Motor Nameplate - Meaning and details

Understanding motor’s nameplate

You can fine a nameplate of a motor in motor body. Every essential data is given on this nameplate. Some times it’s difficult to understand, but it is very important. You need this data for maintenance, installation or change any kind of equipment. Engineers should concern about this data. The information of a motor nameplate is not same for all motor. Different manufacturers give different information. But most of the case, there are 15 essential information given on motor nameplate.

1. Voltage
2. Frequency
3. Phase
4. Current
5. Power factor
6. kW or Horsepower
7. Full-load speed
8. Efficiency
9. Duty
10. Insulation class
11. Maximum ambient temperature
12. Enclosure
13. Frame
14. Bearings
15. NEMA // Service factor

11. Voltage

The operation voltage is given on motor nameplate. This data shows you about supply voltage for operate the motor.

    2. Frequency

Normally, the frequency of a motor is 50 or 60 Hz. You can find 50 Hz frequency or 60 Hz frequency or both in a same nameplate. If there are both frequencies, then other parameters that will differ at 50 Hz or 60 Hz and it must be indicated on the nameplate.

33. Phase

This data shows you the number of supply line connected in the motor. It is may be Single phase or Three phase.

44. Current

This parameter represents you the rated Current which is corresponds to the rated power. These rated amperes sometime vary for unbalanced phase or unbalanced voltages.

55. Power factor

Power factor is represented on the nameplate as “PF” or “P .F” or “cos φ”. Power factor is an expression of the ratio of active power (W) to apparent power (VA) expressed as a percentage.

66. kW or horsepower

The power rating of motor’s mechanical output is shows in this data. It may be in kW or Horsepower (HP) unit.

77. Full-load speed

Rated full-load torque is delivered full-load speed at rated power output. The unit of full-load speed given in RPM (Revolutions per Minute).

88. Efficiency

Efficiency of motor expressed as a percentage. It is the result of motor’s output power divided by input power and multiplied by 100. The manufacturers are responsible for the guarantee of motor efficiency within a certain tolerance band.

99. Duty

This parameter defines the length of time during which the motor can carry its nameplate rating safely. In many cases, the motor can do it continuously, which is indicated by an S1 or “Cont” on the nameplate. If nothing is indicated on the nameplate, the motor is designed for duty cycle S1.

110. Insulation class

The standard classification of the thermal tolerance of motor winding is expressed by Insulation Class. Insulation class expressed with “A”, “B”, “F” or “H” and these alphabets are stands for 105, 130, 155 and 180 ˚C.

111. Maximum ambient temperature

The rated temperature indicates in motor nameplate is the maximum ambient temperature which a motor can operate. The motor can run and still be within the tolerance of the insulation class at the maximum rated temperature.

112. Enclosure

Motor’s degree of protection from environment and its method of cooling is classifies in nameplate. Enclosure is shown as IP or ENCL on the nameplate.

113. Frame

The Data of frame size on the nameplate is an important piece of information. It determines mounting dimensions such as the foot hole mounting pattern and the shaft height. The frame size is often a part of the type designation which can be difficult to interpret because special shaft or mounting configurations are used.

114. Bearings

Bearings are the important parts of a motor. You should know the bearing number for maintenance the motor. In the nameplate, bearing number is usually given for both the drive-end (DE) bearing and the bearing opposite the drive-end, non drive- end (NDE).

115. Service factor

In the nameplate, motor’s power rating is given with service factor 1.0; it means that motor is designed to operate at its 100% of its rated power. Sometimes we need a motor that can exceed the rated power. In this case, we need to select a motor with service factor 1.15; this motor can operate at 15% higher than the motor’s nameplate power. It is harmful and reduced motor’s life if we continuously operating in higher of its rated power.