On the Measurement of Tooth-Ripple Losses in Laminated Poles

This paper presents the results of an experimental investigation into the problem of tooth-ripple losses in the laminated poles of rotating machines. The losses are measured by measuring the Poynting vector in the air-gap region of the machine between the surface of the poles and the slotted armature. Specially designed probes are used to measure the electric and magnetic fields and the signals from these probes are processed to give the required Poynting vector. This method also enables the direct measurement of the loss due to each individual harmonic under actual running conditions with all the harmonics simultaneously present. The experimental results are quite interesting in themselves and can also serve as a basis for comparing the various methods of calculating these losses. A comparison between the measured losses and those calculated on the basis of linear electromagnetic theory is also given.