VFD With By Pass DOL Starter

The above panel illustrates a typical VFD panel with by pass arrangement. VFD starters are bought out for which by pass arrangement with auto isolation of the VFD is done.

VFD’s are bought out and connected to series reactors either a both incoming and outgoing or on the out going side (as needed by customer) are connected through incomer and outgoing contactor to the system and motor respectively. The major problem is this case is arrangement of a by – pass system.

In the by – pass system, say a DOL by pass, in addition to two input and output contactors one more by pass contactor is used . The inter lock will be such that, the by pass contactor can be switched only when both the incomer and outgoing contactors of the VFD are switched off.