New Electric Motors Save Three Million Kwh

New electric motors save three million kWh

Being awarded by the German corporate initiative DENEFF for developing the SuPremE synchronous reluctance motor was a good opportunity for the pump and valve manufacturer KSB to once more underline the massive savings IE4 motors can make compared with today’s most commonly used IE2 asynchronous motors. Daniel Gontermann, who is responsible for high-efficiency drives at KSB, illustrates this with an example calculation:

The efficiency of a 7.5kW SuPremE motor operated at full speed and full load already exceeds that of an equivalent IE2 motor by up to 4%. At a quarter of the speed, and consequentially 25% of the flow rate, this advantage can be as high as 24% (see table).

Flow rate / 100 % / 75 % / 50 % / 25 %
Efficiency IE2 motor (**) / 88.1 % / 85.2 % / 77.5 % / 39.2 %
Efficiency SuPremE(*) / 92.1 %* / 91.2 %* / 87.8 % / 63.2 %
Time in % / 6 % / 15 % / 35 % / 44 %

Using a single motor of this rating will save circulator operators 1,380kWh per year, for example. At the same time, the pump set will emit 815kg less CO2 per year than a variable speed pump with IE2 asynchronous motor. The calculation of operating time percentages is based on the typical load profile for this application in accordance with the “Blue Angel” environmental requirements. At an energy price of 15cent/kWh the annual savings per motor equal € 207.

As the pump manufacturer sells the IE4 motor up to 18.5 kW in combination with its Etaline pump without a surcharge, investing in a SuPremE motor pays from day one. The additional savings made by variable speed compared with fixed speed pumps have not been taken into account in the above calculations. The 7.5kW motor is a good example as it is close to the mean values of the type series overall; it is presently also the most popular motor at 19% of the quantity sold.

If we were to calculate the savings of all IE4 motors manufactured by KSB so far, we would look at about 3millionkWh. This equals a reduction in CO2 emissions of 1,600 tonnes.

*(To RAL Standard UZ105 "Blue Angel" for circulators, applicable from February2007)

** The comparison shown is based on an approximation model using measured data. It compares synchronous reluctance motors of the KSB SuPremE series with common asynchronous motors. The efficiency classes mentioned are in accordance with IEC60034-30. The efficiency tolerance at the nominal operating point is in accordance with IEC 60034-1. At all other operating points, the tolerance equals +/- 10 % of the nominal value. These data are only valid for operation controlled by a KSB PumpDrive (S) variable speed system in moderate thermal conditions. Losses in the motor caused by frequency inverter control have already been taken into account in the efficiencies indicated. The control concept for the synchronous motor is a vector-oriented concept with active flow control; that of the asynchronous motor is a U/f² control concept optimised for quadratic loads. The carrier frequency is assumed to be constant at 4kHz.