Selected diagnostic methods of electrical machines operating in industrial conditions

The article proposes a series of tests on the groundwall insulation, utilizing the dc voltage and consisting of three related procedures. After running the tests, the obtained data are analyzed and insulation is graded in accordance with proposed criteria. These criteria are presented in the paper. The method has been illustrated by real-life example of electrical machine tests´ results. The article describes the turn-to-turn insulation substitute circuit and results of simulations and measurements. There is shown a new diagnostic method to determinate condition of this insulation. The suggested method can be used in any kind of machine and it is easy to use. The most commonly damaged machine parts, except the insulation, are bearings, so the authors decided to mention in the article, about vibration measurements.