35 www.drivesncontrols.com September 2024 ENERGY EFFICIENCY n The other important factor to bear in mind is that there are now more options available for older motors than ever before. Repairing or rewinding an old motor if it fails will cost a fraction of what it would to replace it, and can be far more economical from a TCO perspective. There’s also an additional option in the form of refurbishment, which also includes rewinding and improving other elements. In terms of cost, this typically occupies the middle ground between repairing and replacing, and will return a motor to its original condition – or better. However, even a refurbished IE2 motor is still an IE2 motor. Take advice from your service provider as they should be transparent and offer you the options to best suit your application needs. Predetermined plan If the motor is highly specialised then it may be difficult to find a suitable replacement, and it may also take some time to arrive. Motors that are critical to operations or are difficult to access might not be straightforward to replace, and a predetermined plan should be in place in the event of a failure. Motors with low operating hours may not be running for long enough periods to make a substantial difference to energy usage. For older, less efficient motors, in particular, upgrading from, for instance, IE3 to IE5, can offer a vast improvement in efficiency and performance. IE5 motors have energy losses that are around 40% lower than IE3 motors, and the payback time for selecting an IE5 motor instead of an IE3 machine is often less than one year. Higher efficiency means increased profitability. In a typical application, an IE5 SynRM motor could save 16,730kWh per year, which equates to around 3,881kg of CO2. Each application is different, and the “sweet spot” where replacing becomes the more compelling option can vary according to the application. In addition, comparing datasheets at nominal power ratings won’t necessarily provide a true picture of how efficient a motor will be in situ. For instance, motor DOL (direct-on-line) efficiencies are typically reported on a pure sine wave, when realistically no UK industrial facility will have a power supply with a pure sine wave to start with. Reactive power levels can also increase line current and power losses in actual operation. Unfortunately, there’s no rigid formula to tell you when to repair, replace or refurbish, because the answer is invariably: “it depends”. However, if you’re using a reputable, manufacturer-approved service provider then they will be able to provide an honest assessment of the options available. Lifecycle assessment services can also help to take a lot of the jeopardy out of a sudden failure, because in such an event you’ll already have a good idea of what the theoretical upgrade pathway is for a given asset. Motor technology may be moving quickly, but even a 10-year-old motor can still have plenty of life left in it, particularly if it’s been maintained and serviced correctly. From a motor manufacturer’s point-of-view, it makes no sense to sell someone a motor that they don’t need, particularly when motor servicing has become so much more sophisticated and effective in recent years. There may not be a hard-and-fast equation as to whether upgrading, replacing or refurbishing is the best option, but talking to your manufacturer or service provider will ensure that you agree on the best possible option and have a suitable plan in place. n Synchronous reluctance motors combine an induction motor stator with a loss-free rotor constructed from axially stacked iron laminations *Based on a motor operating for 8,760 hours per year and an energy price of £0.25/kWh, using ABB motor+VSD test data A comparison of savings possible with various motor combinations* 110kW 4-pole motor Efficiency comparison Energy reduction Annual saving With a VSD IE5: 96.8% IE4: 96.0% 8,295kWh £2,074 With a VSD IE5: 96.8% IE3: 95.2% 16,730kWh £4,183 With a VSD IE5: 96.8% IE2: 94.2% 27,475kWh £6,869 DOL IE4: 96.3% IE3: 95.4%% 9,440kWh £2,360 DOL IE4: 96.3% IE2: 94.5% 19,059kWh £4,765
RkJQdWJsaXNoZXIy MjQ0NzM=