How to read a motor nameplate

The motor nameplate reading shows what the motor is capable of, or it can also be considered as the performance characteristics of a motor. In certain cases it will be very difficult to read a motor nameplate, different manufacturers would display the motor information differently.

The motor nameplate would have certain parameters like

  • Voltage
  • Frequency
  • Current
  • Motor classification
  • kilowatt
  • Phase
  • Serial number
  • Frame
  • Efficiency
  • Bearing
  • Insulation class/ Ambient temperature  
  • Degree of protection
  • Duty
  • RPM

The nameplate will be placed in the motor and in the above image, in the middle of the nameplate we can see the manufacture’s name. If we look at the top left we can see CT & VT, in which the CT is the constant torque and VT is the variable torque and in a normal nameplate, the values will be displayed in it. According to this value, we can determine its operating range and also the devices that can be used.  The nameplate for each motor will be different, so if we take two motors from different manufacturers the items displayed won’t be the same but the important details will be there. In the above image, we can see a high voltage and low voltage section and this provides details about the low and high voltage operating range of the motor. We can also see the model number and the serial number of the motor. Below that we can see the motor type and according to that we could know for which applications this motor will be suited. We can also see a code section in the nameplate it displays the value of the amps that the motor will draw to energize, but if we are using a VFD we don’t need to care about this. In the image, we can see the EFF and this stands for the efficiency, and a percentage will be displayed in this section and this percentage will be the amount of energy that the motor will use to do its operation. The SF stands for service factor which would display the percentage value that the motor can operate beyond its rated current.

We can also see the phase and horsepower section in the motor and it shows the motor phase as if it is three-phase or not and also the horsepower it creates. We can also see the RPM and this shows the motor’s RPM and this value could change according to the given frequency. The INSL in the nameplate stands for insulation and it would display the insulation class and it could be F or H which shows the temperature that the insulation could handle. The amps and volt section shows the motor’s operating range. We can also see the bearing and it will display the bearing number. The nameplate details will be different for each manufacturer like it won’t show certain parameters but we can see major parameters in all the nameplates such as voltage, frequency, amps, phase, and these details are very important for the motor connection.


post-graduate in Electronics & communication.

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