An electrical fault detection device for use in a
branch of a power circuit that utilizes signals from an AC
line current sensor coupled to an electrical distribution line having a primary and neutral lines, a line high-frequency sensor coupled to the electrical distribution line, a differential
current sensor coupled to the primary and neutral lines, and a ground fault
current sensor coupled to the primary and neutral lines. A
signal conditioner receives the signals outputted by
AC current line current sensor, the line
high frequency sensor, the differential
current sensor and the ground fault current sensor and generates a
signal indicative of the load current associated with a
branch of the power circuit. Output of the
signal conditioner is sampled and processed by a
processing resource. The
processing resource has stored therein data representing a plurality of time-versus-current curves that define a plurality of regions in which
tripping may or may not occur. One region has
time data and current data that define a time-duration for a particular current magnitude for which no
tripping will occur. Another region has
time data and current data that define a time-duration of a particular current magnitude for which
tripping will occur.
Processing resource processes sampled signal to determine the region to which the processed
time data and current data correspond, and generates a signal to initiate tripping if the sampled signal yields a
time duration for a particular current magnitude that corresponds to a region for which tripping must occur.