Industrial speed control: Are PM couplings an alternative to VFDs

Over the past two decades, power-electronic adjustment-speed, or variable-frequency, drives (VFDs) have been introduced in increasing numbers to provide a high-efficiency alternative to throttling control. However, the energy savings resulting from the introduction of VFDs are obtained at the cost of significant capital expenditure. An alternative to VFD has been sought, resulting in the development of the adjustable speed coupling system (ASCS). This early, it is not yet clear which among the two provide the best results. As always, the user must weigh the options to decide if adjustable speed is valuable, and which system, newcomer ASCS or established VFD, is more appropriate.