Experimental investigations of high-voltage motor switching surges

The paper presents the results of experimental investigations of surges appearing on the insulation of high-voltage (HV) motors for normal switching operations and during an interrupt of aborted start. High-voltage motors were switched by oil-minimum circuit breakers, air magnetic and vacuum switching devices. Investigations were performed mostly on 6 kV isolated neutral station service cable networks of thermal power plants, industrial or similar installations. On the basis of the results, certain measures are proposed for limiting transients, thereby increasing the reliability of HV motor operation.