Calorimeter Measurement of Stray-Load Losses of a 55,000-Kva. Generator Having Enclosed System of Ventilation

The paper covers a number of thermal or calorimeter tests which were made on a 55,000-kva. generator at the Queenston generating station of the Hydro-Electric Power Commission of Ontario. The objects of the tests were to determine stray-load losses on short circuit and under rated load, and to obtain some information regarding the accuracy of this type of test. The paper includes descriptions of the methods followed and of the actual tests made. The details of the calculations are given in the appendix. The results of the tests show that the stray-load losses can be determined with fair accuracy by this method on large units when an enclosed system of ventilation is used. They also seem to show that the difference between the stray-load losses under load conditions and under short-circuit conditions is slight, and that a test under load conditions is justified only when a very accurate determination of the losses is required. For most purposes, a test under short-circuit conditions seems to be sufficient.