Hypermiling for your electric motor
2022-09-29 5 min read
It’s the middle of Summer and you are sitting in traffic. It’s so hot that the tarmac is melting on the road. The traffic begins to roll, and you start to pull away. But how do you stay cool? Open the window or crank up the air-con?
Hypermiling, or the technique of driving your car so that you use as little fuel as possible, has never been more popular. The massive increases in the wholesale price of crude oil over the last few years, combined with the war in the Ukraine and the lasting impact of COVID-19 on the global supply chain, means that forecourt petrol prices have reached new levels.
But it’s not only your car that is more expensive to run due to rocketing energy costs. It’s predicted that the 20p per kilowatt hour (kWh) price that a typical SME manufacturer has used as its benchmark for negotiation over the last year or so will soon reach a shocking 60p per kWh.
As a result, energy saving in manufacturing has never been more important; in fact, it’s no exaggeration to say that it could be the difference between life and death for many businesses. There are anecdotal reports of ceramics companies calculating that it simply isn’t worth them firing up their kilns until energy becomes less expensive.
What can you do?
It’s generally understood that electric motors and pumps, including those in general industry, compressors and ventilation, use nearly half of the world’s electricity. In 2016, the Energy Research Centre of the Netherlands (ECN) estimated that this number was 45 per cent. Meanwhile, the late pump pioneer, Professor Bernd Stoffel, estimated the global figure to be between 43 and 46 per cent in his influential paper, The Role of Pumps for Energy Consumption and Energy Saving.
So, there is no question that more efficient electric motor use can be an effective way of saving energy. Furthermore, making the motor itself last for as long as possible, while running efficiently, can both save energy, reduce capital expenditure on replacement motors and, as a result, reduce the carbon emitted during manufacture and decrease demand for rare earth materials such as neodymium and dysprosium used in production.
Fit an inverter or soft start
The best way of making anything run more efficiently is to use it less. So, if you have a variable speed application, controlling motor speed is the best way to hypermile your electric motor. The alternative is the equivalent of trying to use less petrol by putting your foot on the accelerator and controlling your speed with a brake! The motor will wear out quickly and the energy usage will be sky high.
Limit wear and tear
The worst thing you can do to your motor is increase heat and friction above necessary levels, so lubricant will always be your friend. Select the right viscosity, ensure it is free of dirt and contaminant and change it when required. This will reduce bearing wear and lengthen the motor’s effective lifespan.
Check voltage, temperature, and vibration
Ensure the application is adequately ventilated, so the motor’s temperature doesn’t raise unnecessarily. This should be double-checked during regular cleaning and maintenance.
A systems integrator or machine builder will rarely build an application without sufficient venting, but it’s very common for that venting to become inadequate during use — because debris, dust and dirt builds up and clogs the device.
Excess voltage can turn your motor into an oven, faster than you can say ‘massive cost of downtime’. So, use an oscilloscope to check for voltage imbalance and variation and use a power quality or harmonics analyser to check for harmful harmonics. Megger, Fluke and Chauvin Arnoux, amongst many others, manufacture these and they are easily available, often on next day delivery.
Power filters and surge suppression can also be used, to reduce the damage to circuitry and equipment. However, something that is less well known is that frequency attenuation can be an effective alternative, or complement to, voltage-actuated surge protection, to reduce damage caused by transients.
This type of protection actively tracks and follows the sinewave form very closely, allowing the protection device to react much faster and more effectively to remove unwanted energy. The entire sinewave form is fully protected, rather than just protecting above the extreme levels encountered in surge protection.
As well as increased temperature, increased vibration through the motor mounting can create significant problems and reduce the device’s useful lifespan. Excessive vibration leads easily to increased bearing wear and improper load distribution. To avoid this, check for misaligned mounting and ensure the fixings are tight and secure.
If you actively combine these measures, you will find that your carbon emissions, electricity bills, capital equipment costs and downtime are all reduced to much more manageable levels.
And, if you just wanted to find out whether to turn the air-con on or open the window in your car, the answer is all to do with drag. Once you get above about thirty miles an hour, the drag created by the open window will cause you to use more fuel than the air condition consumes in running. So, under 30mph crack the window, over 30mph, turn on the air con.