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How to select the ideal variable-speed drive for your application

When choosing a variable-speed drive for an electric motor-driven application, it must be perfectly matched to the job. Whether the drive is controlling the speed of a fan, pump, conveyor, mixer or other piece of equipment, a lack of precision at this stage can cause the application to be inefficient and costly, so follow this handy guide and make the right choice.

1. Identify your application

Consider the type of process and the load demands. This will generally be one of the following:

  • Constant torque, for fixed volumes
  • Quadratic load, including centrifugal pumps, fans and most mixers
  • Constant power, normally used in processes where a material’s diameter changes as it is rolled up or unfurled

2. Collect load data

This should include speed, inertia, acceleration/braking and overload requirements

3. Collect motor data

Check the installed motor’s nameplate for information on torque, output, voltage, speed and insulation

4. Select a drive

Armed with the information from steps 1-3, you should be able to order a drive to match your application. However, there are some additional considerations you may want to make. These include:

What kind of interface is required?

Depending on the complexity of your application, there are a variety of keypads available, from simple to full text assisted. Straightforward processes may only need a few parameters to be adjusted, while some food and beverage machines will require an extensive menu of recipes.

Does the drive have the right level of safety?

The ‘safety first’ nature of modern industry means that appropriate VSD safety functions, including safe torque off (STO) are critical.

Does the drive have the correct enclosure?

Drives are rated for Ingress Protection, which denotes the enclosure’s resistance to solid particles and liquid. For example, a drive situated in a food processing plant that is routinely subject to high-pressure wash-down spray will need a high level of liquid ingress protection.

If you need further information on VSD selection, we have the expertise to help you make the right choice. As a founder member of the Authorized Value Provider network, we’re approved to stock and distribute ABB drives, as well as offer guidance on all aspects of VSD ownership.

Discuss your drives requirements by calling Alan Roberts on 07966 468430 or email

Variable-Speed Drives, Electric Motors, Pumps & Controls

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