Flashover characteristics of transformer condenser bushings

TERMINAL bushings for high-voltage power transformers require many electrical tests to demonstrate their fitness for service. A vital part of the complete transformer, they operate under extreme variations of temperature and weather conditions. They are subject to all the variations in load, ambient temperature, and surges that the transformer windings receive, and in addition must be built to withstand severe attacks of ice and snow, rain and hail, hot sun, smoke, fog, dust, and dirt. They must be stronger against flashover than the protective apparatus, and must maintain their strength year in and year out. The terminal bushing is a part of the transformer and not an individual piece of apparatus; under normal service conditions it should be proportioned in strength to the winding, and should be co-ordinated with the winding under impulse voltage conditions.