Explosion Proof Motors
|While many types of motors are built to be used in hazardous locations, a special type of motor called “Explosion Proof” is approved for Class I locations. Class I locations are those that have potentially explosive gases or vapors present on a regular basis. An explosion proof motor is built in such a way that it will contain an explosion within if one were to occur in the motor, and also to prevent the release of harmful gases or vapors into the immediate area that could be explosive as well.
Locations with potentially explosive gases/vapors include chemical plants, coal mines, petrochemical plants, fuel servicing areas (airplane hangars), utility gas plants, dry cleaning plants, companies with spray areas that have plastics or paint, etc. The motor must meet requirements of the Underwriters Laboratories (UL) and the National Electrical Code (NEC) for restrictions on class, group and temperature.
Understanding Motor Enclosure Types
Industrial motors are either open or totally enclosed. Motor enclosures are classified by the National Electrical Manufacturers Association (NEMA) and the International Electrotechnical Commission (European standard). Explosion proof motors are the “totally enclosed” type.
Know the difference. Open enclosure types include weather protected, splash proof, drip proof and guarded motors. These are not designed for use in hazardous locations, but are designed to allow ventilation of air around and over the motor’s windings. There are four types of totally enclosed motors as well. These are fan cooled TEFC, air over TEAO, non-ventilated TENV, and explosion proof.
Motor use for various applications is determined using three classifications, which are Class I (gases, vapors, liquids); Class II (dusts); and Class III (fibers).
Explosion Proof Motor Construction
These motors must have a robust construction, generally with Class F insulation, fan covers, cast iron end plates, and stainless steel breathers and drains. Other features may include armatures with polyester varnish that can withstand high temperatures, oversized conduit/connection boxes, low loss steel lamination, and vibration reduction due to dynamic balancing. Explosion proof motors must also be constructed to resist corrosion, to limit extreme temperatures, and to prevent the ignition of explosive gases/vapors in the work area. These are flametight with narrow tolerances for the joints and flanges, which causes hot gases from an internal explosion to cool quickly so the gases cannot be ignited.
If your company is in need of this type of industrial motor, read more or ask about explosion proof motor classifications and ratings to ensure you’re getting the right motor for your application. Carotron resells several explosion proof dc motors and ac motors, manufactured by Leeson, Baldor and Marathon Electric.
CALL CAROTRON, We Can Help! Contact a customer representative or engineer at Carotron, Inc. at 1-888-286-8614, and let us review your application and offer the right components to do the job.