Lead-Lag Phase-Angle Monitor and Phase-Sequence Detector Using Sequential Circuits

A new phase-angle monitor is presented in this paper which can simultaneously measure the phase-angle between two signals and identify their lead-lag characteristics once every cycle. A novel phase-sequence detector is also described which can detect periodic and aperiodic sequence of pulses once in each cycle. Sequential logic circuit designs for these have been synthesized and tested in the laboratory. The inherent simplicity of these circuits particularly using digital integrated circuits and their adaptability in power system instrumentation and control are the novel features of the paper.