Tero Helpio, Global Product Manager, IEC Low voltage motors, ABB, explains how IE5 synchronous reluctance motors and variable speed drive packages can improve the energy efficiency of heating, ventilation and air-conditioning (HVAC) systems to help our cities reach their sustainability targets.
HVAC systems worldwide rely on millions of low-voltage (LV) electric motors to run pumps, fans and compressors. However, there is a price to pay in terms of energy consumption and associated CO2 emissions. These motors consume on average about 50% of the energy used in buildings.
Systems to control different processes inside buildings have existed for decades. However, they were not energy efficient. The development of variable speed drive (VSD) technology has made it possible to solve many of the inefficiencies in buildings. Because HVAC systems run at partial loads close to 99% of the time, VSDs can save energy by an average of 20 to 60% compared to traditional damper or valve control methods. Such massive energy savings are possible because drives can adjust the motor speed of equipment directly to meet the current building needs. Variable speed control delivers the full benefit of running HVAC applications at partial load, allowing accurate control of ambient CO₂ levels, temperature, and humidity for the best indoor air quality and occupant comfort, health and safety, while optimising energy use.
More efficient motor technologies
Variable speed drives help save a lot of energy. However, operators can enhance the savings with only a small investment in technology. Most of the motors in our buildings today are only efficiency class IE1 or IE2. Upgrading the motors to IE5 synchronous reluctance motors (SynRM) offers substantially more energy savings. Compared to even an IE3 energy efficiency class induction motor, it offers up to 40% reduced energy losses, delivering ultra-premium energy efficiency – a new level of efficiency defined by the International Electrotechnical Commission (IEC). This attribute makes SynRMs the first choice to meet the growing global demand for improved energy efficiency.
We have already noted that buildings operate most of the time at partial loads. Therefore, it’s important to consider a motor’s partial load performance instead of just the nominal performance. A SynRM IE5 motor at partial load offers even more significant advantages over other motor technologies. Synchronous reluctance technology combines the performance of permanent magnet motors with the simplicity and service-friendliness of induction motors. The rotor in a synchronous reluctance motor has no magnets or windings and suffers virtually no power losses. It also requires less material for manufacturing than a traditional motor – a great bonus for sustainability.
Fast deployment for quick ROI
A SynRM motor always combines with a VSD to create an optimised package and retrofit. The motor is a drop-in replacement, as the form factor is identical to existing IEC motors. A wide range of VSDs are currently programmed to work with these motors, and extensive testing has been conducted with ABB’s VSDs. These drives feature the latest custom-designed software for pinpoint control. The versatility and accuracy of both motor and VSD ensure exceptional speed stability. Accurate control at low speeds maintains optimal torque without tripping, optimising energy use.
A motor’s purchase price constitutes a minor portion of its lifetime cost – the main expenditure is in the energy it uses. Investing in a VSD and SynRM IE5 motor package will deliver fast payback in energy savings alone.
Whereas the initial cost of a SynRM IE5 motor will initially outweigh that of an IE3 motor and VSD package, its energy-saving capability will rapidly make up the difference, often within 12 months. Subsequent savings will continue for at least 10 years or more. HVAC systems across the world will undoubtedly benefit by upgrading to the ultra-premium efficiency of IE5 motors with VSD control.
This video illustrates the benefits of using a VSD and SynRM motor: https://www.youtube.com/watch?v=bMreUqVP4Bk&t=17s