Typically a motor costing £500 will consume over £50,000 in its lifetime. It is important to select the correct motor before purchasing. Identify the requirements and the conditions under which the machine/application to be powered by the motor will operate. Then match the motor to the application to ensure efficiency and avoid the installation of oversized motors.

Consider Using Higher Efficiency Motors (HEMs).

• HEMs can save 3–5% of their running cost on average, compared to previous designs.

• HEMs are easy to retrofit.

• The highest efficiency band motors are now labelled 'eff1', and the lower band 'eff3'. Any new motors should be at least 'eff2' and preferably 'eff 1'.

High efficiency motors can give significant cost savings if used in the right applications. Compared to a standard motor, a high efficiency model can be up to 3% more efficient. A 90kW high efficiency motor could cost £1,200 more to buy than the standard model, but will save £12,000 during a ten-year service life. The failure to fit a high efficiency motor may therefore cost the company £10,800 – a fairly hefty cost for what at the time may seem a small decision. And think of what a plant with hundreds or even thousands of motors could save.

As well as saving energy costs, high efficiency motors also save on operating costs by bringing better reliability, reduced downtime and lower maintenance costs. Lower losses give the motor a better tolerance to thermal stresses, an improved ability to handle overload conditions, better resistance to abnormal operating conditions, and higher tolerance to inconsistent and noisy voltage and current wave shapes.

If a motor is rewound, its efficiency can be reduced and the modest cost of the rewind can very soon be lost by increased energy consumption. Replacing the old motor with a new High Efficiency motor will soon repay the extra cost and go on saving energy for the life of the motor. Download our Motor Energy Payback Calculator to see how quickly the extra cost of a High Efficiency motor will be paid back.Click here to download this file  

Consider Using Variable Speed Drives (VSDs). See our section on Using Variable Speed Drives .

• Fitting VSDs will enable you to control the motor speed in order to match the speed need from the equipment it is driving.

• A 20% speed reduction can result in a power reduction of close to 50%.

• VSDs are relatively simple to install or retrofit.