AC VFD Drives

Frequently, VFDs and AC induction motors are installed to replace slip-ring motors, direct-on-line (DOL) starting or soft-starters. There is not much of a price difference between a small VFD and soft-start anymore. Replacing with an VFD means that the benefits of energy savings and improved process control come as part of the package. Old soft-starters can suffer from reliability problems, particularly if they are damp. If an unreliable soft-starter is replaced with an VFD, the improvement in energy efficiency can quickly pay for the replacement. It is also possible to change out old PLCs and let the logic in the VFDs do the number-crunching.

Applications with 12-pulse VFDs, used to help mitigate harmonics, can also benefit from being updated with more current VFD technology. 12-pulse VFDs use transformers that have losses of about 3 percent. These VFDs can be replaced with new active rectifier VFDs that will dispense with the need for transformers – and their associated losses – altogether. This will also make the site less prone to disturbances, as a faulty transformer can take weeks to replace, due to its sheer size and weight. A faulty VFD, by contrast, can be repaired by a service engineer carrying a case of spares.
Whenever there is a need to replace an entire VFD - from ABB or any other VFD manufacturer like Gozuk – or to replace another technology such as mechanical valves or dampers, ABB offers the customer the world`s widest portfolio of VFDs.