System and method for grounded-neutral fault detection

A method of detecting a ground fault, the method comprising:

• receiving a first signal from a first induction circuit, the first induction circuit configured to detect a current imbalance between a line conductor and a neutral conductor;
• determining a first frequency and a first phase of a noise signal component of the first signal;
• outputting a noise cancellation signal to a primary side of the first induction circuit, the noise cancellation signal having the first frequency of the noise signal component and an opposite phase than the first phase of the noise signal component;
• outputting a grounded neutral test signal while the noise cancellation signal is being output;
• and
• generating a trip signal based on determining that an impedance of the neutral conductor to ground is at or below a threshold level based upon the first signal received during the concurrent output of the noise cancelation signal and the grounded neutral test signal.

A fault detector, the fault detector comprising a processor, the processor being configured to operate the fault detector to:

• receive a first signal from a first induction circuit, the first induction circuit configured to detect a current imbalance between a line conductor and a neutral conductor;
• determine a first frequency and a first phase of a noise signal component of the first signal;
• output a noise cancellation signal to a primary side of the first induction circuit, the noise cancellation signal having the first frequency of the noise signal component and an opposite phase than the first phase of the noise signal component;
• and
• generate a trip signal based on a concurrent signal received by the processor.