DC resistance of transformer is one testing item which must be tested during ex-work test of semi-finished products and final products, installation, acceptance test and preventive test of electric power department, which can effectively find out material selection of transformer coil, welding, looseness of connection part, missing strand, broken wire etc manufacturing defect and existing hidden problems after operation. The traditional high and low voltage series connection test of the constant current source can’t be applied during temperature rise test of the power transmission transformer because difference between high and low voltage windings of the transformer is great. Now if two testing meters are applied for testing, it is liable to damage the instrument because of mutual induction between high and low voltage windings of the transformer.
Kingrun Instrument Company Ltd has developed and researched JYR 20W temperature rise tester (Heat-run tester) , which solves this problem. The instrument applies double constant current source design, CUP program controlled charging and discharging sequence and perfect protection measures, which is highly applicable to temperature rise test of the transformer with great difference between high and low voltage windings.