Patent ID: 8035944

Claim:
A three-phase power supply system, comprising: an AC/DC converter having a three phase power input coupled through three fuses to three legs of three phase AC power (Phase A, Phase B, Phase C), an output coupled to a DC bus, and a control input coupled to an output of a control module; the three phase input power having input components including current and voltage, the control module generating three arrays of data for one of the input components, one array for each of the three phases of the three phase input power including a Phase A sample data array for a Phase A component of the input component, a Phase B sample data array for a Phase B component of the input component, and a Phase C sample data array for a Phase C component of the input component; the control module generating a negative sequence of the input component for which it generated the data arrays by taking one third of the sum of point I a , point I b . and point I c , where point I a is a datum in the Phase A data array when the negative sequence is being determined, point I b . is a datum point in the line cycle that is 240 degrees delayed from the point I a , and point I c is a datum point in the line cycle that is 120 degrees delayed from the point I a , and the control module determining that an input fuse is blown if the value of the negative sequence of the input component exceeds a threshold.