Calorimetric system for measurement of synchronous machine losses

An open-cycle air-cooled calorimetric system for the measurement of power losses of a 150-kVA synchronous generator is described. The enthalpy increase and mass flow of the cooling air are determined by measuring the temperature rise, relative humidity, absolute pressure and the pressure drop over a known aerodynamic resistance. The loss measurements are performed using the balance method by calibrating the system against a set of heating resistors. In addition, the difference in heat leakage between the balance test and actual test run is determined by measuring two additional calibration curves. The losses of the test machine are measured in three different loading points. From the error analysis, measurement errors of 5.0 and 1.9% are obtained for the total electromagnetic loss at no load and in rated-load operation, respectively.