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Wednesday, September 29, 2010



It is imperative that all factors are taken into consideration when calculating the potential cost saving of standard motors versus high efficiency.

Some of the factors that should be considered have been explained above as well as the

following :

Stockholding – Is the high efficiency motor range chosen by your Company a

standard stock item in all voltages and sizes that is immediately


Non-standard high efficiency motors are not held in stock unless

there is a special arrangement with customer & supplier. ( This type

of agreement generally binds the customer to one supplier. )

Price variation – Generally High Efficiency 2 motors are standard stockable items

held by most suppliers at competitive prices.

The additional cost to purchase Efficiency 1 will differ from each

supplier but is in the region of 30% to 45% above standard prices.

Dimensions - High Efficiency motor dimensions can differ from previous standard sizes. The motors will generally be longer to accommodate for larger stator cores.

Eff Standard - Customers have to rely on suppliers published performance data in respect to purchase & calculations. South Africa do not have a proper Efficiency standard that suppliers have to conform to or have their motors tested against. In a recent independent test conducted by a large corporation it is apparent that there a definitely a concerned variation between suppliers published data & actual tested data.

WEM Electric is a member of the SABS Efficiency Forum which has recently published it’s draft specification for motor efficiency.

Approved repair - Does your company have a Approved Repair Company – High

Efficiency repairs require special procedures & attention.

(Repair maintenance records and tests provide vital information for

either replacement or repair decisions.)

If no specified repair plan or procedure is in place with your approved armature winder which specifically covers the rewind or repair of a High Efficiency motor, one should then possibly spare the extra expense of purchasing a High Efficiency motor in lieu of a standard motor.

Insulation class - Generally the world standard is Class F insulation. Suppliers in South Africa normally offer Class F insulation with B temp rise.

Should you purchase a motor from a reputable supplier, correctly sized, applied and installed and it is operating under the conditions for which was designed you will have no reason to be concerned about overheating.