Direct measurement of electric machine losses using the principle of the calorimetric method is described in this paper. The design and construction of a double chamber calorimeter (DCC) that can be used for measurement of harmonic losses of a 7.5 kW cage induction motor is discussed. The advantages of this approach are highlighted as compared with a single chamber type calorimeter. Conducted heat leakage through the calorimeter walls is estimated accurately by developing a simple thermal model and compared with the experimental results. Accuracy and reliability is investigated by performing experimental tests using a known heater. Limits for the air flow rate and temperature rise inside and across calorimeter chambers are derived, The calorimeter is capable of measuring a heat loss up to 1 kW corresponding to the 7.5 kW machine with an overall accuracy of /spl plusmn/15 W. This provides a high resolution required for measurement of motor harmonic losses caused by distorted waveforms.
