A Study of Stray Load Losses in Core Clamp Plates of Salient Pole Synchronous Machines

Abstract

The importance of stray loss evaluation in machines is discussed, end the literature on clamp plate loss in particular is extensively reviewed. The design of two models having their core lengths in the ratio 3 : 1 is presented, end from tests on the models, the loss in clamp plates of various materials is evaluated sat various excitation currents and power frequencies, The flux densities at the clamp plate surfaces pre extensively examined using Hall probes. Hell probe: instrumentation end date handling by computer, is presented, the clamp plate surface flux densities ere obtained with both a.c. and d.c. excitation. The waveforms of the surface flux densities are presented in detail, end indicate the complex nature of the problem. The use of the Hell probe equipment on actual machines in industry is illustrated, and further evidence of the intricate nature of the end-field problem is given, The flux density end loss investigations on the models show that even with e moderate degree of saturation in the laminated cores, the end region flux density patterns are materially affected, The clamp plate loss can then be considered as having two components, one due to winding overhang m.m.f., end the other due to flux passing from core to clamp plate at the interface, Within the limitation of the method used, a technique is presented for evaluating clamp plate losses in machines from the test results obtained on the models.