Calculation research of economical operation parameters of three-winding transformer

Based on the general expressions of the three-winding transformer total loss,this paper draws-in the concept of equivalent load loss of the three-winding transformer to enable the three-winding transformer total loss to have the same expressions as two winding transformers,furthermore to derive the calculation formula of economic load power,economic load rate,efficiency of economic operations of the three-winding transformer.It explains the practice usage of the formula above-mentioned with a capacity ratio 100/100/50 of 110kV three-winding transformer as a practice calculation example.