Thermal Network Calibration Using Short-Transient and Steady-State Thermal Tests

This paper describes the process of calibration of a full-scale steady-state thermal network of a 4 kW induction motor. The pre cursor to this calibration process is the winding thermal test of the motor; where the series connected three phase winding is supplied with de voltage. A short-transient test as well as a steady-state test have been performed. The main heat-flow path is from winding to the stator core then onto to the motor housing. By adjusting the thermal parameters along this path, a good agreement between the temperatures predicted by the analytical thermal circuit and the measured winding and frame temperatures can be found. This process of calibration allows reliable estimation of effective winding thermal conductivity, and contact resistances in the stator side of the motor, which are usually difficult to determine solely through analytical means.