6b Motor Nameplate Handout.325.pdf

7/27/2019 6b Motor Nameplate Handout.325.pdf

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MOTOR NAMEPLATE INFORMATION

The motor nameplate is a description from the manufacturer listing specific information about the

motors 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, RPM, temperature rise or insulation

class and 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.

ELECTRIC MOTOR NAMEPLATE

MODEL 500 SPLIT PHASE TOTALLY ENCLOSED

FRAME TYPE INS. CLASS IDENTIFICATION NO.

145 KC J 2538094990298209

HP RPM VOLTS AMPS CYC S.F.

1 1725 115/230 15/7.5 60 1.25

DESIGN CODE: B PHASE EFF p.f.

DRIVE END BEARING BBD 116 1 62% 75%

OPP. END BEARING B0B 117 DUTY: CONTINUOUS

AMB 40 C NO THERMAL PROTECTION

R Manufacturer's Name, Model, & Serial #The manufacturer's name identifies the manufacturer of the motor.

Model number identifies the model of the motor produced by the specific manufacturer.

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.

R Motor Type

Identifies the type of motor/generally describes the starting method including:

DC Motors: Shunt Wound, Series Wound, Compound Wound, Permanent Magnet, 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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R Enclosure Type

The enclosure for the motor should be chosen to protect it from the expected operating environment.

Electric motors are required to operate in many different environments ranging from clean

and dry to extremely dirty, wet, and corrosive or from normal to very high temperatures.

Manufacturers provide a variety of motor enclosures designed to protect against various

types of adverse conditions.

The enclosure for the motor should be chosen to protect it from the expected operating

environment. The following table lists standard NEMA enclosures:

Standard Motor Enclosure Ratings

Types Characteristics

Open:

Drip-proofSplash-proof

Guarded

Semi-guarded

Fully Drip-proof

Guarded, externally

ventilated

Pipe ventilated

Weather protected type 1

Weather protected type 2

Totally Enclosed:

Non-ventilated (TENV)

Fan-cooled (TEFC)

Explosion-proof (TEXP)

Dust-ignition proof

Waterproof

Pipe-ventilated

Water-cooled

Water to air-cooled

Air-to-air cooled

Guarded TEFC

Encapsulated

Operate with dripping liquids up to 15 from vertical.Operate with splashing liquids up to 100 from vertical.

Guarded by limited size openings (less than 3/4 in).

Only top half of motor guarded.

Drip-proof motor with limited size openings.

Ventilated with separate motor-driven blower, can have other

types of protection.

Openings accept inlet ducts or pipe for air cooling.

Ventilating passages minimize entrance of rain, snow, and

airborne particles. Passages are less than 3/4 in. in diameter.

Motors have, in addition to type 1, passages to discharge

high-velocity particles blown into the motor.

Not equipped for external cooling.

Cooled by external integral fan.

Withstands internal gas explosion. Prevents ignition of

external gas.

Excludes ignitable amounts of dust and amounts of dust that

would degrade performance.

Excludes leakage except around shaft.

Openings accept inlet ducts or pipe for air cooling.

Cooled by circulating water.

Cooled by water-cooled air.

Cooled by air-cooled air.

Fan cooled and guarded by limited-size openings.

Has resin-filled windings for severe operating conditions.


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R 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.

NEMA Frame Designations

The standard NEMA Frame Size designation may contain:

a prefix of letters

the frame number

a suffix of letters

Frame Size Prefix

Letters or numbers appearing in front of the NEMA Frame Designation are the manufacturers.

They are not standardized within the NEMA designation and importance/meaning varies by

manufacturer.

Example: EF56C

The EF in the frame Designation EF56C is a manufacturers prefix indicating something

about the particular motor compared to other models produced by the same manufacturer.

Frame Size Number

In any standard frame number designation there are either two or

three numbers.

S Two Digit Frame Size - Indicates a fractional horsepowermotor less than 1 horsepower.

If the nameplate displays a two digit frame number, the

number is the distance from the center of the drive shaft to

the center bottom of the mount in sixteenths of an inch.

Example: EF56C > 56 divided by 16 = 3.5 inches from shaft to mount.


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S Three Digit Frame Size - indicates an integral horsepower motor 1 horsepower or greater.

For three digit frame sizes, divide the first two digits by four

to calculate the distance from the center of the drive shaft to

the center bottom of the mount in fourths of an inch.

Example: EF145C, > 14 divided by 4 = 3.5

inches from shaft to

mount.

The third digit is an indication of the distance between the

mounting holes parallel to the base.

Example: EF145C, > Mounting holes are 5 inches apart.

Frame Size Suffix

The suffix letter in the frame designation indicates the mounting type of the motor.

Today, new motors are designated "T" frame motors.

Between 1952 and 1964, the NEMA standards designated motors as "U" frame motors.

Prior to 1952, the "Original" standard was used.

Example: 143TD, > A current T-Frame motor using a D-Flange mount.

S No suffix or a T indicates a NEMA standard shaft

For motors that have a letter following the T:

S S indicates a NEMA standard "short shaft" for belt driven loads

S U would indicate a motor manufactured prior to 1965 meeting previous standards.

S Y indicates a non-NEMA standard mount which may be a special base, flange, or

face and a drawing is required to be sure of the dimensions.

S Z indicates a non-NEMA standard shaft and a drawing is required to be sure of the

dimensions.

S C indicates a standard NEMA face mount having a flat mounting surface machined

on the drive end with holes to allow easy, secure mounting to driven equipment.

S D indicates a standard NEMA flange mount having a flat mounting surface machined

on the drive end with holes to allow easy, secure mounting to driven equipment.

S

H indicates a frame with a rigid base having an F dimension larger than that of thesame frame without the suffix X.

S J indicates a NEMA C Face mount with a threaded shaft for a pump motor.

S JM, JP and JM indicate a close-coupled pump motor with specific dimensions and

bearings. The three designations differ in specific sizes.

S M or N indicates a NEMA mount that has a special flange for direct attachment to

fuel atomizing pumps on oil burners. M indicates a 6 3/4 inch flange while N

indicates a 7 1/4 inch flange.

R Insulation Class


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Type of insulation used in a motor depends on the operating temperature the motor will experience.

Standard NEMA insulation classes are given by alphabetic classifications according to the

maximum temperature rating and include A, B, F, H, or J.

They are an indication of the maximum temperature the motor insulation can withstand

without degrading its life.

S Class A insulation was the standard insulation used on older U Frame motors between

1952 and 1964.

S T Frame motors produced since 1964 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.

Insulation temperature charts are used to select insulation that will provide dependable motor life.

Example: A motor operating at 180 Degrees C will have an estimated life of:

300 hours with Class A insulation

1800 hours with Class B insulation

8500 hours with Class F insulation

Tens of thousands of hours with Class H insulation

R Horsepower Rating


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The full load output power at the shaft the motor can produce

without reducing its operating life.

If a motor produces more horsepower than it is rated

for, the service life will be reduced.

Motors below 1 horsepower are referred to as

fractional-horsepower motors and motors 1 horsepower

and above are called integral-horsepower motors.

NEMA has established standard power ratings from

fractional to thousands of horsepower.

Standard NEMA Horsepower Ratings

1 through 4000 Hp

1

1.5

2

3

5

7.5

10

15

20

25

30

40

50

60

75

100

125

150

200

250

300

350

400

450

500

600

700

800

900

1000

1250

1500

1750

2000

2250

2500

3000

3500

4000

When an application calls for a

horsepower falling between two sizes,

the larger size is chosen to provide the

appropriate power to operate the load.

Motor and engine manufacturers use different tests and definitions when describing power.

Motors have one power rating: Continuous Brake Horsepower

Engines will have several power ratings.


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R R.P.M.

RPM is the rated operating speed of the motor at full load.

Normal operating speeds for 60 hertz and 50

hertz motors vary depending on the number

of poles in the motor stator.

Some motors are dual speed motors and both

the speeds will be given.

The motor may be one of the following

NEMA classifications of speed

characteristics:

Constant Speed Motor:

One in which the speed of normal operation is constant or practically constant.

Examples include synchronous motors, induction motors with small slip design, or a DC

shunt wound motor.

Multi speed Motor:

One which can be operated at any two or more definite speeds, each being independent of the load

power required.

Examples include DC motors with more than two armature windings and AC induction

motors with windings capable of various pole groupings to accomplish the specific differentspeeds.

Varying Speed Motor:

One in which speed varies with the load, ordinarily decreasing as the load increases or increasing as

the load decreases.

Examples include series wound DC or repulsion AC motors.

Adjustable Varying Speed Motor:

One in which speed can be adjusted gradually, but once adjusted for a given load, will vary with the

change in load.

Examples include a wound rotor motor with an adjustable rheostat speed control.


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R Duty Rating

Motors are classified according to the length

of time expected to operate under full load.

The motor may be rated as either:

1. Continuous Duty

2. Intermittent Duty

Continuous Duty Motors

Continuous duty rated motors are rated to be

run continuously without any damage or

reduction in life of the motor.

General purpose motors will

normally be rated for continuous duty.

Intermittent Duty Motors

Intermittent duty motors are rated to be run continuously only for short time periods and then must

be allowed to stop and cool before restarting.

It is usually possible to reduce

the size, weight, and cost of a

motor by purchasing an

intermittent duty motor.

Intermittent duty motors are

available with maximum

operating times of 5, 15, 30, or

60 minute duties or times.

These motors are sometimes

used on devices like garbage

disposals or air compressors

where the motor operates for a

short period and shuts off afterthe job is accomplished and will

not be needed for an extended

time period.


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R Phase

Phase describes the necessary phase of the electric

power supply required for correct connection and

operation of the motor - Single or Three Phase.

Motors are designed for either single or three

phase operation as indicated on the nameplate.

Single Phase Motors

Single phase motors in general may be operated on one

phase of a three phase power supply with the correct rated voltage.

Single phase motors are used in smaller motor sizes, especially those less than 1 horsepower

or where three phase power is not available.

Single phase motors make up 80 percent of the U.S. motor market and are generally less than

10 horsepower in size unless special equipment or situations are applied.

Advantages of Three Phase Motors

Little or no voltage flicker when starting the motor.

Cost less to purchase than comparable size single phase motors.

Have longer life spans than single phase motors.


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R Rated Voltage(s)

This is the electrical supply voltage(s) at which

the motor is rated to operate.

AC motors are designed for optimum

performance with a specific voltage

applied from the electrical system.

NEMA Standard Motor Voltages

Single Phase Motors

115, 230, 115/230, 277, 460, and 230/460

Three Phase Motors up to 125 Hp

208, 230, 460, 230/460, 575, 2300, and 4000

Three Phase Motors above 125 Hp

460, 575, 2300, and 4000 volts

When dealing with motors, it is important to understand the difference between nominal

system and nameplate voltages.

Nominal

SystemVoltage

Nameplate

Voltage

120

208

240

480

600

2400

4160

6900

115

200

230

460

575

2300

4000

6600

Some older NEMA motors rated for 200, 220,

440 or 550 volts are sometimes encountered.

Motors with these markings can safely be

replaced by motors having the current NEMA

markings of 208, 230/460 or 575 volts.

Motors rated 115/230 volts and 230/460 volts

in most cases will operate satisfactorily on a

208 volt system but the torque will be 20 to

25% lower.

Operating below 208 volts may require a 208 Volt (200 Volt) motor or the use of the next

higher horsepower standard voltage motor.

Since line voltage will vary over a period of time due to power system load conditions, a motor must

cope with some voltage variation.

Standard motors are designed to tolerate voltage variations of plus or minus 10 percent.

S A motor with a nameplate voltage of 230 volts could be expected to give satisfactory

performance from 207 volts to 253 volts.


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R Hertz or Frequency

Identifies the rated frequency of the power source

to be used in cycles per second.

Motors intended for the North American

market are designed for operation on 60

hertz frequencies.

50 hertz indicates a motor made for export

out of the North American market.

NEMA standards specify motors should

operate satisfactorily under frequency

variations up to + 5% of rated frequency.

Operation outside of this limit results in a substantial speed variation and may cause

overheating and reduced torque.

R Current (Amperage) Rating

This is the motors rated current at full load and rated

voltage.

Other terms:

Full Load Amps (FLA)

Running Load Amps (RLA)

The motor will draw the rated current when

producing its rated output power when

supplied its rated voltage

When a motor draws more current than it is

rated, the motor is overloaded unless the motor has a service factor larger than 1.0.

Motor's drawing more current than their rated will generally have their windings damaged

due to the additional heat and the motors life will be reduced.


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R Service Factor

NEMA defines service factor as the amount of continual overload capacity designed into a motor.

It is the amount of overload over the nameplate rated power the motor can tolerate

continuously at rated voltage and speed without reducing its life.

S An indication of the motor's ability to exceed the mechanical power output rating on a

sustained basis without overloading or motor damage provided other service

parameters such as voltage, frequency, and ambient temperature are within norms.

S Service factor is a function of insulation class. Using Class F or H insulation instead

of Class B insulation allows the motor to withstand more internal heat without

reducing its operating life.

A service factor greater than 1.0 allows a margin for peak horsepower demand without

selecting the next larger motor size.

FLA can be multiplied by the service factor to determine the maximum current loading.

NEMA lists standard service factors for various size motors however many manufacturers

build and market motors with higher service factors than the NEMA standard.

S Common motor Service Factors include: 1.0, 1.15 and 1.25

Do not replace a motor of the same nameplate horsepower with one with a lower service

factor unless you know the new motor will not be overloaded.


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R Design Code Letter

An alphabetic letter used to indicate the

National Electric Code Design Code letter for

the motor.

When AC motors are started with full

voltage applied, they draw in-rush line

currents substantially greater than their

full load running current rating.

The Code letter of the motor is an

indication of the locked rotor KVA per

horsepower for the particular motor and

is a function of the motors design.

The code letter rating gives a good indication of the starting current a particular motor will draw.

A code letter at the beginning of the alphabet indicates a low starting current and a letter

lower than F indicates a high starting current for the particular motor.

The motor's Code Letter is helpful in determining the maximum rating of the motor's

electrical circuit protection.

A replacement motor should have the same rating as its predecessor or the circuit

fuses/breakers and wire may not be sized appropriately and have to be replaced.

Code Letters for Locked Rotor kVA are as follows:

Code

Letter KVA/Hp

A: 0.00-3.14

B: 3.15-3.54

C: 3.55-3.99

D: 4.00-4.49

E: 4.50-4.99

F: 5.00-5.59

G: 5.60-6.29

Code

Letter KVA/Hp

H: 6.30-7.09

J: 7.10-7.99

K: 8.00-8.99

L: 9.00-9.99

M: 10.00-11.19

N: 11.20-12.49

P: 12.50-13.99

Code

Letter KVA/Hp

R: 14.00-15.99

S: 16.00-17.99

T: 18.00-19.99

U: 20.00-22.39

V: 22.40-AND UP

Starting kVA/HP (from chart) X Motor HP 1000 for single phase

Locked Rotor Amps = ------------------------------------------------------ X or

Rated Volts 577 for 3 phase


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R Power Factor

The motor's power factor at rated load and voltage.

Motors are inductive loads and have power factors less than 1.0, usually between 0.5 and

0.95 depending on their rated size.

S The higher the rated horsepower, in general the higher the power factor of the motor.

Most AC motors require reactive power from the supply system to develop magnetic fields.

S Reactive power does not provide any useful mechanical work but is required to make

the motor operate.

S Useful mechanical work is developed from Real Power (kW) supplied by the supply

system and is measured in kilowatts.

S The electrical supply system must provide both Real (kW) and Reactive Power

(kVAR) to operate the motor.

The power factor of induction motors varies with load and drops significantly below 75%

load.

Some utilities charge

penalties if plant power

factor is below a certain

percent.

This gives the customeran incentive to apply

power factor correction

(capacitors).


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R Connection Diagram

Connection diagrams can be found on the

nameplate of some motors, or the diagram may be

located inside the motor conduit box or on a special

connection plate.

The diagram will indicate the specific

connections for dual voltage rated motors.

The diagram may also provide the standard

direction of rotation for the motor shaft, clockwise, or counter clockwise.

Unless stated otherwise, rotation is specified from the end view of the shaft extension.

Some motors can operate in either direction depending on how the connections to the motor

are made and this information may also be given on the nameplate.

R Ambient Temperature

The abbreviation AMB on a motor nameplate provides the maximum ambient temperature the motor

should be operated within.

Ambient means the temperature of the air surrounding the motor.

In general, maximum ambient temperature for motors is 40 Degrees C or 104 Degrees F

unless the motor is specifically designed for a different temperature and indicates so on the

nameplate.

Operation of a motor at ambient temperatures above that given on the nameplate may or may

not affect the life of the motor depending on whether the motor is operating at or near its

rated full load.

Motors operating at or near rated full load will have reduced life if operated at ambient

temperatures above their ratings.

If the ambient temperature is over 104 degrees F, a higher horsepower motor or a special

motor designed for operation at higher ambient temperatures must be used.

Motors for use in abnormally hot places are usually designed to accommodate the higher

ambient by having a lower winding temperature rise.

If the ambient temperature is above 122 degrees F, special consideration must also be made

of the lubricant.


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R 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.

It can also be thought of as the amount which

a motor operating under rated conditions, is

hotter than its surrounding temperature.

The ambient temperature has very little, if anything, to do with the motors actual temperature

rise.

Certain inaccessible spots of a motor winding are considered to be the hottest spots of the

insulation system. These areas are called hot spots.

S For the reason a 10 Degrees C allowance is made for uneven heating in the motor

called a hot spot allowance.

S The total temperature rise equals the rise due to the load on the motor plus the hot

spot allowance.

S Generally you do not have any control over temperature rise due to load or hot spot

allowance.

However, you can limit motor temperature and maximize life by selecting a motor that can

produce enough horsepower without being overloaded and by making sure the motor runs in

ambient temperatures at or below the nameplate rating.

A good rule to remember is that for every 10 degrees C the operating temperature increases

over rated temperature, motor life will be cut in half.


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R Thermal Protection

Indicates if the motor has its own internal automatic or manual thermal overload protection device.

There are several types of protective devices than

can be built into the motor and used to sense

excessive (overload) temperature rise, and/or current

flow.

These devices disconnect the motor from its power

source if they sense the overload to prevent damage

to the insulation of the motor windings.

This prevents the motor from getting to hot and

damaging the windings or causing a possible fire.

The primary types of thermal overload protectors include automatic and manual reset devices that

sense either current or temperature.

With automatic reset devices, after the motor cools,

this electrical circuit interrupting device

automatically restores power to the motor.

With manual reset devices, the electrical circuit

interrupting device has an external button located on

the motor enclosure that must be manually pressed to

restore power to the motor.

Some low cost motors have no internal thermalprotection and rely on external protection between

the motor and the electrical power supply for safety.

Never bypass a thermal protective device because of nuisance tripping of the motor.

The tripping is generally a sign of some other problem, such as overloading, buildup of dirt

and debris, or lack of proper ventilation.

Manual reset protection should be provided where automatic restart of the motor after it cools down

could cause personal injury should the motor start unexpectedly.


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R Efficiency

The efficiency of a motor is the ratio of mechanical power output the motor can produce to the

electrical power input required by the motor.

Think of this as the useful work the motor

produces versus the energy the motor

consumes expressed as a percentage.

Most motors operate near their maximum

efficiency at rated load.

Motor efficiency varies from the nameplate

value depending on the percentage of the

rated load applied to the motor.

NEMA standard MG1-12 provides instructions for manufacturers in establishing the value of

efficiency for a given size and type of motor.

The efficiency given on the nameplate

cannot exceed the nominal (average)

efficiency for a large population of

motors of the same design when tested

by the manufacturer.

Variations in motor efficiency exist

from motor to motor due to

manufacturing tolerances, raw material

variations, and process changes.

It is generally reasonable to expect

difference of + 1% for a motors

efficiency based on the nominal

efficiency on the nameplate.


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R Special Order Motors

Electrical motors are classified into several groups depending on the type of service for which they

are designed.

Standard or General Purpose motors

General Purpose motors are designed for general use without restrictions for particular applications

and meet certain specific NEMA standards.

General purpose motors are less expensive, use proven designs and are available on shorter

lead times than other service classifications of motors.

Definite Purpose Motor

A Definite Purpose Motor is designed in standard ratings and with standard operating characteristics

for use under service conditions other than usual or for use on a particular type of application.

Common definite purpose motors include

- automotive industry

- chemical industry

- food processing industry

- farm duty

-other categories.

Special Purpose Motor

A Special Purpose Motor is one with special operating characteristics or special mechanicalconstruction or both which is designed for a particular application and which does not meet the

definition of a general or definite purpose motor.

Special Order Motors

Motors can be ordered with an almost unlimited number of variations to fit special applications

where a standard motor is not suitable.

Each motor supplier is more than happy to provide specific information on availability, lead

time and price for special order motors.

Documents

6b Motor Nameplate Handout.325.pdf