engleski

An improvement of electrical motor insulation condition testing

This paper presents one of the maintenance test methods and the results of its application in the determination of the insulation condition of high-voltage electric motors. Testing and data processing were carried out on site using a PC and adequate software. Automatization eases and speeds the testing and the interpretation of results. This method is a modification of the Höfler method. Highly stabilized dc voltage is applied to the motor windings in 5 steps, from 0.3 Un to 1.5 Un, in steps of 0.3 Un, while at the same time the leakage currents are being measured. In the case of "ideal insulation", leakage currents are proportional to the applied dc voltage, i.e. the insulation resistance is independent of the applied voltage. In reality, insulation resistance and leakage currents depend on the applied voltage. The ways the leakage current depends on voltage and its magnitude can be used to determine the insulation condition. The insulation condition is estimated based on the non-linearity coefficient’s value.

electrical motor; insulation; condition testing

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