Experience in Short Circuit Testing of LV Short Circuit Testing Transformer

For an On-line Short Circuit Facility, the main component of the facility is the Short Circuit Testing Transformer. There are no regular manufacturers of such transformers. Design of such transformers needs to be done taking into account many factors. The role of the manufacturer in getting the transformer designed for a particular application is very critical. Detailed checking the design calculations for various parameters including adequate design margins for heavy electromagnetic forces during short circuit, before commencement of manufacturing is very important. Such transformers are usually low impedance transformers and short circuit testing of such transformers to verify the design poses several problems, since the full-scale short circuit test means abnormally high electromagnetic forces, and may reduce the life of test transformer. It is debatable whether full-scale short circuit testing is necessary. Recently a Low Voltage short circuit test station was set up at Bangalore for an US multinational. Brief design features of the Test transformer and short circuit testing of the LV Short Circuit Transformer, decisions taken regarding full scale applicability of Short Circuit Tests with reasons thereof are enumerated in this paper.