Matthew Conville, MBA, PE
EASA Technical Support Specialist
In today’s global economy, it is quite possible to get electric motors from all over the world. This gives us plenty of options to choose from when selecting an electric motor. Most electric motors that are 500 hp (373 kW) or less will conform to one of two basic manufacturing standards; NEMA or IEC. Both have specific clauses which define the voltage stress limits an induction machine can be subjected to in its application, which is powered by Variable Frequency Drives (VFDs)/converters. The intent of this article is to focus on IEC standards for managing voltage stress in VFD applications as it pertains to the motor’s windings. If more detail is needed on NEMA applications, please refer to NEMA MG-1 Part 31.
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Voltage stress: Not as simple as it sounds
Saturday, August 4, 2007Have you ever wondered how a lightning rod works? That small rod atop a large building extends less than a yard (meter) above the building. Yet the lightning is attracted to that sacrificial rod rather than to the building. If you have not wondered about lightning rods, Iʼll bet you are curious about what lightning rods could possibly have to do with electric motors. The common denominator between electrical windings and lightning rods is geometry.
EASA Technical Manual
More information on this topic can be found in EASA's Technical Manual- Section 2: AC Machines
- Section 5: Electronics
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