Stator Winding Insulation System Per Iec 60079-7, What, Why, How, Pros and Cons.

Standard IEC 60079-7 [1] describes Type of Protection increased safety “e”. For Level of Protection “eb” machines for use in Zone 1 or Class I, Division 1 hazardous locations, if the rated voltage exceeds 1 kV, a stator winding insulation type test is required. For Level of Protection “ec” machines for use in Zone 2 or Division 2 hazardous locations, the requirement for type tests differs based on the equipment group, rated voltage, and the type of the winding. This paper will discuss in depth the winding insulation system for the synchronous and asynchronous motors including insulation system materials and process differences needed to meet the test requirements. The paper will cover the test procedures, requirement for test samples, details for performing the test and evaluating the test results. It discusses further advantages and disadvantages of the test, passing the tests, and the long-term reliability of the winding insulation system. The impact of failures occurring in service with respect to rebuild/rewinding if required, ensuring or validating duplicate winding by a repair shop if not rebuilt at the OEM. The paper has input from OEMs, testing facilities, certifiers, and end users.