Ground fault circuit interrupter using frequency recognition and measurement

1. A wiring device comprising:

an interrupting device electrically connecting one or more line terminals to one or more load terminals when the interrupting device is in a reset condition and disconnecting the line terminals from the load terminals when the interrupting device is in a tripped condition; and

a controller configured to,

determine a frequency of an input voltage at the one or more line terminals,

determine whether the frequency is within a predetermined range, and

when the frequency is within the predetermined range, perform a test of the wiring device.

2. The wiring device of claim 1 , wherein the test is at least one selected from a group consisting of a first test of the interrupting device at a first period of the frequency, and a second test of a fault detection circuit at a second period of the frequency.

3. The wiring device of claim 2 , wherein the first period and the second period are respectively located at a negative half-wave of the frequency.

4. The wiring device of claim 2 , wherein the first period of the frequency and the second period of the frequency are equal.

5. The wiring device of claim 1 , wherein the interrupting device includes a solenoid and a solenoid switch.

6. The wiring device of claim 5 , wherein the first test includes the steps of

outputting a control signal to activate the solenoid switch; and

measuring a current of the solenoid when the control signal is output.

7. The wiring device of claim 1 , further comprising a fault detection circuit, wherein the fault detection circuit includes a transformer and a detection controller.

8. The wiring device of claim 7 , wherein the second test includes the steps of

outputting a control signal to allow current to flow through the transformer; and

measuring an output of the detection controller when current is flowing through the transformer.

9. The wiring device of claim 1 , wherein determining the frequency includes counting the number of positive zero crossings of the input voltage over a predetermined time period.

10. The wiring device of claim 1 , wherein the controller is configured to filter the frequency, wherein filtering the frequency of the line voltage includes a low-pass filtering operation to remove noise.

11. A method of performing a self-test of a wiring device, the method including:

determining, via controller, a frequency of an input voltage;

determining, via the controller, whether the frequency of the input voltage is within a predetermined range; and

when the frequency is within the predetermined range, performing the self-test of the wiring device.

12. The method of claim 11 , wherein the self-test includes at least one selected from a group consisting of a first test of an interrupting device of the wiring device at a first period of the frequency, and a second test of a fault detection circuit of the wiring device at a second period of the frequency.

13. The method of claim 12 , wherein the first period and the second period are respectively located at a negative half-wave of the frequency.

14. The method of claim 12 , wherein the first period of the frequency and the second period of the frequency are equal.

15. The method of claim 11 , further comprising filtering the frequency, wherein filtering the frequency of the line voltage includes a low-pass filtering operation to remove noise.

16. The method of claim 11 , wherein the step of performing the first test includes

outputting a control signal to activate a solenoid switch; and

measuring a current of a solenoid when the control signal is output.

17. The method of claim 11 , wherein the step of performing the second test includes

outputting a control signal to allow current to flow through a transformer; and

measuring an output of the fault detection circuit when current is flowing through the transformer.

18. The method of claim 14 , further comprising determining end-of-life of the wiring device if at least one selected from the group consisting of the first test and the second test have failed a predetermined number of times.

19. The method of claim 18 , wherein the step of determining the frequency of the input voltage includes counting the number of positive zero crossings of the input voltage over a predetermined time period.

20. The method of claim 11 , further comprising switching a buzzer on and off at a predetermined rate when a fault is detected.