What is air compressor electric motor efficiency?

As part of a concerted effort worldwide to reduce energy consumption, CO2 emissions and the impact of industrial operations on the environment, regulatory authorities in many countries have introduced legislation to encourage the manufacture and use of higher efficiency electric motors. We're proud to supply Chicago Pneumatic, who have not only taken these efficiency considerations on board but has gone even further to achieve the highest efficiency class – equivalent to IE5 - in its compressor technology

When it comes to compressor drive motors there is a close correlation between the electric motor technologies and their efficiency level capabilities. Firstly, single phase induction motors are limited to levels IE1 and IE2, whereas three-phase induction and switched reluctance synchronous motors can meet the IE1, IE2, IE3 and in some cases IE4 category criteria.

The introduction of permanent magnet (PM) motors has increased the opportunities of achieving IE4 and IE5.

With AC induction motors operating within the 90%-plus efficiency band for most power ratings, there may not be much more room for the development of this type of motor to produce higher energy efficiencies.

This is where alternative motor designs such as permanent magnet (PM) rotor technology come in. Unlike induction motors, which induce a secondary magnetic field in the rotor, PM motors use high-performance magnets attached to the external surface of the rotor to create a magnetic field that is always present. This eliminates the rotor losses found in the induction-motor design, resulting in higher efficiency and a better power factor.

However, by going beyond the PM motor, it’s possible to take greater steps toward meeting or even exceeding the IE5 standard. This has been made achievable with the introduction of the iPM (interior permanent magnet) motor concept.

A conventional PM motor, or SPM (surface permanent magnet) to be precise, only uses magnetic torque to operate. Although this technology overcomes rotor losses, it imposes speed limitations due to the need to secure the rotating magnets and reduce the risk of them being peeled off by centrifugal force.

The advantages of the iPM motor

The IPM motor with its embedded permanent magnets rotor does not have this problem. It can operate at higher speeds, enabling direct coupling to the compression element on a 1:1 ratio and, as a direct result has up to 30% lower losses compared to conventional motors.

Promoting high efficiency

There are other specific features relating to the motor that contribute to the overall efficiency of the compressor, including true direct drive. If the rotor of the motor is coupled directly to the male rotor of the compressor element, there are no drive losses associated with gears or belts and no shaft seal.

Equally, if the motor is cooled by the compressor oil, which is effective at all running speeds, there is no need for a cooling fan that consumes power and reduces motor efficiency. This is especially evident when the motor is running at a low speed. The oil cooling the motor warms the lubricating oil before it reaches the compressor element and helps prevent condensation under low load conditions.

The high torque capability of an iPM motor allows the compressor to start whilst still pressurized, hence there is no need to blowdown the compressor when it stops in standby mode. As a result, air that has already been compressed, and for which the user has paid for in energy consumption, is not wasted.

Conventionally designed compressor motors have two bearings, one for the element drive end and another for the non-drive end. If the drive end is supported on the compression element bearings, the motor only needs one bearing, resulting in a significant reduction in friction losses.

Who we are and how Ash Air can help your business!

Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a reputation for quality and reliability.We look after all things compressed air for your business!

Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.

Reliability and Efficiency

With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our efforts on the following:


Talk to the team today:  CONTACT US CONTACT US


Other Blogs


Just like any other equipment, a compressed air installation also requires the necessary maintenance work during its entire lifespan. Even though maintenance costs are only about 5 to 10% of a machine's annual operating costs, failure to budget for maintenance can have potentially disastrous consequences. …


The air dyer is one of the most ignored cooler in the system. A dirty condenser will cause water in the lines, or worse it will cause complete dryer failure. …


Using nitrogen is not about fully replacing CO2, but it can reduce their consumption of CO2 by close to 70%. Using nitrogen is about sustainability. Creating your own nitrogen is easy and will reduce the use of a greenhouse gas, which is better for the environment. It will also save you money as early as month one adding that savings to your bottom line. …


A question that is occasionally asked by our customers to Ash Air is 'what is the cost of compressed air?'Β  This article looks at the product costs involved with compressed air, as well as minimising the energy cost of compressors and cost allocation. When looking at these factors, we need to realise what causes dropped efficiency of your compressor, leading to increased costs of compressed air. …


You may have great fall protection measures in place to keep employees safe when working at height, but what about their co-workers below? Dropped tools and other falling objects are a major hazard – and one that isn’t always fully addressed.Β  …


Providing a safe working environment for operators is essential, especially when using pneumatic tools and compressed air. If there is a failure in the air network and the hose is not adequately clamped, the resulting whiplash could be devastating. Failure to follow best practice can result in injuries, associated production downtime and decreased productivity. …

Show More