Ground fault interrupter self test circuits and related methods
Implementations of ground fault circuit interrupter (GFCI) self-test circuits may include: a current transformer coupled to a controller, a silicon controlled rectifier (SCR) test loop coupled to the controller, a ground fault test loop coupled to the controller, and a solenoid coupled to the controller. The SCR test loop may be configured to conduct an SCR self-test during a first half wave portion of a phase and the ground fault test loop may be configured to conduct a ground fault self-test during a second half wave portion of a phase. An SCR may be configured to activate the solenoid to deny power to a load upon one of the SCR self-test or the ground fault self-test being identified as failing.
1. A ground fault circuit interrupter self-test circuit comprising:
a current transformer coupled to a controller;
a silicon controlled rectifier (SCR) test loop coupled to the controller;
a ground fault test loop coupled to the controller; and
a solenoid coupled to the controller;
wherein the SCR test loop is configured to conduct an SCR self-test during a first half wave portion of a phase and the ground fault test loop is configured to conduct a ground fault self-test during a second half wave portion of a phase;
wherein an SCR is configured to activate the solenoid to deny power to a load upon one of the SCR self-test or the ground fault self-test being identified as failing; and
wherein one of the ground fault self-test or the SCR self-test fails two or more consecutive times before the SCR activates the solenoid.
2. The circuit of claim 1 , wherein the circuit is half wave biased.
3. The circuit of claim 1 , wherein the circuit is configured to periodically test one of the current transformer, the solenoid, a rectifier diode circuit, a current limiter dropping resistor, or any combination thereof.
4. The circuit of claim 1 , wherein the circuit is configured to detect an AC zero cross condition using a phase sense circuit coupled with a half wave power supply to monitor a power supply pin current over a positive half cycle and a negative half cycle of the half wave power supply.
5. The circuit of claim 1 , wherein the circuit is configured to detect an open condition on a power supply pin using a supply sense circuit coupled with a switch coupled with a phase pin to turn on the SCR and activate the solenoid when the supply sense circuit detects a floating condition or a no good bias condition at the power supply pin.
6. The circuit of claim 5 , wherein the supply sense circuit comprises a single diode coupled with a limiting resistor, the limiting resistor coupled with the power supply pin.
7. A ground fault interrupter self-test circuit comprising:
a silicon controlled rectifier (SCR) test loop coupled to a controller;
a ground fault test loop coupled to the controller; and
a solenoid coupled to the controller;
wherein the SCR test loop is configured to conduct an SCR self-test during a first half wave portion of a phase and the ground fault test loop is configured to conduct a ground fault self-test during a second half wave portion of a phase; and
wherein an SCR is configured to activate the solenoid and deny power to a load upon one of the SCR self-test or the ground fault self-test being identified as failing two or more consecutive times.
8. The circuit of claim 7 , wherein the circuit is half wave biased.
9. The circuit of claim 7 , wherein one of the ground fault self-test or the SCR self-test are repeatedly performed after passage of a predetermined period of time while the circuit is coupled with an electrical power supply.
10. The circuit of claim 7 , wherein the circuit is configured to periodically test one of a current transformer, the solenoid, a rectifier diode circuit, a current limiter dropping resistor, or any combination thereof.
11. The circuit of claim 7 , wherein the circuit is configured to detect an AC zero cross condition using a phase sense circuit coupled with a half wave power supply to monitor a power supply pin current over a positive half cycle and a negative half cycle of the half wave power supply.
12. The circuit of claim 7 , wherein the circuit is configured to detect an open condition on a power supply pin using a supply sense circuit coupled with a switch coupled with a phase pin to turn on the SCR and activate the solenoid when the supply sense circuit detects a floating condition or a no good bias condition at the power supply pin.
13. The circuit of claim 12 , wherein the supply sense circuit comprises a single diode coupled with a limiting resistor, the limiting resistor coupled with the power supply pin.
14. A method of self-testing a ground fault interrupter circuit comprising:
consecutively testing for a ground fault in a ground fault interrupter circuit during a first half wave portion of a phase;
consecutively testing a silicon controlled rectifier (SCR) in the ground fault interrupter circuit during a second half wave portion of the phase; and
placing the ground fault interrupter circuit in an end of life stage if one of testing for the ground fault or testing the SCR results in consecutively failed tests.
15. The method of claim 14 , wherein the testing for the ground fault and the testing of the SCR occur within a second of powering the ground fault interrupter circuit.
16. The method of claim 15 , wherein the testing for the ground fault and the testing of the SCR is completed within five seconds of powering the ground fault interrupter circuit.
17. The method of claim 14 , further comprising placing the ground fault interrupter circuit in the end of life stage if one of testing a current transformer, a solenoid, a rectifier diode circuit, a current limiter dropping resistor, or any combination thereof results in a failed test.
18. The method of claim 14 , further comprising detecting an AC zero cross condition using a phase sense circuit coupled with a half wave power supply to monitor a power supply pin current over a positive half cycle and a negative half cycle of the half wave power supply.
19. The method of claim 14 , further comprising detecting an open condition on a power supply pin using a supply sense circuit coupled with a switch coupled with a phase pin to turn on the SCR and activate a solenoid when the supply sense circuit detects a floating condition or a no good bias condition at the power supply pin.