A key to clear communication and interoperability is having a shared understanding of the meaning behind terms and phrases. 

The United States motor industry recognises the importance of nameplates using standardised jargon among all manufacturers and has been enforcing usage of the correct terminology for the past 90 years. Using the same terminology and education around the meaning of the terminology has paid off. Having a common motor nameplate language has helped make motors interchangeable and personnel able to correctly understand the specific features of the motor they are installing or replacing.

What are the trade-offs in oversizing a motor for your next application?

Oversizing motors for any particular application is becoming more popular, as engineers seek to provide some ‘insurance’ for a new system. Insurance against possible system failure (and resulting damage to their reputation), and insurance for unanticipated future demands on the application.

An Automation World study on oversizing has asserted that over half of engineers choose to over specify motors. It seems like a ‘no-brainer’ – put in place a motor with plenty of margin of error for rated load, and use a variable speed drive (VSD) to throttle it to meet the system’s actual power needs. Peace of mind guaranteed.

CAPIEL have released their new position paper which details the importance of a system approach to energy saving: Ecodesign Requirements for Electric Motors - Towards a System-Approach

The brochure discusses the value of matching the motor and control method to the actual application needs, and provides some interesting statistics regarding energy usage and the application of electric motors.

Notably, CAPIEL point out that 80% of electric motor applications are in reality fixed speed applications, and assert that “motor starters are the most energy-efficient solution for fixed-speed applications”.  Mistakenly using VSD control with fixed speed applications will increase energy usage. In fact, a “VSD if incorrectly fitted can result in an energy efficiency loss equivalent to twice the potential gain from IE2 to IE3”.

If you’ve spent any amount of time involved with motor control or automation you’ve undoubtedly heard the rhetoric that using a variable speed drive is the best way to save energy, no matter what the application. But is this actually the case?

The simple answer is no. The real truth of the matter is that there is a place for both variable speed and fixed speed control, with the best choice dependent upon the nature of the application.

The misuse of variable speed control can have significant costs. A variable speed drive operating a system at a fixed speed has inherent losses of 3-5%. In comparison, a bypassed soft starter running a motor properly sized for the application is effectively 100% efficient, with losses less than 0.1%. A soft starter is the most efficient electronic motor control solution for fixed speed applications.

There is a significant global effort underway to reduce energy consumption in industry by improving energy efficiency, specifically the efficiency of electric motor systems. 

The initial focus was on the efficiency of individual elements, e.g. the motor, which resulted in the IE efficiency classes for motors - IE2, IE3 etc. It is now understood that greater efficiency gains are available by considering the wider motor driven system.

In Europe, Regulation EC 640/2009 is in force, requiring specific types of motors from 0.75 kW to 375 kW to meet certain IE classes.  (Additional motor types and sizes are considered by a new regulation presently in development.)

There is often confusion about what the European legislation requires.