MAGM 225

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MAGM 225
Motor Nameplate Information
Mr. Conrado
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Nameplate Information

• The nameplate is a description from the
  manufacturer listing specific information about
  the motor characteristics.
• Motor standards require motors to be shipped with
  a nameplate when new.
• The National Electrical Code requires specific
  items on a motor nameplate including
  manufacturer, voltage, full load amps, frequency,
  phase, temperature rise, ambient temperature,
  duty rating, rated horsepower, and locked rotor
  design letter.
• Additional information will normally appear
  including service factor, enclosure type, frame
  size, connection diagrams, and other unique or
  special features.

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Manufacturers Name, Model, Serial Number

• The manufacturers name identifies the
  manufacturer of the motor
• The model number identifies the model of the
  motor produced by the specific manufacturer.
• The Serial number is specific for the
  manufacturer and identifies the specific motor
  and is useful in establishing the age of the
  motor for replacement parts and warranties.

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Motor Type

• Identifies the type of motor
• Generally describes the starting method including
• DC Motors - Shunt wound, Series wound, Compound
  wound, Permanent Magnet, and Universal.
• Single Phase Motors Split phase, Shaded pole,
  Permanent Split Capacitor, Capacitor Start,
  Capacitor Start-Capacitor Run, Universal
• Three Phase Motors Squirrel Cage Induction,
  Wound Rotor, Synchronous, Reluctance.

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Enclosure Type

• The enclosure for the motor should be chosen to
  protect the motor from the expected operating
  environment.
• See the next slide for NEMA enclosure ratings

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NEMA Frame Size Designation

• NEMA has assigned a series of standardized
  numbers and letters to describe various
  dimensions and mounting types of motor frames.
• When changing a motor, selecting the same frame
  size regardless of manufacturer ensures the
  mounting mechanism and hole positions will match.
• As a general rule, as frame size increases, so
  does physical size and horsepower of the motor.
• There are many motors of the same horsepower and
  size built with different frame sizes so they can
  be mounted in various manners.

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NEMA Frame Size Designation

• NEMA Frame Designations may contain
• A prefix of letters
• The frame number
• A suffix of letters

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NEMA Frame Size Designation

• Frame Size Prefix
• Letter or number prefixes before the NEMA Frame
  Designation are the manufacturers and are not
  NEMA standardized. The prefix meanings vary from
  manufacturers
• Example EF56C

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NEMA Frame Size Designation

• Frame Size Number
• Two Digit Frame Size Indicates a fractional
  horsepower motor of less than 1 horsepower.
• This number is the distance from the center of
  the drive shaft to the center of the bottom of
  the mount in sixteenths of an inch.
• Three Digit Frame Size Indicates an integral
  horsepower motor 1 horsepower or greater
• Divide the first two digits by four to calculate
  the distance from the center of the driveshaft to
  the center bottom of the mount in fourths of an
  inch.
• Example 145 14 divided by 4 3.5 inches from
  the shaft to the mount.

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NEMA Frame Size Designation

• Frame Size Suffix - Indicates the mounting type
  of the motor.
• Modern motors (post 1964) are designated with a
  T
• ExampleEF145TD A current T-Frame motor using a
  D-Flange mount

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Insulation Class

• The type of insulation used in a motor depends on
  the operating temperature the motor will
  experience.
• Standard NEMA insulation classes are given by
  alphabetic classification according the the
  maximum temperature rating and include, A, B, F,
  H or J.
• These are an indication of the maximum
  temperature the motor insulation can withstand
  without degrading its life
• Modern T frame motors use class B insulation as
  the standard.
• Do not confuse the NEMA insulation classes with
  the NEMA motor designs which are also given by
  letters.

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Horsepower Rating

• The full load output power at the shaft the motor
  can produce without reducing the motors
  operational life.
• If a motor produces more horsepower that it is
  rated for, the service life will be reduced.
• Motors below 1 horsepower are referred to as
  fractional horsepower motors and motors above 1
  horsepower are referred to as integral horsepower
  motors.
• NEMA has established standard power ratings from
  fractional to thousands of horsepower.
• Motors have one power rating Continuous Brake
  Horsepower
• When an application call for a horsepower between
  two sizes the larger size is chose to provide the
  appropriate power to operate the load.

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RPM

• RPM is the rated operating speed of the motor at
  full load.
• Normal speeds for 60 hertz motors vary depending
  on the number of poles in the motor stator.
• Some motors are dual speed motors and both the
  speed will be given
• The motor may be one of the following NEMA
  classification of speed characteristics

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RPM

• Constant Speed Motor
• One in which the speed of normal operation is
  constant or practically constant.
• Multi-Speed Motor
• Can operate at any two or more definite speeds,
  each being independent of the load power
  required.
• Varying Speed Motor
• Speed varies with the load.
• Adjustable Varying Speed Motors
• Speed can be adjusted gradually, but once
  adjusted for a given load, will vary with the
  change in load.

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Duty Rating

• Duty rating is classified as the length of time
  the motor is expected to operate under full load.
  Motors can be classified as either continuous or
  Intermittent Duty.
• Continuous Duty Rated to be run continuously
  without any damage or reduction in life of the
  motor.
• Intermittent Duty Rated to be run continuously
  only for short time periods. They must then be
  allowed to stop and cool before restarting.

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Phase

• Phase describes the necessary phase of the
  electric power supply required for correct
  connection and operation of the motor Single or
  Three Phase
• Single Phase- Generally may be operated on one
  phase of a three phase power supply with the
  correct voltage.
• Generally used in smaller motor sizes of less
  than 1 horsepower and where three phase in not
  available.
• Three Phase The advantages of Three Phase often
  dictate its use
• Little or no voltage flicker when starting
• Cost less to purchase than comparable single
  phase motor
• Have longer life spans than single phase motors

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Rated Voltage

• This is the electrical supply voltage at which
  the motor is rated to operate.
• NEMA Standard Motor Voltages
• Single Phase
• 115, 230, 115/230, 277, 460, 230/460
• Three Phase up to 125HP
• 208, 230, 460, 230/460, 575, 2300, 4000
• Three Phase above 125HP
• 460, 575, 2300, 4000

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Rated Voltage
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Frequency

• Identifies the rated frequency of the power
  source to be used in cycles per second and
  measured in Hertz.
• North America 60Hz
• /- 5 of rated frequency is acceptable

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Current Rating

• This is the motors rated current at full load and
  rated voltage and is measured in Amps.
• The motor will draw the rated current when
  producing its rated output power when supplied
  its voltage.
• If the motor draws more current than it is rated,
  the motor is overloaded unless the motor has a
  service factor larger than 1.0.
• A motor that draws more current than rated will
  generally have their windings damaged due to the
  additional heat and the motors life will be
  reduced.

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Service Factor

• NEMA defines service factor as the amount of
  continual overload capacity designed into the
  motor.
• The amount over the overload over the nameplate
  rated power the motor can tolerate without
  reduced motor life.
• A service factor greater than 1.0 allows for a
  margin of peak horsepower demand without
  selecting the next larger size motor.

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Design Code

• An alphabetic letter used to indicate the NEMA
  design code for the motor.
• A replacement motor should have the same rating
  as its predecessor or the circuit fuses/breakers
  and wire may not be sized appropriately.
• The code letter is an indication of the locked
  rotor KVA (kilo-volt-amps) per horsepower for the
  motor and its design function.

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Power Factor

• The motors rated power factor at rated load and
  voltage
• The higher the rated horsepower, in general the
  higher the power factor of the motor.

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Ambient Temperature

• The maximum ambient temperature the motor should
  be operated within.
• Ambient Temperature of the air surrounding the
  motor.
• Generally standard is 104F or 40C.
• If the motor is operated at full load and above
  the ambient temperature rating service life will
  be reduced.

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Temperature Rise

• Temperature rise is the increase in the motors
  internal temperature as it operates due to
  current flowing through the windings.
• The ambient temperature plus the temperature rise
  is the maximum temperature at which the motor
  should operate at full load.

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Thermal Protection

• Indicates if the motor has its own internal
  automatic or manual thermal protection device.
• Can be used to sense excessive load, temperature
  rise, and/or current flow.
• These prevent the motor from getting too hot and
  damaging the windings or causing a fire.
• Never bypass a thermal protective device.

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Efficiency

• The ratio of mechanical power output of the motor
  compared to the electrical input.

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Connecting Diagram

• Often connection diagrams can be found on the
  nameplate or located inside the motor conduit
  box.
• Indicates the specific connections for dual
  voltage motors.
• May also provide the standard direction of
  rotation for the motor shaft.
• Some motors can operate in either clockwise or
  counter-clockwise direction