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How do I work out what electric motor frame size I need?

For anyone not used to ordering electric motors, calculating the frame size required can be very confusing, with several pieces of information to consider.

We’ve put together this quick guide to working out electric motor frame sizes so you can be sure you’re ordering the right equipment for your application.

Electric motors are designated by a full model code. For this we’ll use a Gibbons three-phase four-pole electric motor with model number MS802-4 as an example. This motor has the following characteristics:

  • MS - The initial letter(s) will be manufacturer specific and refer to model type.
  • 80 - The first two numbers denote the motor’s frame size (the distance from the underside of the feet to the centre of the shaft, measured in millimetres). This tends to start at 56 and can be anything up to 450.
  • 2 - The next digit refers to lamination pack length, (1 being the shortest). Pack length is usually 1, 2 or 3 but can be even greater. Designation for pack length varies between manufacturers, with some using a numbered system while others prefer letters.
  • 4 - The final digit refers to pole speed, which will usually be two, four, six or eight.

For any questions on motor sizing, give the experts at Gibbons a call. One of our engineers will be happy to help you select the ideal motor from our high-efficiency range, so call 01621 868138 or email today.

Electric Motors

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