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Understanding a single-phase electric motor nameplate

The nameplate attached to an electric motor contains vital information to help suppliers and end users ensure it produces the highest possible level of performance and efficiency.

But what do all those letters, numbers and symbols actually mean? The information given on a nameplate differs depending on the kind of motor, and no two manufacturers will use the same format. However, this guide should give you a good idea of what to look out for.

In this blog we’re explaining the nameplate on a typical Gibbons single-phase squirrel cage induction motor.


  • MY - The initial letter(s) are manufacturer specific.
  • 80 - The first numbers denote the motor’s frame size (the distance, in millimetres, from the underside of the feet to the centre of the shaft). This generally begins at 56 and can be anything up to 450.
  • 2 - The next digit refers to lamination pack length, with 1 being the shortest. Pack length is normally 1, 2 or 3 but can be even greater. Some manufacturers use a numbered system while others prefer letters.
  • After these numbers there may be a letter (M, L or S) which tells us the length of the foot fixings – medium, long or short. Two or three of these letters can be displayed depending on the number of fixing holes.
  • 4 - The final digit refers to pole speed, which will usually be two, four, six or eight.


This is the rated horsepower. 1 hp = 746 watts.


The rated output in kilowatts.


The rated voltage.


The full-load current (amps).


Frequency. This is always 50 Hz in the UK and Europe, though some countries in Asia, the Middle East and the Americas use 60Hz.


Shaft speed (revolutions per minute).


Ingress Protection rating of a motor enclosure from objects, dust and moisture. The digits represents protection against ingress of solid objects and liquids respectively.


This is the insulation class which indicates resistance to thermal failure. It is commonly F, covering temperatures up to 155°C, although motors can be rated H for a maximum 180°C.


These represent the rating of the capacitor in microfarads (µF) and volts (V).


This box denotes the duty cycle rating according to the International Standard IEC 60034-1. This ranges from S1 to S10, with S1 being continuous duty and S2-S10 providing shorter duties.


The manufacturer’s unique serial/reference number. This helps the company that produced the motor diagnose faults and provide an identical replacement if necessary.

If you have any questions about electric motors, give us a call on 01621 868138 or email and one of our friendly team will be happy to help.


Electric Motors


  • Date: 20 March 2017 Geoff
    Gweat work
  • Date: 9 August 2018 Abarna
    Mostly the nameplates are used for understanding the specifications in motors.

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