Investigation of Tangential Lines and Prospective Values for TRV Measurements

SUMMARY The prospective transient recovery voltage (TRV) at current interruption for circuit breakers should be measured by using an ideal circuit breaker. Prospective values of the TRV are obtained by drawing the tangential line to the TRV waveform. But, it is difficult to draw the tangential line on the 4-parameter TRV waveform automatically by computer software. This paper presents a new method of drawing the tangential line on the 4-parameter TRV waveform. It is easy to draw the tangential line on the TRV waveform by a simple waveform transform process. This method is easy to code as computer software. We also investigate the method of deciding the current zero in prospective TRV measurements.