Precision calorimetry for loss evaluation

Stray load losses have always been difficult to determine with precision so it has been difficult to refine methods of their prediction. Some national standards still allow stray loss to be included as a fixed percentage figure of input power. Alternative standard methods of testing induction machines determine total losses indirectly by measuring input and output powers and fitting a "loss model" to the resulting data. An objective of this work is to examine the validity of such an approach. Calorimeters may be used to measure motor losses directly in loaded induction machines. This technique overcomes the potential inaccuracies of input output methods, due to the subtraction of two similar magnitude power measurements. However, the technique is not without its experimental problems and these need to be addressed in order to obtain reliable results over a long time period