Evaluation the Effects of Overload and Ambient Temperaturein Power Transformer in M.R.E.C

This paper presents the evaluation of power transformers overloading in transmission and over distribution substations, supervised by MAZANDARAN which is a regional electrical company in Iran. It was found that ambient temperature rise and overload are two important factors in performance of these substations. Rise in electric power consumption increased the power transformer loads by %16.3 during year 2006 in provinces of MAZANDARN