ELECTRICAL SWITCHING APPARATUS WITH IMPROVED CONTACT ARM CARRIER ARRANGEMENT

摘要

The contact fingers of electrical switching apparatus have radial convex surfaces centered on the pivot pins which seat on concave surfaces in the molded contact carrier to transmit bending loads on the pin into the carrier. A seal member which snaps onto the end of the pivot pin has fins which extend between the contact fingers to block flow of arcing gases through the carrier. For lower current ratings, some of the contact fingers are replaced by annular spacers which also transmit bending moments into the carrier and restrict gas flow. A stop ledge on the carrier against which the contact springs bias the contact fingers has a recess which allows the center fingers to project farther toward the stationary contacts so that the arc toes on these fingers are the last to separate on opening and the arc is concentrated on them. The drive pin connecting the carrier to the operating mechanism has flats which key it for engagement in a slot in the carrier for installation and removal only with the carrier pivots lifted out of their bearing pockets by removal of the rear casing.