Measurement of surface losses in solid poles of synchronous machines under load conditions

In designing solid-pole synchronous machines, it is important to take into account the surface eddy-current losses in the pole shoes. For large-scale machine design, it is especially important to estimate the surface losses under load conditions because only measurement under no-load conditions can be conducted before shipping. Shima et al. have computed that the surface losses under no-load and load conditions of a solid salient-pole synchronous machine by using finite element analysis (FEA). It has been found that the losses under the rated loads are much larger than those under the no loads despite the same armature voltage. In this paper, a method to measure the surface losses under load conditions is proposed and conducted in order to verify the above FEA results.