Ground fault interrupting system for HVAC equipment

A device for interrupting a supply of power to a branch circuit that supplies power to a load, the circuit including at least a line conductor(s) and a grounding conductor different from the line conductor(s), the device comprising:

• a first ground fault sensor for monitoring an amount of a first leakage current across the line conductor(s) and the grounding conductor, the amount of the first leakage current ignoring leakage current across the grounding conductor;
• a second ground fault sensor for monitoring an amount of a second leakage current of the load from the line conductor(s), the amount of the second leakage current taking into account leakage current across the grounding conductor;
• and
• a processor(s) configured to:
• detect for a ground fault on the branch circuit based on the amount of the first leakage current monitored by the first ground fault sensor;
• detect for a ground fault at the load due to excessive leakage current based on the amount of the second leakage current and an allowable/acceptable amount of leakage current for the load under normal operation;
• and
• to control an interruption of the supply of power to the branch circuit if the ground fault on the branch circuit or at the load is detected,
• wherein the processor(s) is further configured to:
• monitor a pilot signal across a pilot signal wire, which is connected to a pilot control circuit within an enclosure of the load, the control pilot circuit having an electrical component(s) with a predefined load profile that is connected between the pilot signal wire and the grounding conductor;
• detect an impedance of a load profile of the control pilot circuit between the pilot signal wire and the grounding conductor using the monitored pilot signal;
• detect the grounding conductor being open, broken or improperly connected if the detected impedance of the load profile differs from an acceptable range of impedance for the predefined load profile;
• and
• control an interruption of the supply of power to the branch circuit if the grounding conductor is open, broken or improperly connected.

A method of interrupting a supply of power to a branch circuit that supplies power to a load, the circuit including at least a line conductor(s) and a grounding conductor different from the line conductor(s), the method comprising:

• monitoring, via a first ground fault sensor, an amount of a first leakage current across the line conductor(s) and the grounding conductor, the amount of the first leakage current ignoring leakage current across the grounding conductor;
• monitoring, via a second ground fault sensor, an amount of a second leakage current of the load across the line conductor(s)), the amount of the second leakage current taking into account leakage current across the grounding conductor;
• detecting, via a processor(s), for a ground fault on the branch circuit based on the amount of the first leakage current monitored by the first ground fault sensor and a first threshold;
• detecting, via the processor(s), for a ground fault at the load due to excessive leakage current based on the amount of the second leakage current and a second threshold relating to an allowable/acceptable amount of leakage current for the load under normal operation;
• and
• controlling, via the processor(s), an interruption of the supply of power to the branch circuit if the ground fault on the branch circuit or at the load is detected,
• wherein the method further comprises:
• outputting a report(s) or notification(s) to a remote computer device or system via a communication device or to a local output device, the report(s) or notification(s) being associated with a monitored power, a status and/or diagnostics associated with the supply of power to the branch circuit or load,
• wherein the report(s) or notification(s) comprises a status notification to perform service or maintenance on the load or equipment associated therewith if the second leakage current is approaching an excessive or abnormal level.

A device for interrupting a supply of power to a branch circuit that supplies power to a load, the circuit including at least two line conductors and a grounding conductor different from the at least two line conductors, the device comprising:

• at least one ground fault sensor comprising:
• a first ground fault sensor for monitoring an amount of a first leakage current across the at least two line conductor(s) and the grounding conductor, the amount of the first leakage current ignoring leakage current across the grounding conductor, and/or
• a second ground fault sensor for monitoring an amount of a second leakage current of the load across the at least two line conductors, the amount of the second leakage current taking into account leakage current across the grounding conductor;
• a processor(s) configured to:
• detect for at least one type of ground fault, the processor being configured to detect for a ground fault on the branch circuit based on the amount of the first leakage current monitored by the first ground fault sensor, and/or to detect for a ground fault at the load due to excessive leakage current based on the amount of the second leakage current and an allowable/acceptable amount of leakage current for the load under normal operation;
• and
• to control an interruption of the supply of power to the branch circuit if the at least one type of ground fault is detected,
• wherein the processor(s) is further configured to:
• monitor a pilot signal across a pilot signal wire, which is connected to a pilot control circuit within an enclosure of the load, the control pilot circuit having an electrical component(s) with a predefined load profile that is connected between the pilot signal wire and the grounding conductor;
• detect an impedance of a load profile of the control pilot circuit between the pilot signal wire and the grounding conductor using the monitored pilot signal;
• detect the grounding conductor being open, broken or improperly connected if the detected impedance of the load profile differs from an acceptable range of impedance for the predefined load profile;
• and
• control an interruption of the supply of power to the branch circuit if the grounding conductor is open, broken or improperly connected.