Energy savings: Right-sizing electric motors could save billions in energy annually

Energy efficiency losses through over-sizing of pump electric motors by engineers are commonplace, according to WEG Electric Motors.


Atlanta, GA — “Industry figures suggest that around 80% of pump motors could be the incorrect size,” commented Andrew Glover, product manager for WEG Electric Motors , a global supplier of motors, drives, controls, generators, and transformers. “The majority are over specified by as much as 10 or 15% by engineers wanting to be‘on the safe side.’ As pumps typically account for around 30% of an industrial country’s energy usage, this represents a serious loss of energy. Electric motor manufacturers are forever striving to increase energy efficiency by one or two percentage points, but incorrect specificationby an application engineer can mean that is wasted effort.”
Glover explains that his figures take no account for the extra cost of a larger motor with all the associated equipment, drives, cabling, etc. “A single percentage point increase in energy efficiency,” he says, “can save the equivalent of the purchase price of an electric motor over its design life, it seems ludicrous to waste energy through poor specification.”
Glover’s research indicates that under-sizing is also relatively common and should not be ignored. An electric motor can operate above its rated output, thus allowing for temporary overloads. However, such a motor will run hotter as a result, and overheating will cause damage and/or shorten its useful life. Two points where this can directly affect the motor life are the bearings, which influence the motor reliability, and the coil insulation. Overheating degrades the insulation more rapidly and encourages discharges, which further degrade the insulation, thus shortening the motor’s life.
Specification of motor size should, therefore, include starting condition as well as running torque. Method of starting is also important; direct on line starting methods will create high torque that also impose mechanical stresses on the pump and hydraulic components, while star delta starting delivers lower torque and current.
Glover suggests including a variable speed drive or soft starter in the system specification, matched to the requirements of motor and pump will easily overcome these problems. Variable speed drives also improve energy efficiency in the long term by matching application requirements with the correct motor speed and thus avoid energy wasted by, for example, belt drives, clutches and gears.
— Edited by C.G. Masi , senior editor
Control Engineering Machine Control eNewsletter
Register here and scroll down to select your choice of eNewsletters free.

No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Choosing controllers: PLCs, PACs, IPCs, DCS? What's best for your application?; Wireless trends; Design, integration; Manufacturing Day; Product Exclusive
Variable speed drives: Smooth, efficient, electrically quite motion control; Process control upgrades; Mobile intelligence; Product finalists: Vote now; Product Exclusives
Machine design tips: Pneumatic or electric; Software upgrades; Ethernet advantages; Additive manufacturing; Engineering Leaders; Product exclusives: PLC, HMI, IO
This article collection contains the 5 most referenced articles on improving the use of PID.
Learn how Industry 4.0 adds supply chain efficiency, optimizes pricing, improves quality, and more.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Cyber security cost-efficient for industrial control systems; Extracting full value from operational data; Managing cyber security risks
Drilling for Big Data: Managing the flow of information; Big data drilldown series: Challenge and opportunity; OT to IT: Creating a circle of improvement; Industry loses best workers, again
Pipeline vulnerabilities? Securing hydrocarbon transit; Predictive analytics hit the mainstream; Dirty pipelines decrease flow, production—pig your line; Ensuring pipeline physical and cyber security