Motor standards: Activities at UL, NEMA; can you help

UL is undergoing a major revision of their motor standard UL1004, while National Electrical Manufacturers Association (NEMA) is seeking help with another motor standard.
By Control Engineering Staff November 29, 2007

UL

is undergoing a major revision of their motor standard UL1004, while

National Electrical Manufacturers Association (NEMA)

is seeking help with another motor standard.

The new principal designated engineer at UL headquarters in Northbrook, IL, has developed a general specification, UL 1004-1 that identifies those common parts and structures shared by all motors and generators and describes the necessary spacings and clearances to guarantee safe operation. He has established an alternate approach to gain acceptance through functional testing without resorting to arbitrarily large clearances. UL1004-1, -2, -3, -4, and -5 are in the process of final review before going to the standards technical panel for an acceptance vote. The five standards are:

* UL 1004-1—Rotating Electrical Machines,
* UL 1004-2—Impedance Protected Motors,
* UL 1004-3—Thermally Protected Motors,
* UL 1004-4—Electric Generators,
* UL 1004-5—Fire Pump Motors.

UL is now beginning the creation of new standards UL 1004-6 through -9 covering inverter driven motors, step and servo motors, brushless dc motors and refurbished motors.

UL is playing an ever increasing role in recognizing and listing electric motors and their associated drives in a wide range of appliance, medical, office and factory machines for the purposes of acceptable safety levels in order for suppliers and users to obtain insurance coverage.

NEMA has the role of technical action group (TAG) for electric motors, drives and controls used in US Industry. They are responsible to ANSI (American National Standards Institute) for standards about motors and drives that specify sizes, mountings, general performance, etc. NEMA MG1 is the definitive for large induction motors (1 HP to 500 HP).

A second NEMA group, the industrial controls section (ICS) provides basic standards for controls and drives and control motors. ICS 16 is a control motors and feedback devices standards last updated in 2002. Any standard automatically becomes available for review every 5 years. The NEMA 17, 23 and 34 frame sizes are described and controlled in this standard. Brush dc motors, brushless PM motors and step motors along with optical encoders and resolvers are covered in ICS16. Technology has moved on, and this standard is in need of update.

Greg Winchester at NEMA is manager of this group. He needs help in updating this standard. For example, at least 3 more frame sizes need to be added to the ICS16 standard. They are Sizes 8, 11 and 14/15. This is a call to you to have one of your engineers involved in reshaping this standard.

Dan Jones

Incremotion Associates

,

Motion Control Association

sitting on the UL and NEMA panels discussed.

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