A) Pressing gently on the accelerator, using only as much force as is needed to maintain the desired speed
B) Pressing your foot flat to the floor, and using the brake to regulate your speed
If you answered A) then congratulations – you know how to drive a car! But did you know that most of the world’s electric motors operate using B)? If you drove your car this way then not only would you burn more fuel, you’d end up wearing out parts fairly quickly.
So why are industrial motors operating inefficiently?
Motors that operate variable loads, or in other words don’t have to be run at full power all day, often regulate their speed using a throttling arrangement. This involves the use of mechanical devices such as valves, vanes and dampers to throttle the energy flow.
However, just like controlling a car’s speed using only the brake, this is woefully inefficient and can end up costing you a fortune in wasted energy and component wear.
But there is another way. A variable-speed drive (VSD) is a device that controls the speed of the motor so that it only uses as much energy as required at any given time. With additional features such as PID loop control, the motor can be controlled more accurately to meet the needs of the application, as well as eliminating the energy wasted through mechanical throttling.
The efficiency of variable torque applications such as pumps and fans follows an equation known as the cube law. This means that for any reduction in the motor’s speed, the corresponding energy reduction is exponentially higher. In practice it means that just a small reduction in motor speed can equate to a substantial energy saving – a motor running at 80 percent speed will use only 50 percent of the energy that it would use if it were running at 100 percent speed. Extrapolate this to all the motors in your company and the savings can very quickly ramp up, with very short pay-back times.
As an ABB AVP (Authorised Value Provider), we can come to your business and perform what we call an Energy Assessment. This involves using our tools and expertise to assess the whole of your organisation, and find the processes and applications where VSD can save you money, and exactly how much.
There are AVPs based all around the UK, so click here to find your nearest one. Together with ABB I’ve also helped to produce the video below, which explains more about how you can start saving energy using variable-speed drives.
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