Patent ID: 7078643
Filing Date: 2006-07-18
Classification: H01H

Abstract:
1. An electric power switch, comprising: an impedance; a power contactor comprising a fixed contact and a moving contact operable for closing an electric power circuit on a closing stroke and opening the electric circuit on an opening stroke; an impedance contactor operable for entering the impedance into the circuit on the closing stroke and removing the impedance from the circuit on the opening stroke; the impedance contactor comprising an annular retracting contact surrounding the fixed contact of the power contactor and an annular traveling contact surrounding and moving with the moving contact of the power contractor; and a timing device comprising a pneumatic chamber within the retracting contact vented by a restrictive orifice operable for causing the impedance contactor to close before the power contactor on the closing stroke, and to cause the impedance contactor to open before the power contactor on the opening stroke.