The National Electrical Manufacturers Association (NEMA) published the standard MG 1-2009 Motors and Generators. MG 1 is intended to be a definitive standard for practical information concerning performance, safety, testing, construction, and manufacture of alternating current and direct current motors and generators. The standard, which was last revised in 2007, is produced by NEMA’s Motor and Generator Section.
MG 1 has been updated to include the latest in international motor efficiency requirements; the section revised the motor efficiency tables for 50 Hz products to reflect those of IEC IE Code as per IEC 60034-30. Other significant changes include revised minimum insulation resistance; clarification of motor efficiency values; and the addition of sections on auxiliary devices, ratings tests, and performance for ac and dc motors.
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