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Motors and drives

Review efficiency of motors and drives in your organisation for energy savings.

Energy efficient motors & drives

Running motors and drives uses almost two thirds of the electricity consumed by UK industry. In fact the cost of running a motor for a year can be ten times what it cost to buy in the first place. The efficiency of your motor operation is therefore of critical importance to the lowering of your carbon footprint and reduction of your energy bills.

Motors and drives technology overview guide


Published May 2018

This 32-page technology overview guide introduces the main energy saving opportunities for motors and drives. By taking simple actions you can save energy, cut costs and may increase profit margins.

This overview guide is intended for managers and users of electric motor systems. Both beginners and experts will benefit as it introduces the technologies and outlines some common energy saving opportunities, many of which apply in both small commercial and large industrial applications.

This guide focuses on the AC induction motor although many of the energy saving suggestions may also be applied to other motor types.

Guide contents:

  • Motors and drives in industry
  • Technology overview
    • Understanding the motor
    • Variable speed drives (VSDs)
    • System losses
    • Load types
  • Opportunities for energy saving in motor systems
    • Switch-off policy and stop-start Control
    • Minimising demand and process optimising
    • System design and optimisation
    • Variable speed drives, integrated motor – drive units and soft starters
    • Usage and housekeeping
    • Motor system maintenance
  • Opportunities for energy savings with motors
    • Regulations affecting motor efficiency and the market
    • Energy saving opportunities
    • Electrical power quality
    • Motor sizing and loading
  • Opportunities for energy savings with transmissions
    • Use the correct transmission system
    • New equipment
    • Specifying new motor-driven and drive systems
    • Life cycle costing
  • Motor management policies
    • Introduce a motor management policy
    • Rewind or replace?
  • Monitoring
    • Carrying out measurements
    • Condition monitoring and analysis
  • Your next steps
  • Glossary

Publication date May 2018; Publication code CTV048.

Information in this report was correct at the time of publication

Download the guide:

Motors and drives: energy saving tips

Start with the following recommendations when reviewing motors and drives in your organisation:

1. Select higher efficiency motors

Specifying higher efficiency motors for new and replacement applications will save money, the small additional price premium usually paying for itself in less than two years. For higher duty motors, look out for best in class efficiency motors (at least IE4).


2. Install variable speed drives

If the load being driven by your motor has a varying demand then a variable speed drive could save energy. A small speed reduction can lead to substantial reductions in energy use. The most common applications are to control flow rates in fan or pump systems, as an alternative to using dampers or valves.

See the difference a variable speed drive makes, in this short video of a typical installation.

3. Switch off

Because motors are hidden within machinery, they're often forgotten, and left running when they're not in use. Save energy by identifying and turning off motors that are left running whilst doing no productive work. This could occur during breaks, between batches or job changes, or out of normal working / production hours.

  • Implement automatic switch off controls or manual switch off procedures.
  • Consider time switches, interlocks, sensors, and intelligent controls to implement automatic Stop - Start control.

4. Monitor output

'You can't control what you can't measure' is true of most things in business. Measuring a motor's output, and monitoring trends, will help you identify areas where you could save energy. Where output changes unexpectedly, investigation may identify simple maintenance issues or a potentially serious problem.

The equipment below could help you measure and manage output:

  • Hours-run meter: measures how long equipment has been running.
  • Clip-on ammeter: can be used to measure a motor's load.
  • Portable power logging device: recommended when investment into new equipment is planned (it can provide an accurate picture of energy consumption over a pre-defined time period).
  • Permanent kWh metering: suited to large motors for measuring on-going power consumption and trend analysis.

Important note: The cost of equipment like this is likely to be paid back by energy savings made through identification of inefficiencies.


5. Have a motor management policy

Having a structured approach to repair and maintenance can save energy and reduce down-time caused by motor failure. Include in your policy:

  • a plan for repairing failed motors, which compares long-term repair vs. replacement costs
  • a plan for replacement with new and more efficient motors
  • a schedule and procedure for motor maintenance


Further guidance

We have the following motors and drives publications available for free download:


Energy efficiency support

The Carbon Trust Green Business Fund offers energy efficiency support and energy assessments for small and medium-sized businesses in England, Scotland and Wales.

If you'd like to improve energy efficiency of your organisation, see our services for small to medium enterprises to find out how we can help.

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