Multiple frequency ground fault protection

An apparatus comprising:

• a current sensor system configured to operatively couple with an AC power system and configured to provide a current sensor signal indicating a leakage current of the AC power system;
• at least one signal conditioning channel including one or more of discrete circuit components and integrated circuit components configured to condition the current sensor signal to provide a conditioned current sensor signal;
• an integrated circuit-based controller operatively coupled with the at least one signal conditioning channel and configured to receive the conditioned current sensor signal, the integrated circuit-based controller being configured to execute instructions stored in at least one non-transitory memory medium to determine at least one frequency value and at least one magnitude value of the conditioned current sensor signal, evaluate a trip condition in response to the at least one frequency value and the at least one magnitude value, and provide a fault trip signal in response to evaluation of the trip condition, wherein the integrated circuit-based controller is configured to evaluate the trip condition by determining a magnitude threshold in response to the at least one frequency value and evaluating the at least one magnitude value relative to the magnitude threshold;
• and
• a circuit breaker mechanism operatively coupled with the integrated circuit-based controller and configured to open a circuit of the AC power system in response to the fault trip signal.