why variable speed drives?

Also known as AC drive, motor speed controller, VVVF, VFD, VSD, Varidrive or PWM Drive, the Zener Variable Speed Drive provides direct control of the speed of an electric motor whilst maintaining high levels of motor torque. Variable speed drives achieve this speed control by varying the frequency applied to the motor. Using a PWM (Pulse Width Modulated) control system the output is controlled to vary the voltage and frequency to the motor.

Process automation and productivity improvements

A Zener variable speed drive offers total control of motor speed without sacrificing torque. The speed can be controlled locally (manually), remotely or automatically using internal or external controls. The optimum speed for a process can be adjusted quickly and easily by an operator or process controller.

Energy savings and improved resource management

A Zener variable speed drive enables a reduction in speed when operation at full power or capacity is not required. On variable torque loads such as fans and pumps a reduction in speed can result in substantial energy savings. Pumping water becomes more efficient. Energy costs and carbon footprint are reduced.

Reduced mechanical stress - motor and load

Using a Zener variable speed drive will control the rate of acceleration and deceleration and allow a perfect soft start and soft stop to be achieved. A controlled soft start will reduce the mechanical stress on the motor shaft and load. The Zener variable speed drive will also provide full torque up to the motor's rated speed.

Significantly reduce starting currents

You will significantly reduce the starting current of a motor with a Zener variable speed drive. The motor's starting current under full load will typically be below 110% FLC for a pump or fan. Compare this with 600-800% for direct-on-line (DOL) starting. Starting currents on the input (AC line) side of a Zener variable speed drive will be even lower, usually way less than full load.

Less demand on electrical supply infrastructure

The reduction in starting current and the improved power factor reduces the demand on the electrical infrastructure and can reduce the costs or need to increase site capacities.