Saving money with energy efficient motors

Assessing your motors and drives


The power used by electric motors accounts for nearly two-thirds of the electricity consumed by industry in the UK and is responsible for a significant volume of CO2 emissions. Even a small or medium sized business could have hundreds of electric motors on site.

The cost of running an electric motor is often underestimated. In a single year the cost of the energy needed to run a motor can be as much as ten times its purchase cost. Typically, the annual cost of running a small motor rated at 2.2 kilowatts is around £800, rising to around £14,000 for a motor rated at 37 kilowatts, depending on electricity costs. With running costs this high, it is important to introduce cost-saving measures wherever possible.

Understanding electric motors

An electric motor is a device that converts electrical energy into rotary kinetic energy that is used to power a particular process.

There are several different types of motor, all of which have different characteristics, advantages and uses. The most commonly used motor is the induction motor. This uses conventional alternating electric current to induce a force on its rotor, causing it to rotate.

Ordinary induction motors usually run at a single fixed speed. But a variable speed drive can be used that controls the electrical supply to an induction motor, allowing it to run at different speeds. Other types of motor, such as multiple speed motors, can run at between two and four different speeds.

Cost savings on electric motors

Electric motors are used to drive many items of machinery such as pumps, fans, conveyor belts and compressors. To make cost savings you need to look at the whole process, not just the motor itself, otherwise you could overlook ways to make significant and often inexpensive cost reductions.