AN IMPROVED TECHNIQUE OF MEASUREMENT OF HIGH AC VOLTAGE

High a.c. voltage is generally measured by a potential transformer instead of an a.c. volt meter in order to avoid the hazards of high voltage. The conventional potential transformer is specially designed step down transformer where almost accurate voltage between primary and secondary is maintained to obtain output voltage directly proportional to input voltage. But this measurement suffers from ratio error and phase angle error, due to the effects of secondary current, magnetizing current and eddy current. In the present paper attempts have been made to reduce these currents by an improved design technique of the transformer. The technique has been utilized to fabricate a low voltage prototype unit. Its performance characteristics have been experimentally studied in a storage oscilloscope. The experimental results are reported in this paper. From these results a very good linear response with negligible phase angle error has been observed.