Variable Frequency Drive

Variable frequency drive (VFD) is a technology to control electrical motors instead of direct connection, wye-delta or soft starter. The most typical application is in the control of induction motors, but VFD can also be used with other electrical motors. The main benefit of using VFD is that it allows motor speed adjustment almost completely freely. This enables the electric motor to be used directly in process controlling without additional control devices (e.g. water flow or hydraulic motor speed control) as well as controlled slowing and acceleration with mechanical equipment. Furthermore, it is possible to achieve significant energy savings with VFD, especially in process controlling.

Equipment and system principle

A variable frequency drive system consists of the VFD itself and its related control system. StrongFlow uses mainly Schneider Electric’s VFDs. With simple solutions, it is possible to use integrated controls typically included in the VFD unit, whereas with more complex systems an external automation control system is required.

Required information for system design

A variable frequency drive system design is based on the requirements of the process/equipment to be controlled. The best starting point for defining an offer and design is a functional description which includes the required functionality of the equipment/process, applied motors and other possible actuators. Furthermore, information about the power supply is needed (supply voltage and frequency).