How useful are Motor Selection Tools?

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Answer by Hugh Falkner

Simple on-line motor saving calculators are available from many suppliers, giving a quick way of calculating the energy and cost savings from fitting a new high efficiency motor in place of a less efficient motor.  The simplicity of the tools is a big attraction, but do check that any defaults such as motor price, electricity price, running hours and load factor are realistic.

While they are useful, it can become time consuming to use them for every purchasing decision.  Most users soon find that after evaluating several options there is no need to use a Selection Tool, as the results for most scenarios will point to the use of the same motor efficiency level.  This reflects normal purchasing practice, where a company will set up a framework contract with one or maybe two suppliers for particular ranges of motors.

Throughout the 1990s and 2000s, there was wide promotion of the use of motor databases that would identify the most cost effective option for each motor application on a site.  However, the use of these has now declined such that the list of motors is often out of date, and the software itself may not be supported.  Various reasons can be suggested for this, but the main reason must be that with increasingly stringent Minimum Energy Performance (MEPS) levels for motors worldwide, there is far less variation in the efficiency of available motors.  For example, with IE3 shortly to become the MEPS in Europe, and IE4 motors only justifiable in heavier duty applications, the market will be dominated by IE3 products.   For most users there is therefore no need to consider different efficiency options.

There is a variation in the efficiency of IE3 motors, but in practical terms this is only modest, as there is little commercial benefit in selling motors with efficiencies significantly above the IE3 efficiency threshold.