Siły elektromagnetyczne działające na kliny magnetyczne zamykające żłobki stojana

In sustained use of high-voltage electric motors, when magnetic wedges are used to close the slots, loosening and slipping out of the wedges can be observed. This can lead to destruction of the motor as a result of seizure of the rotor and deformations of stator windings caused by dynamic action of current in absence of rigid closing of slots. In the course of inspection of dismounted wedges, one can observe evident losses of wedge material, in the pack part, as well as absence of wedges in some of radial ventilation channels. This is an effect of forces acting on magnetic material in electromagnetic field. The analysis of forces acting on the magnetic wedge was conducted by means of a model being a representation of a fragment of the motor's circuit. As a subject of analysis, the area being a cross section in plane transversal to motor's axis and covering stator slot and rotor slot together with neighboring teeth has been adopted. The performed calculations proved that in the model, relative position of slots with respects to each other results in changes of both value and direction of the resulting force reduced to the geometric centre of the wedge.