RS Electric Motors - Motor Sales & Service 800-279-2267
Home About Us Motors Accessories Services Terminology Site Map Contact Us Apply
General Purpose Three Phase Motors
General Purpose Single Phase Motors
Explosion Proof Motors
Definite Purpose Motors
Agriculture/Farm Duty Motors
Brake Motors
Pump Motors

  Search all Brands
  Enter Catalog/Model#:
     
Ag Duty Specials!
Compressor Duty Motors
Vertical Pump Motors
Medium Voltage Motors
Used or Rebuilt, AC or DC Motor Inventory!
PdMA - EMax Online Dynamic Testing

EASA

 

 

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. If further assistance is required in selecting the proper motor, please contact R/S Electric Motors Service.

AGENCIES:

U.L. (Underwriters Laboratory) and CSA (Canadian Standards Association)
Where applicable, our motors including Inverter Duty, have UL listing for explosion proof enclosures, UL recognized construction for non-explosion proof enclosures, and UL recognition as a motor/protector combination. Our motors are also CSA certified for both explosion proof and non-explosion proof enclosures.

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).

BLUE MAX¨ AND BLACK MAX¨ INVERTER DUTY RATED MOTOR
APPLICATION INFORMATION AND RESTRICTIONS:

General Information:
Variable torque ratings are suitable for operation from 0 to base speed. Variable torque operation beyond base speed must be reviewed by your application specialist.

BLUE MAX¨ and BLACK MAX¨ constant torque motors provide full rated torque within their listed speed range, without exceeding their Class F temperature rating on inverter power. Ratings in this catalog are based on extensive testing with IGBT inverters, set at a minimum 3 KHz carrier frequency, and are designed for operation at 150% of rated torque for one minute, up to the base speed of the motor (overload capacity declines to 100% as the motor reaches maximum speed). These motors accommodate Constant Horsepower (CHP) operation to 1-1/2 to 2 times base speed, subject to the motor's maximum safe mechanical speed limit.

It is the responsibility of the startup personnel during commissioning of the VFD/motor combination to properly tune the drive to the motor for the specific application. The correct voltage boost and volts/Hz settings are application dependent and unique to each motor. Procedures for these adjustments should be in your VFD user manual. WARNING: Power factor correction capacitors should NEVER be installed between the drive and the motor.

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.

GUIDELINES FOR APPLICATION OF GENERAL PURPOSE THREE PHASE MOTORS ON VARIABLE FREQUENCY DRIVES:
General purpose three phase motors, operated on IGBT inverter at 3KHz carrier frequency, are suitable for operation on variable frequency drives per the following table. (X = Suitable)
Enclosure Eff. Frame Variable Torque 2:1 Constant Torque 10:1
Constant
Torque
Maximum Cable Length(ft) @3KHz Carrier Frequency
230
Volt
Maximum Cable Length(ft) @3KHz Carrier Frequency
460
Volt
Maximum Cable Length(ft) @3KHz Carrier Frequency
575
Volt
Dripproof All 56-326T X     600 125 40
Dripproof All 364T-500U X     1000 225 60
TEFC Std 56-326T X X   600 125 40
TEFC Std 364T-449T X X   1000 225 60
TEFC Series E 143T-256T X X X 600 125 40
TEFC Series E 284T-326T X X   600 125 40
TEFC Series E 364T-445T X X   1000 225 60
TEFC XRI 143T-145T X X X 600 125 40
TEFC XRI 182T-256T X X X 1000 225 60
TEFC XRI 284T-449T* X X   1000 225 60
*Except 400HP
NOTE: Higher carrier frequency limits allowable cable length.

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.

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.

Explosion proof motors are also totally enclosed fan cooled or non-ventilated, but designed for applications in hazardous atmospheres which contain explosive gases or dusts. Here is a brief description of the hazardous locations of both gaseous and dusty atmospheres as classified by the National Fire Protection Association's National Electrical Code and printed from the handbook.
  • Class I, Group A - Atmospheres containing acetylene.
  • Class I, Group B - Atmospheres containing hydrogen, fuel, and combustible process gases containing more than 30 percent hydrogen by volume, or gases or vapors of equivalent hazards such as butadiene, ethylene oxide, propylene oxide, and acrolein.
  • Class I, Group C - Atmospheres containing ethyl ether, ethylene, or gases or vapors of equivalent hazard.
  • Class I, Group D - Atmospheres such as acetone, ammonia, benzene, butane, cyclopropane, ethanol, gasoline, hexane, methane, natural gas, naphtha, propane, or gases or vapors of equivalent hazard.
  • Class II, Group E - Atmospheres containing combustible metal dusts including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment.
  • Class II, Group F - Atmospheres containing carbonaceous dusts, including carbon black, charcoal, coal, or coke dusts that have more than 8 percent total entrapped volatiles, or dusts that have been sensitized by other materials so that they present an explosion hazard.
  • Class II, Group G - Atmospheres containing combustible dusts not included in Group E or F, including flour, grain, wood, plastic, and chemicals.
Consult the National Electrical Code for more information on explosion proof regulations.

Explosion proof motors are UL listed in Class I, Division 1 Group D and Class II, Division 1 Groups F and G ratings; Class I, Division 1 Groups C and D and Class II, Groups F and G (56/140) ratings; or Class I, Division 1 Group D only.

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.
GENERAL PURPOSE, DEFINITE PURPOSE, AND SPECIAL PURPOSE:
There are three groups of motors as defined by NEMA. They are general purpose, definite purpose, and special purpose. General purpose motors can handle a wide variety of applications. They have NEMA torque, NEMA limited current, conservative temperatures, and rugged construction. Special purpose motors are more economical than general purpose. They have moderately high torque and are designed for specific loads. Definite purpose motors are designed for a specific application. Often they are restricted in use by their physical and electrical characteristics. Good examples would be oil burner motors, condenser fan motors, and double shaft fan and blower motors.
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

NEMA SERVICE FACTOR RATINGS:

The table below lists the NEMA service factors for single phase, dripproof motors. Totally enclosed and explosion proof motors have 1.0 service factors, except where noted.
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

OVERLOAD PROTECTION:

There are four choices in protection: manual (inherent type), automatic (inherent type), thermostats, and none. A manual overload must be physically reset to restart the motor. An automatic thermal overload will stop the motor when it is overloaded or overheated and restart it after the motor has cooled down. None means the motor has no protection. Thermostats are embedded in the winding and connected to the motor starter control circuit.

CAUTION NOTE!
A MOTOR WITH AN AUTOMATIC RESET PROTECTOR MUST NOT BE USED WHERE AUTOMATIC RESTARTING (AFTER MOTOR COOL-DOWN) WOULD ENDANGER PERSONNEL OR EQUIPMENT. SUCH APPLICATIONS SHOULD USE A MANUAL RESET PROTECTOR.

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.
ROTATION:
Most motors on this website are reversible by electrical reconnection or by physical orientation.
SERVICE FACTORS:
Motors are available in either NEMA or 1.0 service factors. A 1.0 service factor motor will perform to its nameplate rating. A NEMA service factor motor can exceed its horsepower rating periodically. (See table under NEMA Service Factor Ratings.)
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.

Back to Top