This paper presents a design for a low loss long life high current contactor consisting of a mechanical contactor teamed with an electronic circuit that eliminates switching stress on the mechanical contacts. A design for a practical 115V 3 phase double throw current protected Hybrid Contactor is presented, along with laboratory and field test data.
The idea for a hybrid contactor is not a new one, having been applied since electronic devices became readily available in the 1960s. The key concept is to parallel the mechanical contacts with electronic devices (thyristors or FETs) to handle the current during mechanical contact transition. The mechanical contactor is specially designed to provide low conduction losses without needing to withstand arcing events. The contactor also includes bus control and over-current protection features.