Publication: The Journal of Electricity, Power and Gas
San Francisco, CA, United States
TRANSFORMER PRIMARY CUT-OUT.
AN improved form of a transformer primary cut-out designed to protect the high tension side of transformers is being introduced by the Westinghouse Electric and Manufacturing Company. It is made entirely of porcelain, and its form is such that it has liigh insulating and arc breaking qualities.
The plug to which the fuse is attached projects between the terminals, the upper end of it rising well into the top of the block and interposing an effective barrier, and thus making it impossible to maintain an arc. The fuse is eleven inches in length, making a long break, and is so placed that the vapors of a discharge are blown down and out of the device and away from the terminals.
The line wire is carried directly to the top of the device and attached to it as to an ordinary insulator, which it thus displaces. To reach the terminal the wire must be bent around the edge of the block and is so supported to an angle between the terminal post and the porcelain case that it cannot be loosened by any swaying of the wind. The plug enters from the bottom. When it is raised into place a partial turn draws the knife blades on the plug into the jaws on the block, preventing the plug from dropping out or being blown out. All live parts are protected from the weather by the projecting edges of the block and by placing the terminals well above its lower surface, with no apertures in the side or top. A bend in the fuse wire brings it into plain view at all times, and it is thus possible to observe its condition without removing the plug, guarding against any liability of opening the circuit when there is a current upon the line. It is fastened to the cross-arm or other support by two screws passing through porcelain tubes which form a portion of the block. It has a rated capacity of 2500 volts, 30 amperes. It is small, light, easy to install and to re-fuse, and forms a very desireable addition to the assortment of high grade electrical line apparatus.