Motor Manual

General Motor Instructions


DANGER High voltage and rotating parts can cause serious or fatal injury. Safe installation, operation and maintenance must be performed by qualified personnel. Familiarization with, and adherence to, NEMA MG2, the National Electrical Code (NEC), and local codes is required. It is important to observe safety precautions to protect personnel from possible injury.

Personnel should be instructed to:

    1. Be familiar with the equipment and read all instructions thoroughly before installing or working on equipment.
    2. Avoid contact with energized circuits or rotating parts.
    3. Disconnect all power sources before initiating any maintenance or repair.
    4. Act with care in accordance with prescribed procedures in handling and lifting this equipment.
    5. Be sure unit is electrically grounded in accordance with code requirements.
    6. Be sure equipment is properly enclosed or protected to prevent access by children or other unauthorized personnel to prevent possible accidents.
    7. Be sure shaft key is fully captive before unit is energized
    8. Avoid contact with capacitors until safe discharge procedures have been completed
    9. Provide proper guarding for personnel against rotating parts and applications involving high inertia loads which can cause over speed
    10. Avoid extended exposure to equipment with high noise levels.

Inspection and Handling

Inspect unit to make sure no damage has occurred during shipment. Check nameplate for correct speed, horsepower, voltage, hertz and phase for conformance with power supply and equipment.
WARNING  Units should be lifted using all eyebolts or lugs if provided. These eyebolts or lugs are provided for lifting this unit only and must not be used to lift any additional weight. Lifting angle, from shank of eyebolt, must not exceed 30 degrees for machines with single and 45 degrees for machines with multiple lifting means. Replacement eyebolts must be per ASTM A489 or equivalent. All eyebolts must be securely tightened. Be careful not to touch overhead power lines with lifting equipment. Failure to observe this warning may result in serious personal injury.


Units should be stored indoors, in a clean, dry location & winding should be protected from excessive moisture absorption. NOTE: If motors are to be stored for over one year, refer to DLT Electric. If motors are to be stored for over one year and if gear and belt transmission units are to be stored for over six months, refer to DLT Electric.


WARNING  Use only UL Listed Hazardous Location Motors for service in Hazardous Locations as defined in Article 500 of the NEC. Units should be located in a clean, well-ventilated area. Units should be located in a suitable enclosure or protected to prevent access by children or other unauthorized personnel to prevent possible accidents.

Installation and Mounting

Mount unit on a firm, flat surface sufficiently rigid to prevent vibration. Drive belts and chains should be tensioned in accordance with supplier recommendations. Couplings should be properly aligned and balanced. For belt, chain and gear drive selection refer to the drive or equipment manufacturer.
For application of drive equipment refer to applicable information in NEMA MG1.
Motors have been dynamically balanced using a half key the same length as the full key shipped with the motor. If pulley length keyway is less than this length, rework long key by removing one-half of excess length between pulley and end of key to maintain balance.
Do not restrict motor ventilation. Unless otherwise specified on nameplate, motor is designed for operation in accordance with NEMA MG1 “Usual Service Conditions” which states an ambient temperature range of -15º C to 40º C (5º F to 104º F). Standard grease lubricated units are suitable for operation within this temperature range. Special lubricants may be required for ambient temperatures outside of this range. Note: Motors operating under rated load and allowable ambient conditions may feel hot when touched; this is normal and should not be cause for concern. When in doubt, measure frame surface temperature and confer with nearest office. Enclosed motors normally have condensation drain openings. Insure that drain openings are properly located and open (plugs removed) for the motor mounting position. Drain openings should be at lowest point of end brackets, frame housing and terminal housing when the motor is installed. This may require modification of motor to accomplish. If unit appears wet, and/or has been stored in a damp location, dry out thoroughly and check for adequate insulation resistance to ground before operating.

WARNING Guards should be provided for all exposed rotating parts to prevent possible personal injury. Keep fingers and foreign objects away from ventilation and other openings. Applications involving high inertia loads may damage this equipment due to motor over speed during coast shutdown. Such applications should be referred to DLT Electric.

CAUTION Do not force drive coupling or other equipment onto shaft, as bearing damage may result.

Power Supply and Connections

The power supply must agree with values on nameplate. Terminal voltage should not vary more than ±10% of nameplate voltage at rated frequency. Unbalanced line voltage, greater than one percent, can cause overheating. Do not exceed the rated load amperes on the nameplate. Starting controls and overload protection should be properly sized in accordance with the NEC and the control manufacturer’s recommendations.
Motor connections should be made by following instructions on connection diagram. Determine direction of rotation before connecting driven equipment. If direction of rotation label is supplied, operate only in specified direction. Rotation may be reversed on three phase motors by interchanging any two line connections. On single phase motors interchange leads per connection diagram on motor. Wiring of units, controls and grounding shall be in accordance with local and NEC requirements.

WARNING Failure to properly ground unit may cause serious injury to personnel. Where unexpected starting could be hazardous to personnel, do not use automatic reset starting devices.

Use of Variable Frequency Drives

TElectric motors can be detrimentally affected when applied with variable frequency drives (VFD’s). The non-sinusoidal waveforms of VFD’s have harmonic content which causes additional motor heating; and high voltage peaks.
Other effects of VFD’s on motor performance include reduced efficiency, increased load current, vibration and noise. Standard motors utilized with VFD’s must be limited to those application considerations defined in NEMA MG-1 Part 30. Refer to DLT Electric.

Oil Lubrication

Most oil lubricated units are shipped without oil. Refer to Instruction Manual with unit for specific type and grade of oil to be used, change interval and level. If lubrication instructions specify synthetic oil, do not substitute.

WARNING For applications in the food and drug industry (including animal food), consult the petroleum supplier for lubricants that are acceptable to the Food and Drug Administration and other governing bodies.


Inspect units at regular intervals. Keep units clean and ventilation openings clear of dust, dirt or other debris. Lubricate units per this operating instruction folder and instruction plate on unit. Excessive lubrication may damage the unit. Do not over grease.

WARNING Disconnect all power sources to the unit and discharge all parts which may retain an electrical charge before attempting any maintenance or repair. Screen and covers must be maintained in place when unit is in operation. Failure to observe this warning may result in personal injury.

WARNING U. L. Listed Motors for use in Hazardous Locations: Repair of these motors must be made by the manufacturer or manufacturer’s authorized service station approved to repair U. L. Listed Motors. The U. L. listing applies to the electric motor only and not the belt or gear transmissions or other devices that may be connected to the motor.