Investigation on surge testing for winding insulation fault detection in an online environment

A breakdown of the electrical insulation system causes catastrophic failure of the electrical machine and brings 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 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 investigates the applicability of the surge test in an online environment and shows possibilities and limitations of the online test. The investigtion is verified by experimental results.