3, R4 and Cl. The operation of this ~lrst relaxation oscillator will be inhiblted if the voltage across capacitor Cl is kept below the zener voltage of D3. ~his brings us to the 5econd part of the circuit: Resistor R3, LED D4, and SCR Q2, which are connected in series with each other between R2 and CC. This series circuit i5 ~ e~Pd across or in parallel with capacitor C1. If Q2 i5 triggered before the voltage across C1 reaches 15 volts, then LED D4 will flash ~be lit or energized intermittently~ rather than LED D2. QZ is triggered by the action of a second relaxation oscillator circuit comprised of diode Dl, SIDAC Q3, and the parallel combination of resistcr R5 and capacitor CZ which are coupled to the ground connection of the AC outlet 1~3 by way of a wire loop 19 around coil L~, and circuit line 20. This second relaxation oscillator will produce pulses at a predetermined rate two times that of the first relaxation oscillator mentioned above.
SUBSTITUTE SHEET (RUL~ 2~) W0 ~9634 F~a~ 4 5 ~ 7 ~
~hen power is applied to the tester 10, upon plug-ln to outlet 18, cspacitor C2 has no voltage acros5 it. The voltage no - ~, to cause SIDAC Q3 to breakdown Ls 120 volt~. Only the positive half cycles of~ the AC line voltage are p~assed by dlode D1 and J
when the positive half of the llne cycle reaches 120 volts, breakover devicc Q3 will become conductlve causing cnpacitor C2 to rapidly charge in about 4 ~i~.v-~u,-l~. At this tire, the curreht through Q3 will fall below it5 holdlng current and Q3 will turn off. C2 will now begin to d~charge through resi~tor R5 and when the voltaqe across C2 has fallen to a voltage low enough to allov 120 volts to again appear across Q3, the cycle will be repeated again. With the -~t v~lue~ shown in FIG.
1, Q3 will fire~approximately six (6) tlme5 a second. ~asically, the peak current that will flow i5 detorm~n~ by the forward drop of diode Dl, Q3 and the ESR of capacitor C2. Slnce these drops are very low, the main limit to the current flowlnq is the resistance of thQ AC wiring in outlet 1~. The current flowing through the loop 19 around coil Ll induc-s a voltage in coll L1 which volt ge i3 applied to the gate of Q2~"via circuit llnn 21"
which has a variable resistor connected from the gate of Q2 to circuit common CC. This resistor R6 aC~s a5 a currcnt shunt which controls the sensitivity of Q2, and R6 is set to prevent QZ from triygering if the peak currcnt puLse flowing in the loop 19 around coil~l is below a predetermined level. I~ Q2 is not triggered due to insufficient current being sensed by coil L1, then the prior described first relaxation osclllator will becone operative and the Red LED D2 wlll 5tart to flash indicating a defective ground.
Open Neutral Wire Condition: This brings U5 to the third relaxation oscillator circuit which is conflgured like the first relaxation oscillator circuit except that it is connected across the Neutral and around connections of the hC outlet under tcst, via wire lines ~4 and 16, and comprises: D5, R7, R8, C3, D7, R9, Q4, and LED D6 ~Yellow~. When the AC outlct is wired properly~
no potential di~fference exists across the5e two points (Neutral and Ground) and this third oscillator is lnoperative. If the SUBSmlJTE SHEET ~RULE 261 W096~9634 ~ 7 9 5 '~ 3 1 rc~ ~n s ( ll4 .
Neutral wire is open, the current flowing from the Circuit Com30n CC for the first 05cillator ~ust now flow through the third relaxation osCillator via D5 et al., to reach ground potential.
Thus, the first oscillator and the third 08cillator are placed in 5erie5 across the outlets' Hot and Ground lines- Since the second relaxation oscillator is operational causing the f~rst relaxation 05cillator to be inactlve, both the Green and Yellow LED's 04 and D6 will now flash or be lit at a predetermined rate.
Reversed Hot and Neutral wires condition: Upon detcotion of this condition, no potential difference will exlst across the second oscillator, and Q3 will not ~ire or conduct which will allow the Red LED D2 to flash or be lit at a predet~rm; n~d rate. The fact that Neutral is now Hot and Hot is now Neutral makes no difference to the first oscillator. Ihe Yellow 1FD D6 will also flash at a pre-set rate since the third oscillator will now be connected across 120 volts AC and because the Neutral wire will now be Hot.
Hot On Neutral With Open Neutral condition: Only the Yellow L~D
D6 will light or flash at a pre-set rate since only the third oscillator circuit will have 120 volts across it. Here it is assumed that the Hot part/wire of the AC outlet i9 open and no wire is connected to it.
No Liqhts Flashing Condition: For this to occur, the AC outlet 18 would have to be "dead" (no Hot connection) or both the Neutral and Ground connections would have to be "open" at the same ti~e.
It can now be seen from the foregoing disclosure that the present invention provides numerous advantages over the known prior art, and that the numerouS fault detectLon operatlons of the invention unit are accomplished via a single self-contained, small hand-held, pluq-in type, enclosure device which is powered from the AC line contained in the AC outlet under test.
SUBSTITUTE SHEET ~RULE 26) . .. _ .. . . _ .. .. . . _ , . . . . . .... . . .
WO 96/39634 ~ lL, .C 114
FIEI~D OF T~ v ~n ~ N
t The present invention relates to device~ for monitoring and testing electrical power supply devlces, and more par~ic~ rly to and for a standard 3-~ire lZO volt AC electrlcal outlet, which assures the user that the outlet has been wlred properly and has acceptable groundlng properties.
P~ F T~E l~vt~n,lU~
For many years it has been known that the safety ground in AC
outlets in important, this ground connectlon will shunt current which can appear on the enclosure of the tool or appliance, due to a defect Ln insulation, harmlessly to ground. If the enclosure were not properly grounded and the hot wiring of the power tool were to short to the case, the user could suffer injury or death if he or she were standing on a surface which had a path to earth ground or were tourhing a surface which was connected to earth ground. If the tool being used were to develop such a fault and the outlet wiring was proper, a large amount of current would flow from the HOT wire of the AC oUtlet through the tool and back through the safety ground of the AC
outlet, thus PYcee~ng the current rating of the circuit breaker or fuse which protects the wiring and trippiny the breaker or blowing the fuse. It now becomes apparent that the total resistance of the HOT and SAFETY GROUND must have a value low enough to allow a current tPYrt2P~ing the rating of the circuit breaker or fuse to flow thus insuring that the power to the circuit will be interrupted due to such a fault.
Most 120 VAC circuit breakers have a rating of 20 amps. Using Ohms Law only, we find that the total resistance of the wiring from the main panel to the AC outlet and the connection from the AC outlet to earth ground must not exceed 6 ohms. If this total resistance is greater than 6 ohms, the breaker may not trip during a fault and a danyerous condition in terms of fire ha~ard SUBSTITUTE SHEET (RULE 26) WO96~9h~ 1~ ~~ l14 -~ 1 9 ~ 3 7 or ~hock will ~result. The potentlal for poor ~
conn~c~n~ to earth ground are the mo~t prevalent ~ince these connectlons arehusually made through the metalli~ condult which carries the wiring. This conduit typically has many couplings and connections throuqh ~unctlon ooxes between the AC outlets and the connectLon to earth grcund which usually termlnates at the power panel. In nddition to faulty asse~oly of these ground returns, the connections over time may loosen or corrodc causing the resistance to increese.
As shown in the example above, the total resistance of the circuit must not~be greater than 6 ohms. The most popular outlet tester on the market uses neon bulbs to indicate AC outlet miswires, these~lamps requiring only l or 2 mllliamperes to lLght or turn on. A faulty ground ccnnection having a resistance as high as 120,000 ohms will light the lamp in thls type of tester and the user will assume the outlet ls safe to use when it is not.
It becomes apparent that more than 1 or 2 ~il~ 3 iU
reSuired to properly exerclse these wiring connectlons, but a problem srises wlth ground fault Lnterrupter outlets. These outlets will trip if more than 3 m;l li~mr~res of current flow frcm the HOT WIRE and through the ground return of the outlet.
Thus, a tester ~which causes mcre than 1 m;ll~r -~s to flow through these wires during testlng is not usahle since the interrupter would trip every time it was tested. Applicant has found that the sclution to thi5 problem is to draw high current short duration pulses, currents ~Yres~ing zo amps may be drawn from the HOT WIR;E to EARTH GROU~D through the outlet without trippinq the interrupter, if the duration is short enough. A
total duration of 3 to 5 mi~ un~l~ with~ peak currents cf 20 amps or more will not trip these interrupters and the resistance of the wirinq can now be determined by detecting the amplltude of the current pulses- If the total resistance of the circuit is lower than a predetermined limit, the peak current will be high enouqh to triqger a light indicatinq the cutlet is safe to SU3SmlJTE 5HEET (RULE 26) W096~9~4 r~ L ~I 114 use .
, In view of that set forth above and other known ~ riPnr~ of the prior art for testing not only that an AC outlet ls properly wired but also to determine any defect ln the connection of the hot, neutral and ground wire connections, and further to detect a defective ground, the present invQntion prov~des the following advantages .
It is an object of the inventlon to provide a tester unit for detecting and indicating the o~ LL~nce of proper wiring of a tested AC outlet, a defective ground, an open Neutral, reversed Hot and Neutral connections, a connection wherein "Hot on Neutral with open Neutral" occurs, and an open Hot cnnnoctin~.
It is another object of the invention to agsure the user that the AC outlet has been wired properly and the total resi5tance of the Hot wire and the Ground return is below 6 ohms.
Various other objects and advantages of the present invention will be made known upon reading and understanding the detailed description of the invention which follows.
~V~I~RY OF T~IE INVENTION
The foregoing objects of the invention are achieved in an AC
POWER OUTLET GROUND lhl~L~Y AND ~IRING TESTER UNIT DEVICE AND
CIRCUIT having three LED' 5 "Red" "Green" and "Yellow", which LED's are actuated or energized to indicate any o~uLlen~e of proper and improper wiring connections of the Hot, Neutral, and Ground wires of the AC outlet, such being accomplished by operative circuitry including three relaxation oscillator circuits, each incorporating therein a LED indicator device to indicate the occurrence of a speciflc wiring condition, with all three of these oscillator circuits being contained in the tester unit/device and being connected between any of the Hot, Ground, and Neutral wiring connections of an AC outlet when the tester unit is plugged into the outlet.
SUBSTITUTE SHEET tRULE 26) ::
W09639634 F~u~ 4 3 5 '~ 3 7 BRIEY ~d~L~ LlUN OF ~HE DRA~INC
The novel ~eatures of the invention are set forth in the Appor ~
claims. The invention ltself wLll bs descrlbed wLth reference to the illustrative preferred ~ L depicted in the a~: _a~ nying FI5. 1 drawing.
~l~raTT.~n {1~,6~ U~l OF T~ I M
With reference to the FIG. 1 drawing there ls deplcted the electrical AC outlet monitoring and testing clrcuit devlce of the present invention. The tester 10 has three LED's D2 "Red", G4 NGreen", D6 "Yellow". Only the Green LED D4 will light or flash when the AC outlet is wired correct~y and the total resLstanoe of the ~OT WIRE~and Ground return is below 5 ohms. Each o~ the LED's, when lit or energized, will flash briefly several times a second. The chart oelow shows the various faults and flashins light co~inations for wiring ~aults that ~ay be accomplLshed oy the present invention.
L~'s FrA~T~ YL~
Green All Connectlons Okay Red Defectivs Ground Yellow & Green Open NeUtral Yellow 6 Red Reverse Hot ~ Neutral Yellow Hot On Neutral ~lth open Neutral None open Hot or Open Ground And Neutral The lnvention circuit simplicity, as shown in FIG. 1, will allow it to fit into a small hand-held, plug-in type enclosure, not shown. It is also self-powered from the AC l~ne (outlet). Power is supplled ~rom the Hot AC wire line 12 through Fuse Fl through Diode D1 and through current limiting reslstor R2 to capacitor Cl via clrcult line 13. The voltage capacltor Cl will charge to is limited to 15 volts which is controlled~by zencr diode D3 which is connected in series with resistor R4 to circuit common CC which is connected to the ~eutral wire line 1~ of the AC
SUBSTITUTE SHEE~ T (RULE 26~
W096~9~4 2 ~ 9 3 7 r~ 5~ 4 outlet 18 under test. The 15 volts appearing at the ~unction R2, D3, and Cl i5 ~ -c~L_d to a current llmiting resistor Rl whlch is ~o....e~Lad to LED D2 which i5 ~u.--.~tud to the anode o~ SCR Qi.
The cathode of Ql i5 ~u..,lec~ed to clrcuit com~on CC and the gate of Ql~is ~u..lle_Led to the iunction of D3 ~nd A4. When the unit is plugged into the AC power outlet and power i8 applied to the inVention circuitr the voltage acro55 Cl will cause current to flow through zener diode D3 and resistor R4. The current through R4 will cause a voltage PYc~e~ng .6 volt5 to be developed across it and this voltage will then cause a current to flow into the gate of SCR Ql whioh will cause Ql to conduct current and light o,r energize LED D2. LED D2 will remain on only briefly since the eneryy stored in capacitor Cl will be rapidly depleted and the current through Ql will fall below its holding current. When Ql turns off, due to the lack of sufficient holdinq current, the voltage across capacitor Cl wlll again begin to rise and the cycle will repeat. The circuit described so far is a complete self-contained first relaxatlon oscillator which will flash or light the LED DZ at a rate detorm~nod by the applied line voltage and the predetermined values of RZ, D3, R4 and Cl. The operation of this ~lrst relaxation oscillator will be inhiblted if the voltage across capacitor Cl is kept below the zener voltage of D3. ~his brings us to the 5econd part of the circuit: Resistor R3, LED D4, and SCR Q2, which are connected in series with each other between R2 and CC. This series circuit i5 ~ e~Pd across or in parallel with capacitor C1. If Q2 i5 triggered before the voltage across C1 reaches 15 volts, then LED D4 will flash ~be lit or energized intermittently~ rather than LED D2. QZ is triggered by the action of a second relaxation oscillator circuit comprised of diode Dl, SIDAC Q3, and the parallel combination of resistcr R5 and capacitor CZ which are coupled to the ground connection of the AC outlet 1~3 by way of a wire loop 19 around coil L~, and circuit line 20. This second relaxation oscillator will produce pulses at a predetermined rate two times that of the first relaxation oscillator mentioned above.
SUBSTITUTE SHEET (RUL~ 2~) W0 ~9634 F~a~ 4 5 ~ 7 ~
~hen power is applied to the tester 10, upon plug-ln to outlet 18, cspacitor C2 has no voltage acros5 it. The voltage no - ~, to cause SIDAC Q3 to breakdown Ls 120 volt~. Only the positive half cycles of~ the AC line voltage are p~assed by dlode D1 and J
when the positive half of the llne cycle reaches 120 volts, breakover devicc Q3 will become conductlve causing cnpacitor C2 to rapidly charge in about 4 ~i~.v-~u,-l~. At this tire, the curreht through Q3 will fall below it5 holdlng current and Q3 will turn off. C2 will now begin to d~charge through resi~tor R5 and when the voltaqe across C2 has fallen to a voltage low enough to allov 120 volts to again appear across Q3, the cycle will be repeated again. With the -~t v~lue~ shown in FIG.
1, Q3 will fire~approximately six (6) tlme5 a second. ~asically, the peak current that will flow i5 detorm~n~ by the forward drop of diode Dl, Q3 and the ESR of capacitor C2. Slnce these drops are very low, the main limit to the current flowlnq is the resistance of thQ AC wiring in outlet 1~. The current flowing through the loop 19 around coil Ll induc-s a voltage in coll L1 which volt ge i3 applied to the gate of Q2~"via circuit llnn 21"
which has a variable resistor connected from the gate of Q2 to circuit common CC. This resistor R6 aC~s a5 a currcnt shunt which controls the sensitivity of Q2, and R6 is set to prevent QZ from triygering if the peak currcnt puLse flowing in the loop 19 around coil~l is below a predetermined level. I~ Q2 is not triggered due to insufficient current being sensed by coil L1, then the prior described first relaxation osclllator will becone operative and the Red LED D2 wlll 5tart to flash indicating a defective ground.
Open Neutral Wire Condition: This brings U5 to the third relaxation oscillator circuit which is conflgured like the first relaxation oscillator circuit except that it is connected across the Neutral and around connections of the hC outlet under tcst, via wire lines ~4 and 16, and comprises: D5, R7, R8, C3, D7, R9, Q4, and LED D6 ~Yellow~. When the AC outlct is wired properly~
no potential di~fference exists across the5e two points (Neutral and Ground) and this third oscillator is lnoperative. If the SUBSmlJTE SHEET ~RULE 261 W096~9634 ~ 7 9 5 '~ 3 1 rc~ ~n s ( ll4 .
Neutral wire is open, the current flowing from the Circuit Com30n CC for the first 05cillator ~ust now flow through the third relaxation osCillator via D5 et al., to reach ground potential.
Thus, the first oscillator and the third 08cillator are placed in 5erie5 across the outlets' Hot and Ground lines- Since the second relaxation oscillator is operational causing the f~rst relaxation 05cillator to be inactlve, both the Green and Yellow LED's 04 and D6 will now flash or be lit at a predetermined rate.
Reversed Hot and Neutral wires condition: Upon detcotion of this condition, no potential difference will exlst across the second oscillator, and Q3 will not ~ire or conduct which will allow the Red LED D2 to flash or be lit at a predet~rm; n~d rate. The fact that Neutral is now Hot and Hot is now Neutral makes no difference to the first oscillator. Ihe Yellow 1FD D6 will also flash at a pre-set rate since the third oscillator will now be connected across 120 volts AC and because the Neutral wire will now be Hot.
Hot On Neutral With Open Neutral condition: Only the Yellow L~D
D6 will light or flash at a pre-set rate since only the third oscillator circuit will have 120 volts across it. Here it is assumed that the Hot part/wire of the AC outlet i9 open and no wire is connected to it.
No Liqhts Flashing Condition: For this to occur, the AC outlet 18 would have to be "dead" (no Hot connection) or both the Neutral and Ground connections would have to be "open" at the same ti~e.
It can now be seen from the foregoing disclosure that the present invention provides numerous advantages over the known prior art, and that the numerouS fault detectLon operatlons of the invention unit are accomplished via a single self-contained, small hand-held, pluq-in type, enclosure device which is powered from the AC line contained in the AC outlet under test.
SUBSTITUTE SHEET ~RULE 26) . .. _ .. . . _ .. .. . . _ , . . . . . .... . . .
WO 96/39634 ~ lL, .C 114
2~q~1 ~
WLth respect w:ith the circuit ~/on_nt5 mentioned above and shown in FIG. =1: All resistor values are In ohm5 tl/- 5%) and 1/4 watt unle5~s otherwi~e noted, and all capacitors are in ufd.
(~/- 10%).
Although the invention has been describ*d wlth reference to a preferred em~odiment, this description is not meant to be con~LLued in a limiting sense. Var:ious modificatlons of the disclosed ~ho~i nt, as well as alternative emoo~ Ls of the invention, will~ become apparent to persons of skill in the art upon reference to the description of the lnvention. It is therefore conte~plated that the appended claims will cover such modifications that fall within the true scope of the invention.
SUBSTITUTESHEET(RULE26) ~
WLth respect w:ith the circuit ~/on_nt5 mentioned above and shown in FIG. =1: All resistor values are In ohm5 tl/- 5%) and 1/4 watt unle5~s otherwi~e noted, and all capacitors are in ufd.
(~/- 10%).
Although the invention has been describ*d wlth reference to a preferred em~odiment, this description is not meant to be con~LLued in a limiting sense. Var:ious modificatlons of the disclosed ~ho~i nt, as well as alternative emoo~ Ls of the invention, will~ become apparent to persons of skill in the art upon reference to the description of the lnvention. It is therefore conte~plated that the appended claims will cover such modifications that fall within the true scope of the invention.
SUBSTITUTESHEET(RULE26) ~
Claims (8)
1. A self-contained, hand-held, plug-in device for testing the current carrying ability of the Hot wire and the safety Ground return wire of a standard AC outlet having Hot, Neutral, and Ground wire connections comprising in combination:
circuit means for detecting the occurrences of any miswired connections of the Hot, Neutral and Ground connections of said AC outlet and for visually indicating such occurrences, said circuit means having a single indicator light means actuable to indicate both a proper wiring condition of the said AC outlet and the condition wherein the total resistance of said Hot wire connection and said Ground connection is below a predetermined ohmic resistance limit, and wherein said circuit means is powered by the Hot wire connection of the AC outlet under test and eliminates any need for an internal power supply for said device.
circuit means for detecting the occurrences of any miswired connections of the Hot, Neutral and Ground connections of said AC outlet and for visually indicating such occurrences, said circuit means having a single indicator light means actuable to indicate both a proper wiring condition of the said AC outlet and the condition wherein the total resistance of said Hot wire connection and said Ground connection is below a predetermined ohmic resistance limit, and wherein said circuit means is powered by the Hot wire connection of the AC outlet under test and eliminates any need for an internal power supply for said device.
2. The device of Claim 1 wherein said circuit means includes a first relaxation oscillator circuit connectable between the Hot and Neutral wire connections of the AC outlet under test and said single indicator light means, and further includes a second indicator light means actuable to indicate the occurrence of a defective ground condition and also the occurrence of a reversed Hot and Neutral connections condition of said AC outlet under test.
3. The device of Claim 2 wherein said circuit means further includes a second relaxation oscillator circuit connectable between said Hot and Ground connections, and connected across said first relaxation oscillator circuit, wherein said second relaxation oscillator controls the flashing pulse rate of the said single indicator light.
4. The device of Claim 3 wherein the said circuit means further includes a third relaxation oscillator circuit connectable between the Ground and Neutral wire connections of said AC outlet under test and having a third indicator light means actuable to indicate the occurrence of an open Neutral condition, a reversed Hot and Neutral condition, and a Hot on Neutral with open Neutral condition.
5. The device of Claim 4 wherein said circuit means and its relaxation oscillator circuits and plurality of indicator light means are inoperable upon detection of an open Hot condition, or an open Ground and an open Neutral condition, which inhibits the actuation of any of said indicator light means, thereby indicating that the AC outlet wiring under test is defective.
6. The device of Claim 5 wherein the said circuit means and its second and third relaxation oscillator circuits are operable upon detection of an open Neutral condition to actuate said single and said third indicator light means, and are further operable upon detection of said reversed Hot and Neutral condition to actuate said second and third indicator light means.
7. A method for testing the current carrying ability of the Hot wire and the safety Ground return wire of a standard AC outlet having Hot, Neutral and Ground wire connections comprising the steps of:
a) detecting via circuit means the occurrences of any miswired connections of the Hot, Neutral and Ground connections of said AC
outlet and visually indicating such occurrences;
b) detecting and indicating via a single indicator light means both a proper wiring condition of the said AC outlet and the condition wherein the total resistance of said Hot wire connection and said Ground wire connection is below a predetermined ohmic resistance limit: and c) powering said circuit means and said indicator light means from the Hot wire connection of the said AC outlet under test.
a) detecting via circuit means the occurrences of any miswired connections of the Hot, Neutral and Ground connections of said AC
outlet and visually indicating such occurrences;
b) detecting and indicating via a single indicator light means both a proper wiring condition of the said AC outlet and the condition wherein the total resistance of said Hot wire connection and said Ground wire connection is below a predetermined ohmic resistance limit: and c) powering said circuit means and said indicator light means from the Hot wire connection of the said AC outlet under test.
8. The method as defined in Claim 7 further including the steps of detecting and indicating the occurrence of a defective Ground condition, an open Neutral condition, a reversed Hot and Neutral condition, a Hot on Neutral with open Neutral condition, an open Hot condition, and an open Ground and Neutral condition, as each condition occurs in said AC outlet under test.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/457,236 | 1995-06-01 | ||
US08/457,236 US5625285A (en) | 1995-06-01 | 1995-06-01 | AC power outlet ground integrity and wire test circuit device |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2195937A1 true CA2195937A1 (en) | 1996-12-12 |
Family
ID=23815945
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002195937A Abandoned CA2195937A1 (en) | 1995-06-01 | 1996-05-29 | Ac power outlet ground integrity and wire test circuit device |
Country Status (9)
Country | Link |
---|---|
US (1) | US5625285A (en) |
EP (1) | EP0774124B1 (en) |
JP (1) | JPH10513569A (en) |
KR (1) | KR100459574B1 (en) |
CN (1) | CN1078948C (en) |
CA (1) | CA2195937A1 (en) |
DE (1) | DE69633655T2 (en) |
TW (1) | TW297174B (en) |
WO (1) | WO1996039634A1 (en) |
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-
1995
- 1995-06-01 US US08/457,236 patent/US5625285A/en not_active Expired - Lifetime
-
1996
- 1996-05-29 DE DE69633655T patent/DE69633655T2/en not_active Expired - Fee Related
- 1996-05-29 KR KR1019970700627A patent/KR100459574B1/en not_active IP Right Cessation
- 1996-05-29 WO PCT/IB1996/000714 patent/WO1996039634A1/en active IP Right Grant
- 1996-05-29 CA CA002195937A patent/CA2195937A1/en not_active Abandoned
- 1996-05-29 EP EP96922172A patent/EP0774124B1/en not_active Expired - Lifetime
- 1996-05-29 JP JP9500277A patent/JPH10513569A/en not_active Ceased
- 1996-05-29 CN CN95194506A patent/CN1078948C/en not_active Expired - Fee Related
- 1996-05-31 TW TW085106492A patent/TW297174B/zh active
Also Published As
Publication number | Publication date |
---|---|
DE69633655T2 (en) | 2006-03-09 |
EP0774124A4 (en) | 1998-08-19 |
CN1161748A (en) | 1997-10-08 |
EP0774124A1 (en) | 1997-05-21 |
TW297174B (en) | 1997-02-01 |
CN1078948C (en) | 2002-02-06 |
JPH10513569A (en) | 1998-12-22 |
US5625285A (en) | 1997-04-29 |
DE69633655D1 (en) | 2004-11-25 |
KR970705032A (en) | 1997-09-06 |
KR100459574B1 (en) | 2005-05-13 |
WO1996039634A1 (en) | 1996-12-12 |
EP0774124B1 (en) | 2004-10-20 |
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FZDE | Dead |