Phase sequence test indicator - includes bridge with optical indicators and controls tone signal for audio monitoring

摘要

The phase sequence test instrument is for three phase circuits, and has bridge circuit with phase-shifting arms, one or two electro -optical indicators, and a tone generator, which is inoperative with the right phase sequence, but which is controlled by the electro-optical indicators through opto- electronic converters to give an audible signal on wrong connection. The circuit may be arranged to give tones of different frequency corresponding to different fault conditions, e.g. right or left handed phase rotation. Audible signals enable to operator to concentrate on arranging connections and to concentrate on this without having to observe an optical indicator at the same time.