5.5.Inspection and Test of On-load

5.5.Inspection and Test of On-load Voltage-regulating Changing Apparatus: when the transformer has no voltage, as for the on-load tap changer, its manual operation should be no less than 2 cycles and motor-driven operation should be no less than 5 cycles. Upon the motor-driven operation, the supply voltage should be over 85% of the rated voltage. There shouldn’t be any jam for the operation and the interlock procedure and electrical and mechanical limits should be normal. After the circulating operation, conduct the measurement of the DC resistance and voltage ratio of the winding with the bushing under all branch connection.