Pump and fan systems are variable-load applications that account for a large share of a plant's electricity consumption. Motor selection here must be based not on power alone but on how well the motor's operating point matches the flow-and-pressure curve.

Speed Selection for Pumps and Fans

In centrifugal pumps and fans, flow varies directly with speed, pressure with the square of speed, and power with the cube. For this reason 2-pole 3000 rpm motors are preferred for high-pressure pumps, 4-pole 1500 rpm motors for general water transfer, and 6-pole 1000 rpm motors for large-diameter, low-pressure fans.

Efficiency with a Frequency Converter

In variable-flow systems, adjusting speed to demand with a frequency converter saves far more energy than running the motor at full speed and throttling a valve. Because of the cubic power relationship, a 20 percent drop in speed corresponds to a much larger drop in power; this is where IE3 and IE4 motors prove their value alongside a variable speed drive.

The Scope of the 0.55 to 90 kW Range

From small circulation pumps to large ventilation fans, a wide spread falls within this power range. IP55 protection, Class F insulation and B3/B5 mounting options let the motor serve safely in both wet rooms and rooftop fan units.

DRG for Your Pump and Fan Line

DRG Motor offers motors suited to pump and fan applications from 0.55 to 90 kW, 400 V / 50 Hz, in various pole counts. Share your system's flow-pressure values and duty profile and we can help you pin down the right speed and efficiency class.