Abstract: An electric power switch or contactor of the 3-pole AC type or the like is provided with means making it capable of withstanding higher fault currents such as short circuit currents. This is done by providing the insulating contact carrier with integrally molded stops that will allow the spring-biased bridging contacts to be blown slightly open by the high electro-dynamic forces occurring during high fault currents but will limit such opening of the contacts to gaps small enough to inhibit the arc from moving from between the contacts. Instead of attempting to keep the contacts closed under such conditions which would require a large magnetic force, allowing the contacts to open this small amount eliminates the need for a larger magnet, reduces the blow-open force and, more importantly, the small gaps will retain the arcs between the contacts and will inhibit them from flashing out to other parts of the contactor with consequent burning and destructive effect.

Abstract: A unitary three-phase current transformer having its three iron cores and three secondary coils enclosed and retained in their positions by a pair of like molded housing halves. The housing halves also have pairs of juxtaposed slots in their upper, adjacent edges for clamping pairs of secondary coil terminal inserts therebetween to mount the same so as to allow connection of the secondary coils to external conductors. The housing halves are connected together by symmetrically arranged sets of screws with the screws of each set extending through holes in the respective half and threaded into the respectively opposite half. The asembled housing halves provide three apertures through which are inserted respective bus bars serving as one-turn primary windings. A terminal strap is attached to one end of each bus bar, the bus bar is inserted through the aperture, and the other terminal strap is attached to the other end thereof.