Using variable speed drives (VSDs) to control industrial electric motors can be a game-changing green option. For even better results, pairing a drive with the latest IE5 SynRM motor technology will take energy efficiency to the next level.
In November 2021, the 26th UN Climate Change Conference of the Parties (COP26) saw many nations around the world committing to cut carbon emissions by 2030 and achieve Net Zero by 2050. A key step will be the delivery of sustainable industrial systems and the promotion of clean renewable energy. Also playing a vital role will be the broader adoption of energy efficient technology. This is so important that the International Energy Authority (IEA) regards it as the “first fuel” in tackling climate change.
The IEA has published compelling figures showing that adopting energy efficiency measures will allow the world economy to grow 40% by 2030, while using 7% less energy than it does today. Electric motors are one area where technology can really make a difference. They are used widely in industry, running water treatment plants, refrigerating food, ventilating buildings, operating materials handling systems and so on. However, many of the estimated 300 million industrial electric motor-driven systems currently in use are inefficient and waste too much energy.
The good news is that the vast majority of industrial motors run pumps, fans, and compressors, all applications that are very amenable to major efficiency improvements. One technology that can make a major difference is the use of VSDs, as typically they can cut energy consumption by a quarter.
VSDs are already making a significant contribution to industry, but they could do more. Current estimates indicate that just 23% of the world’s industrial motors are controlled by a VSD. That level is expected to increase to 26% over the next five years. Even so, faster adoption will deliver substantial additional savings because roughly half of all industrial motors would benefit from being paired with a drive.
How does a VSD deliver energy savings?
A VSD controls an electric motor to optimize its operation to match the application. That means it adjusts the speed and torque of the motor to suit the exact requirements of the process. Because the electric motor only runs as fast as is it actually needed, significant energy savings are possible.
To control the speed of an AC motor, the drive varies the frequency and voltage of its power supply. Recent advances in power electronics have made drives both less expensive and significantly more sophisticated in their capabilities.
Despite these recent strides, the deployment of VSDs has so far progressed only at a modest pace. That means there is significant scope for industry to gain major energy efficient benefits by using drives on a broader basis. That is because when a motor is not controlled by a drive, it is generally running at full speed even when the load requirements are minimal.
For example, to control the flow of water or other liquids in pumping applications, throttling is often used. That is much the same as trying to reduce the speed of a car by applying the brakes without letting up on the accelerator. It is simply a waste of energy. In addition, the relationship between motor speed and energy consumption is non-linear. Therefore, only a small incremental reduction in speed will deliver significant energy savings. For example, slowing a fan or pump motor by 20% can save as much as 50% on energy use.
VSD technology is crucial to the success of SynRM motors
VSDs will help save energy in almost any process that requires a change from full speed operation, and especially pumps and fans. The story does not end there. Since partnering a drive with the new generation of synchronous reluctance (SynRM) motors, has the potential to achieve exceptional levels of efficiency.
The first SynRM motors appeared as long ago as 1923, although they need to be matched with a VSD to work correctly. It is only in the last decade or so that advanced VSD technology has been able to unlock their full advantages.
ABB is now supplying SynRM motor and drive packages compliant with the IE5 ultra-premium rating. This goes well beyond the new minimum standard, IE3, for International Efficiency (IE) classes for low-voltage motors, established and enforced by the EU Ecodesign Regulation in July 2021.
The exact savings made possible by this leap in energy efficiency depend on the application and conditions. However, when an IE3 induction motor is paired with a VSD energy bills are reduced typically by up to 25%. In addition, a further saving of around 3-4% is possible when an IE3 and VSD combination is replaced by an IE5 SynRM-Drive package.
As well as improving energy efficiency, a SynRM and VSD package provides reliable performance, low maintenance costs and more. It is also easy to retrofit into existing installations, or incorporate into new projects and OEM designs, and offers plug-and-play simplicity.
Most industrial motors in the current installed base date back at least 10 years, to a time when designs were much less efficient. If they were replaced with optimized, high-efficiency equipment, global electricity consumption could be reduced by up to 10 percent, with a consequent reduction in CO2 emissions.
Easy to deploy for a fast return on investment
VSDs are ready to go. Users can simply plug, play, and instantly reduce their carbon footprint. At the same time SynRM motors slot easily into industry standard frames designed for their induction motor predecessors, with no need for mechanical modifications.
The investment in upgrading to a VSD and SynRM IE5 motor package is easy to justify in terms of energy savings alone. This is because the purchase price of a motor is just a small fraction of its lifetime cost. The main expenditure lies in the energy used to run it. Opting for a SynRM IE5 motor will initially cost a little more than an IE3 motor and VSD package to buy, but energy savings will quickly refund that difference – often in as little as a year. After that, the package will continue to generate annual savings over the next 10 years or more.
As an example, an ABB SynRM and VSD package has resulted in a considerable drop in energy costs at Campbell's Australia. Over a 12-month period, the numbers clearly showed a 14% reduction in energy costs. The annual saving of over $10,000 on energy bills also resulted in an annual reduction of approximately 131 tonnes of CO₂ emissions.
Mark Hyland, Environmental and Safety Manager at Campbell’s Australia,
inspecting a refrigeration compressor driven by an ABB SynRM motor and drive package.
Embrace the opportunity
Furthering the global deployment of drives and high-efficiency electric motor technology is an exciting opportunity to help the world reduce its energy usage. The savings will help the global drive to Net Zero, they will also benefit industry through reduced electricity costs and greater productivity.
