ALSET ELECTRIC Ltd.

MOTOR REWINDING & SERVICING

Terminology Guide

The following selection guide is designed to help you determine the correct motor for your application. It is written in general terms and is intended only as an aid. The customer is solely responsible for the motor performance and suitability in applications for their use. No application fitness approval is implied as that can only be determined by the customer.

Our commitment to quality will consistently meet the requirements of our customers every time.


BEARINGS

Motors come with either sleeve bearings, ball bearings, or roller bearings. Sleeve bearings are more economical and quieter than ball. Ball bearings carry heavier loads and can withstand more severe applications. Roller bearings are used in large motors for belted loads. Belting data must be provided on all belted applications. Standard horizontal motors can be mounted in a vertical shaft down orientation (brakemotors exempt) .

MAXIMUM SAFE MECHANICAL SPEEDS

Direct-Coupled Direct-Coupled
Motor Frame RPM 3600 RPM 1800,1200,900
56-184 7200 5400
213-256 5400 4200
284-286 5400 3600
324-326 4500 3600
364-365 4500 2700
404-449 3600 2700

 

Note: TEFC motors are limited to 4000 rpm.

 

Operation above 60Hz will increase motor noise, vibration, and reduce bearing life. Do NOT exceed 100 degree C bearing hub temperature.

For belted loads do not exceed 60Hz speed by more than 25%. NEMA TS shafts are not suitable for belted loads.

 

ELECTRICAL TYPE/STARTING METHOD

Motors are either capacitor start, split phase, permanent split capacitor, or three phase. Capacitor start motors have high starting torque, high breakdown torque, and relatively low starting current. Split phase motors have medium starting torque and medium starting current. Permanent split capacitor motors have low starting torque and low starting current. Three phase motors have high starting torque, extra high breakdown torque, and typically very low starting current.

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ENCLOSURE

Motors are available in dripproof, totally enclosed, and explosion proof enclosures.

Dripproof motors have open enclosures and are suitable for indoor use and in relatively clean atmospheres. Dripproof motors have ventilating openings constructed so that drops of liquid or solid particles falling on the machine at an angle of not greater than 15 degrees from the vertical cannot enter the machine.

Totally enclosed motors are suitable for use in humid environments or dusty, contaminated atmospheres. Totally enclosed non-ventilated motors are NOT cooled by external means. Totally enclosed fan cooled motors are cooled by external means that are part of the motor but not in the internal workings of the motor. Totally enclosed air over motors are totally enclosed non-ventilated motors that need to be sufficiently cooled by external means, provided by the customer.

FREQUENCY/HERTZ

The number of complete alternations per second of an alternating current. Expressed in Hertz as 60 Hz, 50 Hz, or 60/50 Hz.

HORSEPOWER

Motors are available from 1/12 to 600 horsepower.

MOUNTING

There are several mounting configurations available: Rigid base or resilient base for belted drive applications (the resilient base also minimizes vibration and noise) , C-Face, D-flange, P-Base, thru-bolt, resilient ring (only) , and belly band mount are for direct drive applications.

NEMA DESIGN CODES - THREE PHASE

Design
Letter
Starting
Torque
Breakdown
Torque
Starting
Current
Slip at
Rated
Load
A Normal High High Low
B Normal Medium Normal Low
C High Normal Low Low
D Very
High
N/A Low High

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Single Phase NEMA SERVICE FACTOR @ RPM LISTED

HP 3600 1800 1200 900
1/12 1.4 1.4 1.4 1.4
1/8 1.4 1.4 1.4 1.4
1/6 1.35 1.35 1.35 1.35
1/4 1.35 1.35 1.35 1.35
1/3 1.35 1.35 1.35 1.35
1/2 1.25 1.25 1.25 1.15
3/4 1.25 1.25 1.15 1.15
1 1.25 1.15 1.15 1.15
1.5 & Up 1.15 1.15 1.15 1.15

 

PHASE/POWER SUPPLY

Is the power supply three phase or single phase? Most home and farm applications require single phase motors, while most factories and large commercial and industrial users require three phase motors. Single phase motors can be used on three phase systems. Three phase motors, however, cannot be operated from single phase systems. Motor damage may result.

SPEED/RPM

3600, 1800, and 1200 are the most common 60 Hz synchronous speeds with the full load speed equivalents of 3450, 1725, and 1150.

VOLTAGE

Standard voltages are 115V, 115/230V, 230V, 230/460V, 460V, and 575V at 60 Hertz. Many of our ratings are 115/208-230V or 208-230/460V at 60 Hertz. Dual voltage motors are easily reconnected from information shown on the nameplate of the motor. Motors rated at 230 volts will operate on a 208 volt network for most applications that have nominal starting torque requirements. Starting torque and peak running torque at 208 volts will be 20-25% less than at the 230 volt level.

If the starting torque is more than nominal, the next higher horsepower 230 volt motor should be used. Motors nameplated 115/208-230 or 208-230/460 volts will operate successfully at 208 volts. At 208 volts, the motors may not meet NEMA specifications.

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