Electrical contact for use in a current interrupting unit

Abstract

A female interrupting contact for a current-interrupting unit includes a smoothly contoured, apertured pressure ring which is held in a groove formed in the wall of a bore through a contact body. A flat spring in the groove maintains the ring to one side of the bore so that the aperture is normally misaligned with the path of a male contact through the bore. When the male contact enters the aperture, it moves the ring against the action of the flat spring to align the aperture with its path. This alignment effects intimate sliding engagement between the male contact and both the ring and the wall of the bore, one or both of the latter of which are conductive so that a reliable, metal-to-metal, first electrical path through the contacts and the interrupting unit is established. The bore is elongated between the pressure ring and an end thereof from which the male contact exits, following which an arc is established between the contacts. This elongation is at least as long as the length of the male contact, so that after the intimate engagement ceases, a second electrical path is established via small arcs or arclets which form between the male contact and the wall of the bore. The length of time the second path exists may be selected so that when the unit interrupts the arc a switch or the like, with which the unit is used, is sufficiently far open to prevent an arc from forming therein.