The equivalent circuit constants of three-phase induction motor （IM） are used for the performance calculation and the operation of variable speed control. So，it is very important to accurately identify the equivalent circuit constants. In this paper，a simple identification method of equivalent circuit constants for IM using the difference amount of actual load test data is proposed. In proposed method，no load test，mechanical loss measurement test and restraint test are no need. To identify the equivalent circuit constants，the actual load tests of two different slips （for example，load factor of 75% and 60%） are carried out. And the primary resistance measurement by the DC voltage drop method is also carried out. The circuit analysis based on the difference amount derives the relational expression between resistance and reactance in the secondary side circuit. Under the range of slip is from 1% to 6%，the calculation values by the proposed method are the good agreement with the measured value.

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