Other Motors Topics
Motor Enclosures
 Figure 17 - Washdown duty motors include white dc motor (left), three-phase motor (right), single-phase motor (top) and the stainless steel motor in the foreground.
|
Explosion-proof machines — Hazardous atmospheres require special totally
enclosed motors. Motors for these atmospheres are designed to standards established by
Underwriters Laboratories (UL). Only after a motor has been examined and approved by UL
can it be sold as an explosion- proof motor.
Washdown — For those applications that are subjected to washdowns
with high-pressure liquid cleaners require more features to protect the motor from severe
conditions. These are typically encountered in such industries as food processing plants
and dairies. The motors are housed in a steel enclosure that is covered with an FDA approved
epoxy paint or in a stainless-steel enclosure.
Seals at every opening are selected to prevent fluids from entering the motor as
well as out of the bearings. Inside, all parts are covered with epoxy paint or other
material to retard corrosion, Figure 17.
Bakery service — For the baking industry,
motors similar to the white washdown motors are rated for service according to
Baking Industry Sanitation Standards Committee (BISSC) requirements.
Every bend is filleted to prevent material build-up in a sharp bend, fold, or crack.
Typically the same internal and external protection is provided as is supplied with
washdown motors, and the final finish is a glossy, smooth white.
Frameless motors — Frequently designed into machine tools to power high-speed
spindles, frameless ac motors are now finding acceptance in other machines that
have space constraints or unusual mounting requirements.
Recent technological advancements — new cooling techniques, more precise feedback
devices, and expanding use of CAD — are extending the popularity of frameless motors
into more registration-oriented operations such as paper converting and printing.
Construction of frameless ac motors, electrically, is no different than
conventional permanent-magnet and induction motors. The frameless designs can be
controlled by the same drives as those used to control frametype motors.
|
