System of protection for electric power distribution failures

An electric power generation system, comprising:

• a source of electrical energy having at least three output phases;
• a load distribution bus;
• at least two electrically parallel power feeders conductively coupling each output phase of said source of electrical energy to said load distribution bus;
• a controller;
• a parallel feeder current sensor for each parallel power feeder sensing electrical current conducted therein, said parallel feeder current sensor producing an output parallel current sense signal proportional to the magnitude of the parallel feeder current sensed thereby;
• means coupling each parallel feeder current sensor to said controller for conducting said output parallel current sense signal thereto;
• and wherein said controller comprises
• a comparator having an input coupled to said parallel feeder current sensors by said coupling means and an output, said comparator comparing the magnitudes of said output parallel current sense signals per phase, said comparator generating a magnitude differential signal per phase, and
• protection logic circuitry processing said magnitude differential signals, said protection logic circuitry further generating a first output protection signal when any of said magnitude differential signals exceeds a predetermined threshold for a predetermined amount of time sufficient to indicate a high impedance fault on at least one of the parallel power feeders.

A method of protecting an electric power generation system having at least three phases and at least two parallel power feeders coupling each electrical phase of a source of electrical energy through a contactor device to a load distribution bus from distribution failures, comprising the steps of:

• sensing electrical current conducted by each parallel power feeder to produce an output parallel current sense signal proportional to the magnitude of the parallel feeder current sensed thereby;
• comparing the magnitude of said output parallel current sense signal for one parallel power feeder to the magnitude of said output parallel current sense signals for the other parallel power feeders for that electrical phase;
• and
• generating a first output protection signal when the magnitude of said output parallel current sense signal for any parallel power feeder differs from the magnitude of said output parallel current sense signal for any other parallel power feeder for that phase by at least an amount sufficient to indicate a high impedance fault on at least one of the parallel power feeders.