Motors Name Plates

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Author:
johnbowens
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105828
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Motors Name Plates
Updated:
2011-12-25 12:46:34
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Motors Nameplate Construction
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Motors 4th year IBEW NJATC curriculum: Motors second edition, ATP ISBN: 978-0-8269-1982-3
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  1. Concentrations of flux become greater when what increases? NJATC ATP, Motors 2nd edition, PP 8
    Permeability.
  2. Why are permanent magnets not used in transformers? NJATC ATP, Motors 2nd edition
    Heat and vibration can demagnetize a permanent magnent.
  3. Positive to negative electron current flow is described as which theory? Electron Current flow or Conventional current flow? NJATC ATP, Motors 2nd edition, PP 11
    Conventional.
  4. With a DC motor, what is used to reverse the direction of current? NJATC ATP, Motors 2nd edition, PP 15
    Commutator.
  5. what is the first thing that should be checked on a motor when troubleshooting? NJATC ATP, Motors 2nd edition, PP 22

    Actual voltage should be within how much of the motor's nameplate voltage? NJATC ATP, Motors 2nd edition, PP 23
    Nameplate rated voltage should be checked against supply voltage.

    10 percent.
  6. On a three phase motor the applied voltage must be what? NJATC ATP, Motors 2nd edition, PP 23

    What is the Percent allowed voltage unbalance to current unbalance ratio? NJATC ATP, Motors 2nd edition, PP 23
    balanced, or high operating temperatures may result. Every 1 percent voltage unbalance will equal 6 - 10 percent current unbalance.
  7. DC Motors will typically use what voltages? NJATC ATP, Motors 2nd edition, PP 24
    24, 48, 90, & 180.
  8. The current rating of a motor is what? NJATC ATP, Motors 2nd edition, PP 24
    The amount of current the motor draws when full rated power output is being used at the shaft.
  9. The LRC code letter is omitted on what type of motors? NJATC ATP, Motors 2nd edition, PP 25
    poly-phase wound-rotor motors and motors less than 1/2 HP rated.
  10. Motors typically toleratre a plus / minus what percent frequency variation without affecting the motor's load operation? NJATC ATP, Motors 2nd edition, PP 26
    5 percent
  11. variable speed drives are designed to maintain what? NJATC ATP, Motors 2nd edition, PP 26
    the motor's nameplate volts-per-hertz ratio (V/Hz).
  12. A lower frequency will do what to motor speed and torque? NJATC ATP, Motors 2nd edition, PP 26
    decrease motor speed and increase torque.
  13. single phase motors are used primarily where? NJATC ATP, Motors 2nd edition, PP 27
    in applications requiring power of less than 1 HP and where 3-phase power is not available.
  14. The nameplate power rating of a motor is abbreviated as what on a motor? NJATC ATP, Motors 2nd edition, PP 28
    HP or KW.
  15. The power rating for a motor is listed on the nameplate for motors over what HP? NJATC ATP, Motors 2nd edition, PP 28
    1/8 hp.
  16. The minimum voltage rating of the drive versus the minimum power rating of the drive are different in what way for motors? NJATC ATP, Motors 2nd edition, PP 29
    The voltage rating of a motor and drive need not match but a minimum power rating must be equal or greater than the power rating of the motor
  17. In U.S. markets, motors rated at less than what 1/20 HP are rated in what? NJATC ATP, Motors 2nd edition, PP 29
    watts.
  18. There are two types of usage ratings for motors. What are they? NJATC ATP, Motors 2nd edition, PP 29

    What about the first type must be remembered?
    General purpose and definite-purpose.

    General purpose motors are not designed to operate at temps over 40 celcius, or above 3300 ft elevation, and require free air flow and a rigid mounting surface.
  19. What rating defines the amount of load, beyond the rated load, that can be placed on a motor without causing damage? NJATC ATP, Motors 2nd edition, PP 30
    Service factor rating (1.00, 1.15, 1.25, and 1.35).
  20. Speed rating of a motor is what? And is abbreviated on the nameplate as what? NJATC ATP, Motors 2nd edition
    The approximate speed at which the rotor of a motor rotates when delivering rated power to a load. Abbreviated as RPM on the name plate
  21. Slip is what? NJATC ATP, Motors 2nd edition, PP 30

    Non-synchronous motors typically slip between what percentage?
    The difference between synchronous and operating speed of the motor

    Non-synchronous motors slip between 3-5 percent
  22. The sychronous speed of an AC motor is based on what? Defined as? NJATC ATP, Motors 2nd edition, PP 30/ glossary
    The number of stator poles and the applied frequency. It is the speed of the field as it rotates around the stator.
  23. Reduced cooling problems are solved by using a motor rated for operation with what? NJATC ATP, Motors 2nd edition, PP 31
    electric motor drives.
  24. What is an easy way to identify a commercial versus industrial motor? NJATC ATP, Motors 2nd edition, PP 31
    Commercial use sealed bearings and industrial motors use lubricated bearings.
  25. What defines the amount of time a motor can run without having to be turned off in order to allow cooling? NJATC ATP, Motors 2nd edition, PP 31
    operating time rating or duty cylce. Abbreviated as DUTY, DUTY CYLCE, or TIME RATING.
  26. The sychronous speed of a motor, based on the number of stator poles and applied frequency, increases or decreases as the number of stator poles increase? NJATC ATP, Motors 2nd edition, PP 31
    Decreases by the ratio of poles in the previous motor to the new number of poles. Example 2 poles to 4 poles. (3600 rpm to 1800 rpm) So half of 3600 equals 1800.
  27. Motor efficiency is what? NJATC ATP, Motors 2nd edition, PP 32
    Ratio of motor power output to supply power input.
  28. A continous duty motor runs how long continually versus a continous load? NJATC ATP, Motors 2nd edition, PP 32
    Operation at a substantially constant load for an indefinitely long time, versus a continous load which runs for 3 hours or more.
  29. Three electrical problems associated with motor over heating are what? NJATC ATP, Motors 2nd edition, PP 35
    • voltage unbalance
    • Phase loss
    • surge voltages
  30. What, regarding wave forms, may cause motor overheating? NJATC ATP, Motors 2nd edition, PP 35
    Nonsidusoidal waveforms produced by electric motor drives. Waveforms containing multiple sine waves of different frequencies.
  31. Concerning Motor frames and NEMA ratings on motors over 200 HP, what must be remembered? NJATC ATP, Motors 2nd edition, PP 37
    That these motors are special ordered and not standard.
  32. Fractional HP and Integral HP motors have how many digit frame numbers representing what? NJATC ATP, Motors 2nd edition, PP 36
    Fractional - 2 digit (usually less than 1HP and 3.5 inches from base to shaft) representing 1/16th of an inch

    Integral - 4 digit, where the first two digits represent 1/4's of an inch base to shaft
  33. What design motor is used the least? NJATC ATP, Motors 2nd edition, PP 40

    Design A through D motors have what allowable slip?

    Design D motors are rated at what FLC?
    Design A is used the least

    5 percent slip is allowed with design A through D motors.

    Design D motors are rated at 275% full load and high inertia starts for applications such as cranes and hoists.
  34. Electrical ratings included on a motor nameplate include what? NJATC ATP, Motors 2nd edition, PP 51
    voltage, current, fequency, and phase rating.

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