Circuit interrupt device fault duration monitor

A method of determining a duration of a fault event in a circuit interrupt protective device, the method comprising:

• sensing, at a sensor circuit of the circuit interrupt protective device, a current or a voltage waveform in the circuit interrupt protective device, the current or voltage waveform originating from an AC mains;
• acquiring, at an analog-to-digital converter (ADC) of the circuit interrupt protective device, the current or voltage waveform sensed by the sensor circuit;
• receiving, at a fault detection module of the circuit interrupt protective device, the current or voltage waveform acquired by the ADC, the fault detection module operable to detect a fault event based on the current or voltage waveform;
• and
• receiving, at a fault duration module of the circuit interrupt protective device, the current or voltage waveform acquired by the ADC, the fault duration module operable to obtain a duration of the fault event based on the current or voltage waveform;
• wherein the duration of the fault event is obtained by computing a second derivative for a portion of the current or voltage waveform, finding a local maximum or a local minimum for the portion of the current or voltage waveform, and setting the local maximum or the local minimum as a starting time or an ending time for the duration of the fault event.

A non-transitory computer-readable medium having computer-readable instructions stored thereon for determining a duration of a fault event in a circuit interrupt protective device, the computer-readable instructions, when executed by a processor, cause the processor to perform a process that:

• senses, at a sensor circuit of the circuit interrupt protective device, a current or a voltage waveform in the circuit interrupt protective device, the current or voltage waveform originating from an AC mains;
• acquires, at an analog-to-digital converter (ADC) of the circuit interrupt protective device, the current or voltage waveform sensed by the sensor circuit;
• receives, at a fault detection module of the circuit interrupt protective device, the current or voltage waveform acquired by the ADC, the fault detection module operable to detect a fault event based on the current or voltage waveform;
• and
• receives, at a fault duration module of the circuit interrupt protective device, the current or voltage waveform acquired by the ADC, the fault duration module operable to obtain a duration of the fault event based on the current or voltage waveform;
• wherein the duration of the fault event is obtained by computing a second derivative for a portion of the current or voltage waveform, finding a local maximum or a local minimum for the portion of the current or voltage waveform, and setting the local maximum or the local minimum as a starting time or an ending time for the duration of the fault event.