Online surge testing applied to an induction machine with emulated insulation breakdown

A breakdown of the electrical insulation system can cause catastrophic failure of the electrical machine and bring large process downtime losses. Preventive maintenance and online monitoring are some of the methods to improve reliability and reduce unscheduled downtime. One of the main reasons for the failure is the breakdown of the stator insulation. The offline surge test is the most commonly used offline test to assess the condition of the turn insulation. There is no online monitoring method that is applicable to low voltage machines and has the same capabilities as the surge test. This paper shows how to conduct a surge test online. The required hardware and the test procedures are described. A new test setup that emulates the arcing due to a weak turn insulation is used to validate the technique proposed.