Phase-Rotation Detector for Three-Phase Electrical Power System With Means to Detect Failure in Detector Circuit
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
A phase-rotation detector for a three-phase electrical power system has an improved input stage that forms pulses for each of two phases to neutral, arbitrarily phases A and B. The improved stage enables the circuit to operate from a wide range of line voltages, while maintaining low power dissipation. When phase rotation is correct, the pulse for phase A rises while the pulse for phase B is down. Conversely, if the phase rotation is incorrect the pulses rise in the reverse sequence: the pulse for phase A rises while the pulse for phase B is up. Three latches have their inputs connected to the A and B phase pulses to detect reverse phase rotation and certain other faults. One latch receives the phase A pulse at its data input and the phase B pulse at its clock input.