Insulation resistance precheck unit of low voltage circuit breaker based on piezoelectric ceramic transformer

The main line insulation predetection unit embedded in the low voltage circuit breaker was designed aiming at the prevention of accidents, which take place in the closing operation in low voltage power supply system. The overall structure was introduced. Piezoelectric ceramic transformer high voltage generating circuit and Insulation resistance detection circuit were demonstrated in details. The results of the experiments show that the unit is effective and the measurement reference error is less than 5%, it is suitable for prechecking the main line insulation state of the load side before the low voltage circuit breaker closing.