Variable Torque Load Example Installation

A 3 phase, 100 horsepower motor drives a water pump, supplying a plant with certain flow rates. These flow rates vary during the day requiring the motor to operate under varying loads each day. The motor was sized to drive the pump at its maximum flow rate.

The flow rate is controlled by a flow control valve, restricting flow during normal operations. There are no other speed or flow control devices being used.

Is this operation a candidate for an adjustable speed drive? Several people have suggested addition of an adjustable speed drive as a way to reduce energy costs and better match needs of the plant to the water being pumped. Let's look at each aspect of this operation in order to make a rational decision about adding a drive.

And Furthermore . . .