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  • IEC 60034-31:2009

  • 27 –


8 Economy


Relevance to users

The motor user wants a reliable and cost effective motor system. Initial motor purchase cost is low compared with operating cost during the operation phase. Operating costs of electric motors are generally over 90% of the total cost of ownership (see Figure 11).

Electric Energy Cost 96,7%

Initial Capital Cost 2,3%

Repair & Maintenance Cost 1,0%

Figure 11

11 kW IE3 motor, 4000 operating hours per year, 15 year life cycle Source: EuP Lot 11, 2008

Higher efficiency motors cost more because of their higher production quality and additional material used. The additional cost depends on output size and type of motor. Between IE1 and IE2 some 10% to 15%, between IE2 and IE3 another 10% to 15% have to be added to the amount of required active materials (steel, copper). Furthermore, higher quality materials may be necessary.Therefore, the typical price increase could be between 10% to 30% per efficiency class improvement. In comparing motor efficiency not only the increase of efficiency but also the respective power factor has to be taken into account.

Both in the case of replacement and with new installations users are faced with a complex decision for the purchase because it involves the consideration of operating costs together with initial purchase cost for a variety of project possibilities. In the case of replacement also the case of repairing the motor should to be evaluated.

Two methods are generally used for the decision making:

    • Simple pay back

    • Life cycle cost

      • 8.2

        Initial purchase cost

The initial purchase cost consists of planning, installation and the purchase price of the motor and additional equipment like adjustable speed drives (minus rebates, plus taxes).

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