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. 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 on 460-V/230-V rated induction machines that are connected in the low-voltage configuration. The required hardware, test procedures, and evaluation of the results are described. Instead of using a bolted short to emulate the insulation breakdown, a new approach is used for the experimental validation. The arcing is emulated either by using an insulation sample that breaks down at a certain test voltage or by using a circuit that emulates the breakdown.