Specification Sheet

2−10 Installation & Operation MN408
If applied in a Division 1 or 2 / Zone 1 or 2 and Zone 21 or 22 environment, this excessive temperature
may cause ignition of hazardous materials. Operating the motor at any of the following conditions can
cause the marked surface temperature to be exceeded.
1. Motor load exceeding service factor nameplate value
2. Ambient temperature above nameplate value
3. Voltage (at each operating frequency) above or below rated nameplate value
4. Unbalanced voltages
5. Loss of proper ventilation
6. Operation outside of the nameplate speed / frequency range
7. Altitudes above 3300 feet / 1000 meters
8. Single phase operation of polyphase equipment
9. Unstable current wave forms
10. Lower than name plate minimum carrier frequency
Thermal Limiting
Thermal limiting devices are temperature sensing control components installed inside the motor to limit
the internal temperature of the motor frame by interrupting the circuit of the holding coil of the magnetic
switch or contactor. They are required for most Division 1 and Zone 1 applications. For Division 2 or
Zone 2 applications, motors should be selected that preclude running temperatures from exceeding the
ignition temperatures for the designated hazardous material. In Division 2 or Zone 2 classified locations,
thermal limiting devices should only be used for winding protection and not considered for limiting all
internal motor temperatures to specific ignition temperatures.
Equipotential Bonding and Shaft Current Reduction
Larger motors (ie WP construction) may require proper bonding between motor enclosures and covers to
avoid the risk of stray currents during start up. Fastening methods and bonding straps must not be modified.
Bearing currents can exist in some motors for both line−fed and inverter−fed applications. Larger line−fed
motors may require at least one insulated bearing to prevent a flow of current through the bearings. Do not
defeat such insulation whether the motor is line−fed or inverter−fed applications. Inverter−fed motors may
require additional bearing insulation or even a shaft brush. Do not defeat such features. When the motor and
the coupled load are not on a common conductive baseplate, it may also be necessary to electrically bond
together the stationary parts of the motor and the coupled equipment.
Repair of Motors used in Hazardous Locations
Repair of hazardous certified motors requires additional information, skill, and care. It is the customer’s
responsibility to select service shops with proper qualifications to repair hazardous location motors.
Contact the manufacture for additional repair details. Use only original manufacturer’s parts.
Repair of Explosion Proof or Flame Proof Motors Class I Division 1 and Zone 1
In the North American market, recertification programs are offered by Underwriters Laboratories and
Canadian Standards Association which allow authorized service shops to mark the rebuilt motors as
certified. In the international markets using IEC based requirements, repair should be undertaken only
after consulting IEC60079−19 Explosive Atmospheres−Part 19 Equipment repair, overhaul and
reclamation. If use of a certified repair facility is desired, consult the IECEX Repair Scheme at
http://www.iecex.com/service_facilities.htm
Explosion proof and flameproof motors achieve their safety based on the mechanical construction −
flameproof joints and bearing clearance, and the electrical design including any thermal limiting devices. If
it is necessary to repair a flameproof or explosion proof motor, it is critical that the mechanical flameproof
joints be maintained. Consult Baldor Electric Company for flameproof joint construction details. Use only
BaldorSReliance supplied parts. Baldor does not recommend reclamation of parts. Since this protection
method also relies on temperature being maintained, make sure that any rewinding uses the original
electrical designs, including any thermal protection that may be present.
Repair of Dust Ignition Proof Motors − Class II Division 1 and 2, Zone 21 and 22.
For Dust Ignition Proof, proper sealing is required. Do not modify the motor construction to add any
additional opening, and ensure that proper sealing is maintained in the connection box and at the shaft
seal. Since this protection method also relies on temperature being maintained, make sure that any
rewinding uses the original electrical designs, including any thermal protection that may be present
Repair of Class I Division 2 and Zone 2 motors
For Division 2 and Zone 2, the internal and external temperatures are of concern. Since this protection
method also relies on temperature being maintained, make sure that any rewinding uses the original
electrical designs, including any thermal protection that may be present. Use only Baldor replacement
thermostats, if provided.