INTELLIGENT LIFE TESTING METHODS AND APPARATUS FOR LEAKAGE CURRENT PROTECTION

• US 20070164750A1
• Filed: 10/26/2006
• Published: 07/19/2007
• Est. Priority Date: 12/26/2005
• Status: Active Grant

• Current Assignee: Heng Chen
• Original Assignee: General Protecht Group Incorporated
• Inventors: Wang, Fu, Chen, Wusheng, Wang, Lianyun
• Granted Patent: US 7,268,559 B1
• Time in Patent Office: Days
• US Class Current: 324/527
• CPC Class Codes: G01R 31/3278 of relays, solenoids or reed switches measuring contact resistance G01R27/205; high voltage magnetic switches G01R31/3271, G01R31/333; testing electric windings G01R31/72; monitoring of fail safe circuits H01H47/002
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02H 3/335 the main function being self testing of the device

Abstract

An apparatus for testing the life of a leakage current protection device having a leakage current detection circuit. In one embodiment, the apparatus a trip mechanism state generator, a fault alarm generator, a ground fault simulation unit. In operation, the ground fault simulation unit generates a simulated ground fault signal during every positive half-wave of an AC power, the simulated ground fault signal is detected by the leakage current detection circuit, the leakage current detection circuit responsively generates a signal to turn a switching device into its conductive state so as to allow a current to pass therethrough, the passed current is converted into a DC voltage in accordance with a trip mechanism state generated by the trip mechanism state generator, the fault alarm circuit receives and analyzes the DC voltage and indicates whether a fault exists in the leakage current protection device.

Claims

1. An apparatus for testing the life of a leakage current protection device, wherein the leakage current protection device has a first inductive coil N1, a second inductive coil N2, a first input, a second input, a first output electrically coupled to the second input through the first inductive coil N1 and the second inductive coil N2, a second output, a third output, a trip switch SW101 having two LINE terminals and electrically coupled to the first input and the second input, respectively, for receiving an AC power, and two LOAD terminals and electrically coupled to the inputs of an electrical appliance, respectively, a power supply circuit having an input electrically coupled to the first input, and an output electrically coupled to the second output, a trip coil circuit having a switching device VD1 having a gate, an anode and a cathode, an input, an output electrically coupled to the third output, and a leakage current detection circuit having an output electrically coupled to the input of the trip coil circuit, and a power supply inputp electrically coupled to the output of the power supply circuit and the second output, comprising:

(i) a trip mechanism state generator having a first input electrically coupled to the third output of the leakage current protection device, a second input electrically coupled to the first input of the leakage current protection device, a third input electrically coupled to the second input of the leakage current protection device, a first output and a second output, wherein the trip mechanism state generator is adapted for generating a trip mechanism state at the first output and the second output, wherein the trip mechanism state has a first state and a second state, and wherein when the trip mechanism state is in the first state, there is no fault exist in the leakage current protection device, and wherein the trip mechanism state is in the second state, there is at least one fault exists in the leakage current protection device;

(ii) a fault alarm generator having a first input electrically coupled to the first output of the trip mechanism state generator, a second input electrically coupled to the second output of the trip mechanism state generator, and a power supply input electrically coupled to the second output of the leakage current protection device; and

(iii) a ground fault simulation unit having an input electrically coupled to the first input of the leakage current protection device, and an output electrically coupled to the first output of the leakage current protection device,

wherein, in operation, the ground fault simulation unit generates a simulated ground fault signal during every positive half-wave of the AC power, the simulated ground fault signal is detected by the leakage current detection circuit, the leakage current detection circuit responsively generates a signal to turn the switching device VD1 into its conductive state so as to allow a current to pass therethrough, the passed current is converted into a DC voltage in accordance with a trip mechanism state generated by the trip mechanism state generator, the fault alarm circuit receives and analyzes the DC voltage and indicates whether a fault exists in the leakage current protection device.

2. The apparatus of claim 1, wherein the trip mechanism state generator comprises:

(i) a first diode D1 having a cathode and an anode electrically coupled to the second input of the trip mechanism state generator;

(ii) a second diode D2 having a cathode electrically coupled to the cathode of the first diode D1 and the first input of the trip mechanism state generator, and an anode electrically coupled to the third input of the trip mechanism state generator;

(iii) a third diode D3 having an anode and a cathode electrically coupled to the second input of the leakage current protection device and the anode of the second diode D2;

(iv) a fourth diode D4 having a cathode electrically coupled to the anode of the first diode D1 and the first input of the leakage current protection device, and an anode electrically coupled to a first output of the trip mechanism state generator;

(v) a fifth resistor R5 having a first terminal electrically coupled to the first output of the trip mechanism state generator, and a second terminal electrically coupled to the second output; and

(vi) a sixth resistor R6 having a first terminal electrically coupled to the second terminal of the fifth resistor R5 and the second output of the trip mechanism state generator, and a second terminal electrically coupled to the anode of the third diode D3.

3. The apparatus of claim 2, the DC voltage is detected at the first terminal and the second terminal of the resistor R5.

4. The apparatus of claim 3, wherein the DC voltage is a negative voltage if there is no fault in the leakage current protection device, and wherein the DC voltage is a positive voltage if there is at least one fault in the leakage current protection device.

5. The apparatus of claim 4, wherein the fault alarm circuit comprises a multi-vibrator having a light emitting diode (LED) D8, wherein the multi-vibrator generates no vibration indicating that there is no fault in the leakage current protection device when the fault alarm circuit receives a negative DC voltage, and wherein the multi-vibrator generates vibrations and a visible alarm through the LED D8 indicating that there is at least one fault in the leakage current protection device when the fault alarm circuit receives a positive DC voltage.

6. The apparatus of claim 5, wherein the fault alarm circuit comprises an audio alarm circuit for generating an audible alarm.

7. The apparatus of claim 1, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and a second terminal;

(ii) a second resistor R2 having a first terminal and a second terminal;

(iii) a third resistor R3 having a first terminal and a second terminal;

(iv) a seventh diode D7 having a cathode and an anode, wherein the anode of the seventh diode D7 is connected to the input that is electrically coupled a hot wire of the AC power, and the cathode of the seventh diode D7 is connected to both the first terminal of the resistor R1 and the first terminal of the second resistor R2;

(iv) a first transistor Q1 having a first collector electrically coupled to the second terminal of the first resistor R1, a first emitter electrically coupled to both the second terminal of the third resistor R3 and the output, and a first base; and

(iii) a sixth zener diode D6 having an anode electrically coupled to the base of the first transistor Q1, and a cathode electrically coupled to both the second terminal of the second resistor R2 and the first terminal of the third resistor R3.

8. The apparatus of claim 1, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and a second terminal;

(ii) a second resistor R2 having a first terminal and a second terminal;

(iii) a third resistor R3 having a first terminal and a second terminal electrically coupled to the second output2;

(iv) a seventh diode D7 having an anode electrically coupled to the input of the ground fault simulation unit, and a cathode electrically coupled to both the first terminal of the first resistor R1 and the first terminal of the second resistor R2;

(v) a first transistor Q1 having a first collector electrically coupled to the second terminal of the first resistor R1, a first emitter electrically coupled to the second input of the leakage current protection device, and a base; and

(iv) a sixth zener diode D6 having an anode electrically coupled to the base of the first transistor Q1, and a cathode electrically coupled to both the second terminal of the second resistor R2 and the first terminal of the third resistor R3.

9. The apparatus of claim 1, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and a second terminal;

(ii) a seventh diode D7 having an anode electrically coupled to the input, and a cathode electrically coupled to the first terminal of the resistor R1; and

(ii) a transformer T1 having a primary winding having a first primary terminal P1 and a second primary terminal P2, and a secondary winding having a first secondary terminal S1 and a second secondary terminal S2, wherein the first primary terminal P1 is electrically coupled to the second terminal of the first resistor R1, the second primary terminal P2 is electrically coupled to the second input of the leakage current protection device, the first secondary terminal S1 is electrically coupled to the second secondary terminal S2 through the first inductive coil N1 and the second inductive coil N2.

10. The apparatus of claim 1, wherein the ground fault simulation unit comprises:

(i) a seventh diode D7 having a cathode and an anode electrically coupled to the input; and

(ii) a first resistor R1 having a first terminal electrically coupled to the cathode of the seventh diode D7, and a second terminal electrically coupled to the output.

11. The apparatus of claim 1, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and second terminal;

(ii) a seventh diode D7 having an anode electrically coupled to the input, and a cathode electrically coupled to the first terminal of the first resistor R1; and

(iii) a sixth zener diode D6 having a cathode electrically coupled to the second terminal of the first resistor R1, and an anode electrically coupled to the output.

12. A method for intelligently testing the life of a leakage current protection device, wherein the leakage current protection device has a first inductive coil N1, a second inductive coil N2, a first input, a second input, a first output electrically coupled to the second input through the first inductive coil N1 and the second inductive coil N2, a second output, a third output, a trip switch SW101 having two LINE terminals and electrically coupled to the first input and the second input, respectively, for receiving an AC power, and two LOAD terminals and electrically coupled to the inputs of an electrical appliance, respectively, a power supply circuit having an input electrically coupled to the first input, and an output electrically coupled to the second output, a trip coil circuit having a switching device VD1 having a gate, an anode and a cathode, an input, an output electrically coupled to the third output, and a leakage current detection circuit having an output electrically coupled to the input of the trip coil circuit, and a power supply inputp electrically coupled to the output of the power supply circuit and the second output, comprising the steps of:

(i) providing a testing device having;

(a) a trip mechanism state generator having a first input electrically coupled to the third output of the leakage current protection device, a second input electrically coupled to the first input of the leakage current protection device, a third input electrically coupled to the second input of the leakage current protection device, a first output and a second output, wherein the trip mechanism state generator is adapted for generating a trip mechanism state at the first output and the second output, wherein the trip mechanism state has a first state and a second state, and wherein when the trip mechanism state is in the first state, there is no fault exist in the leakage current protection device, and wherein the trip mechanism state is in the second state, there is at least one fault exists in the leakage current protection device;

(b) a fault alarm generator having a first input electrically coupled to the first output of the trip mechanism state generator, a second input electrically coupled to the second output of the trip mechanism state generator, and a power supply input electrically coupled to the second output of the leakage current protection device; and

(c) a ground fault simulation unit having an input electrically coupled to the first input of the leakage current protection device, and an output electrically coupled to the first output of the leakage current protection device,

(ii) generating a simulated ground fault signal during every positive half-wave of the AC power by the ground fault simulation unit;

(iii) detecting the simulated ground fault signal at the leakage current detection circuit;

(iv) generating a signal to turn the switching device VD1 into its conductive state so as to allow a current to pass therethrough;

(v) generating a DC voltage in responsive to a trip mechanism state at the trip mechanism state generator, wherein the trip mechanism state is in a first state that there is no fault exist in the leakage current protection device, or in a second state that there is at least one fault exists in the leakage current protection device;

(vi) receiving the DC voltage at the fault alarm circuit; and

(vii) indicating whether at least one fault exists in the leakage current protection device.

13. The method of claim 12, wherein the indicating step comprises the step of producing a visible alarm.

14. The method of claim 13, wherein the indicating step further comprises the step of producing an audible alarm.

15. A leakage current protection device with intelligent life testing, comprising:

(I) a leakage current protection device having;

(a) a first inductive coil N1;

(b) a second inductive coil N2;

(c) a first input;

(d) a second input;

(e) a first output electrically coupled to the second input through the first inductive coil N1 and the second inductive coil N2;

(f) a second output;

(g) a third output;

(h) a trip switch SW101 having two LINE terminals and electrically coupled to the first input and the second input, respectively, for receiving an AC power, and two LOAD terminals and electrically coupled to the inputs of an electrical appliance, respectively;

(i) a power supply circuit having an input electrically coupled to the first input, and an output electrically coupled to the second output;

(j) a trip coil circuit having a switching device VD1 having a gate, an anode and a cathode, an input, and an output electrically coupled to the third output; and

(k) a leakage current detection circuit having an output electrically coupled to the input of the trip coil circuit, and a power supply inputp electrically coupled to the output of the power supply circuit and the second output;

(II) a trip mechanism state generator having a first input electrically coupled to the third output of the leakage current protection device, a second input electrically coupled to the first input of the leakage current protection device, a third input electrically coupled to the second input of the leakage current protection device, a first output and a second output, wherein the trip mechanism state generator is adapted for generating a trip mechanism state at the first output and the second output, wherein the trip mechanism state has a first state and a second state, and wherein when the trip mechanism state is in the first state, there is no fault exist in the leakage current protection device, and wherein the trip mechanism state is in the second state, there is at least one fault exists in the leakage current protection device;

(III) a fault alarm generator having a first input electrically coupled to the first output of the trip mechanism state generator, a second input electrically coupled to the second output of the trip mechanism state generator, and a power supply input electrically coupled to the second output of the leakage current protection device; and

(IV) a ground fault simulation unit having an input electrically coupled to the first input of the leakage current protection device, and an output electrically coupled to the first output of the leakage current protection device,

wherein, in operation, the ground fault simulation unit generates a simulated ground fault signal during every positive half-wave of the AC power, the simulated ground fault signal is detected by the leakage current detection circuit, the leakage current detection circuit responsively generates a signal to turn the switching device VD 1 into its conductive state so as to allow a current to pass therethrough, the passed current is converted into a DC voltage in accordance with a trip mechanism state generated by the trip mechanism state generator, the fault alarm circuit receives and analyzes the DC voltage and indicates whether a fault exists in the leakage current protection device.

16. The leakage current protection device of claim 15, wherein the trip mechanism state generator comprises:

(i) a first diode D1 having an anode electrically coupled to the second input of the trip mechanism state generator, and a cathode;

(ii) a second diode D2 having a cathode electrically coupled to the cathode of the first diode D1 and the first input of the trip mechanism state generator, and an anode electrically coupled to the third input of the trip mechanism state generator;

(iii) a third diode D3 having a cathode electrically coupled to the second input of the leakage current protection device and the anode of the second diode D2, and an anode;

(iv) a fourth diode D4 having a cathode electrically coupled to the anode of the first diode D1 and the first input of the leakage current protection device, and an anode electrically coupled to a first output of the trip mechanism state generator;

(v) a fifth resistor R5 having a first terminal electrically coupled to the first output of the trip mechanism state generator, and a second terminal electrically coupled to the second output; and

(vi) a sixth resistor R6 having a first terminal electrically coupled to the second terminal of the fifth resistor R5 and the second output of the trip mechanism state generator, and a second terminal electrically coupled to the anode of the third diode D3.

17. The leakage current protection device of claim 16, the DC voltage is detected at the first terminal and the second terminal of the resistor R5.

18. The leakage current protection device of claim 17, wherein the DC voltage is a negative voltage if there is no fault in the leakage current protection device, and the DC voltage is a positive voltage if there is at least one fault in the leakage current protection device.

19. The leakage current protection device of claim 18, wherein the fault alarm circuit comprises a multi-vibrator having a light emitting diode (LED) D8, wherein the multi-vibrator generates no vibration indicating there is no fault in the leakage current protection device if the fault alarm circuit receives the negative DC voltage, and generates a vibration and a visible alarm through the LED D8 indicating there is at least one fault in the leakage current protection device if the fault alarm circuit receives the positive DC voltage.

20. The leakage current protection device of claim 19, wherein the fault alarm circuit comprises an audio alarm circuit for generating an audible alarm.

21. The leakage current protection device of claim 15, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and a second terminal;

(ii) a second resistor R2 having a first terminal and a second terminal;

(iii) a third resistor R3 having a first terminal and a second terminal;

(iv) a seventh diode D7 having a cathode and an anode, wherein the anode of the seventh diode D7 is connected to the input that is electrically coupled a hot wire of the AC power, and the cathode of the seventh diode D7 is connected to both the first terminal of the resistor R1 and the first terminal of the second resistor R2;

(iv) a first transistor Q1 having a first collector electrically coupled to the second terminal of the first resistor R1, a first emitter electrically coupled to both the second terminal of the third resistor R3 and the output, and a first base; and

(iii) a sixth zener diode D6 having an anode electrically coupled to the base of the first transistor Q1, and a cathode electrically coupled to both the second terminal of the second resistor R2 and the first terminal of the third resistor R3.

22. The leakage current protection device of claim 15, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and a second terminal;

(ii) a second resistor R2 having a first terminal and a second terminal;

(iii) a third resistor R3 having a first terminal and a second terminal electrically coupled to the second output2;

(iv) a seventh diode D7 having an anode electrically coupled to the input of the ground fault simulation unit, and a cathode electrically coupled to both the first terminal of the first resistor R1 and the first terminal of the second resistor R2;

(v) a first transistor Q1 having a first collector electrically coupled to the second terminal of the first resistor R1, a first emitter electrically coupled to the second input of the leakage current protection device, and a base; and

(iv) a sixth zener diode D6 having an anode electrically coupled to the base of the first transistor Q1, and a cathode electrically coupled to both the second terminal of the second resistor R2 and the first terminal of the third resistor R3.

23. The leakage current protection device of claim 15, wherein the ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and a second terminal;

(ii) a seventh diode D7 having an anode electrically coupled to the input, and a cathode electrically coupled to the first terminal of the resistor R1; and

(ii) a transformer T1 having a primary winding having a first primary terminal P1 and a second primary terminal P2, and a secondary winding having a first secondary terminal S1 and a second secondary terminal S2, wherein the first primary terminal P1 is electrically coupled to the second terminal of the first resistor R1, the second primary terminal P2 is electrically coupled to the second input of the leakage current protection device, the first secondary terminal S1 is electrically coupled to the second secondary terminal S2 through the first inductive coil N1 and the second inductive coil N2.

24. The leakage current protection device of claim 15, wherein the ground fault simulation unit comprises:

(i) a seventh diode D7 having a cathode and an anode electrically coupled to the input; and

(ii) a first resistor R1 having a first terminal electrically coupled to the cathode of the seventh diode D7, and a second terminal electrically coupled to the output.

25. The leakage current protection device of claim 15, wherein the-ground fault simulation unit comprises:

(i) a first resistor R1 having a first terminal and second terminal;

(ii) a seventh diode D7 having an anode electrically coupled to the input, and a cathode electrically coupled to the first terminal of the first resistor R1; and

(iii) a sixth zener diode D6 having a cathode electrically coupled to the second terminal of the first resistor R1, and an anode electrically coupled to the output.