The system can be applied to multi-pump or -fan applications where system flow or pressure can be satisfied by a combination of constant- and variable-speed operation.

Special motor-sequencing software enables a single vfd to operate one of several ac motors at variable speed in response to system demand, the company explains. When demand exceeds the capacity of the first pump or fan, the multiplexer transfers the motor from vfd power to ac line power. The vfd then starts the next motor to operate at variable speed.

The traditional approach to achieving speed control on multiple motor systems has been to install vfd’s on each motor, or one very large vfd sized to handle all the motors. Either approach can be costly, says MagneTek. The multiplexing system makes it possible to use a single vfd equal to the size of the largest motor in the system to achieve variable response to system demand.

For more information, call 800-541-0939.