Gradient temperature on 3Phase transformer core with staggered yoke with 90 T-joint

Abstract

This paper describes the result of measurement of localised temperature rise on 100kVA 3phase distribution transformer assembled with 90o T-joint and mitred lap corner joint with stagger yoke with overlap length of 10mm. The measurement involves the initial temperature and last temperature after 20 minutes experiment. The temperature rises have been measured using no load test by arrays of thermistor on M5 (CGO) grades material of transformer core laminations. The localised temperature rise at the outer 90o T-joint is 0.075 oC/minutes and rises to be 0.095 oC/minutes at the inner 90o T-joint when the transformer core energized 1.5 T 50Hz. A small amount of flux deviation from the rolling direction occurs at the overlap.