0262 1762/05 © 2005 Elsevier Ltd. All rights reserved WORLD PUMPS January 200532

The simplest and most fruitfulapproach to reducing therunning costs of pumping

operations can be summed up in justfour words - invest in quality motors.First, paying a bit extra up front forenergy-efficient, reliable motors will cutenergy bills. This is no mean feat whenthe US-based Hydraulic Institutesuggests that 90 % of the total cost ofowning of a pump lies in the energy itconsumes over its lifetime. Furthermore,there are fundamental reasons whyhigh-quality, energy-efficient motorstend to be more reliable, reducing theneed for expensive repairs and thepotentially huge expense of downtime.

The right choice

The trick is not to be tempted by so-called bargains. Some motors withsimilar specifications can cost twice asmuch as others. But motors normallyconsume their own capital cost inenergy after just 30 days of continuousoperation, in which case the initial

purchase price soon pales incomparison to the running costs.Cheap motors are normally lessefficient, so they produce more wasteheat and all that energy ends up on theelectricity bill of the end user.

The European Union has introducedlabelling to make it easier than ever tomake an energy-efficient choice. ForAC motors between 1.1 and 90kW, theEU now requires manufacturers to labelmotors according to efficiency. Thelabels run from EFF3 (the leastefficient) to EFF1 (the most efficient).

The difference in the energy efficiencyoffered by two motors may seem slight,but even a few percentage points willsoon add up. The difference inefficiency between a high-efficiencyEFF1 motor and a standard EFF2 motorcan be as much as six per cent. This canoffset the additional cost of an EFF1motor compared to an EFF2 motor inless than 12 months of continuousoperation and will continue to savemoney over its operational life.

The main reason that it is the moreexpensive motors that tend to be moreenergy efficient is that 55 per cent ofthe cost of a motor lies in the materials.This means that it is not possible tomake significantly cheaper motors justby cutting back on sales, marketing ordistribution - a cheaper motor istypically going to be built from cheaper,lower quality materials. Today's marketfor motors is very competitive, so theopposite also holds true: Amanufacturer of more expensivemotors won't last long withoutproviding a genuinely superior product.

Cheaper motors are less durable,typically falling way short of the 20years possible life expectancy withhigh-quality versions. Some mightargue that if you could buy a motor

cheaply enough you could replace itmore often and still be better off. Butthe cost of downtime soon surpassesany initial savings. Indeed, downtimecosts many companies as much as a newmotor every five minutes.

A case in point

For example, Imerys Minerals inCornwall has entered an agreementwith ABB to supply motors and drives toits UK plants in a bid to save downtimecosts of up to £10,000 per hour.

Extraction and processing is a 24/7continuous process, using high pressurewater systems in the quarries. Imerys isthe largest user of motors in the SouthWest, employing more than 5,000motors and over 27 MW of installedpower driving pumps and handlingsystems for the extraction of 2 milliontonnes of china clay per annum. Thecompany makes extensive use ofcondition monitoring and failure modeanalysis since any motor failure canlead to extended downtime.

Quality and delivery problems fromtheir previous suppliers promptedImerys to look for a new supplier ofmotors and drives. ABB motors anddrives were ultimately selected on thebasis of mechanical build quality,reliability and energy efficiency.

Dave Constance, Electrical Managerfor Imerys, says: "In our experience ofrunning motors we have never comeacross a motor as reliable as these fromABB. They are well designed for theharsh environment we work in, withbetter protection against ingress of dustand water and improved cooling. Thedrives work well in the wet and harshenvironment found in our quarries andare well protected against ingress ofwater or slurry, which could otherwisecause expensive damage and downtime.

Motors to reduce running costsMotors significant part in the running costs of any pump system. Not only do motors rack upenergy costs, downtime and repairs can all add to the final bill. Steve Ruddell, generalmanager drives & motors ABB Limited looks at the differences between energy efficientmotors, as labelled by the EU, and argues the case for paying for quality.

f e a t u r e r e d u c i n g r u n n i n g c o s t s

Figure 1. 55%of thecost of a motor lies inthe materials - that'swhy it is the moreexpensive motorsthat tend to be moreefficient and reliable

WORLD PUMPS January 2005 www.worldpumps.com 33

f e a t u r e r e d u c i n g r u n n i n g c o s t s

"We didn't take what we were told atface value. We examined motors anddrives from a number of manufacturersand conducted compatibility tests tosee if they were suitable for ourenvironment. We stripped the motorsdown to look at how easy they were tomaintain and how this would affect therunning costs. Efficiency tests were alsoan important part of our investigation.For all criteria, ABB came out on top."

Lifetime cost of ownership is importantto Imerys and so getting the maximumtime between maintenance sessions wasvital. The company made suggestions toimprove the sealing on a motor bearingto reduce its maintenance needs andABB altered the design of a casting toaccommodate this as part of its policy ofcontinuous improvement based uponcustomer feedback.

Reliability

There is a more fundamental reasonwhy lower quality motors are lessreliable however. The extra energythat inefficient motors waste istransformed into waste heat, whichcan cause long-term damage to themotor itself. In the worst cases,temperatures as high as 140°C on thehousing surface (compared to approx.80°C for a high-quality, energy-efficient motor) have been measuredunder normal running conditions.That can damage both theimpregnation on the motor windingsand also the lubricants that protectthe bearings.

Reducing the winding temperatureunder normal running by between 5 and10°C can equate to a 50% extension ofthe winding life. By reducing thebearing temperature by just 10°C,cooler running motors can also extendre-greasing intervals by 50%. Sincemotor malfunctions are usually causedby the failure of either the winding orthe bearings, these changes significantlyimprove overall reliability.

Help with motor management isavailable through the EU's MotorChallenge Programme, which waslaunched early last year. MCP is one of

a series of energy-saving initiativesunder the European climate changeprogramme.

End user companies can participate inMCP by applying to become 'Partners',while sympathetic manufacturers ofmotor-driven systems can become'Endorsers'.

Challenge Partners receive help indefining and implementing an actionplan to reduce energy-related operatingexpenses without compromisingreliability and quality of service.

As well reaping energy savings thatshould provide an immediate boost toprofits, adopting an MCP Action Plancan provide Partners with a vehicle tohighlight their responsible greencredentials. MCP can provide publicitythrough its various publications andPartners can use the eye-catching MCPlogo in their own literature.

The stakes for European industry arehigh. Motor-driven systems account for30 % of all the electricity consumed inthe European Union and for 60% ofindustrial consumption. So it's nosurprise that adding just a fewpercentage points of motor efficiencycan have a major impact on acompany's bottom line.

It has been estimated by MCP officials,for example, that replacing all the EFF3motors now in use across Europe withEFF2 versions would yield energysavings of 6TWh, or Euros 300m a year.

Such huge savings won't come fromnowhere, however. They will only bepossible thanks to individualcompanies taking the decision to basetheir motor choices on life-cycle costsrather than cheap deals up front.

OEMs also have an important role toplay. They have a lot to lose if they optfor less reliable motors in pumpingequipment. After all, it's the OEMthat gets the blame when theirproduct fails, not the motormanufacturer. ■

ABB Motor Service Partners:http://www.abbmsp.co.ukThe Motor Challenge Programme: http://www.cda.org.uk/news/motorchallenge.htmhttp://energyefficiency.jrc.cec.eu.int/motorchallenge

CONTACTSteve RuddellGeneral Manager Drives & MotorsABB Limited, 9 The TowersWilmslow Road, DidsburyManchester, M20 2ABTel: 0161 438 3204Fax: 0161 448 1066Email: enquiries@gb.abb.com; Web: www.abb.com/motors&drives

Figure 2. ImerysMinerals in Cornwall

uses quality motorsfor its high pressure

pumpingapplications, aimingto avoid downtime

costs of up to £10,000per hour