Northern Telecom Limited

Paul A Taylor

William P Trumble

James E Anderson

Francis Y Hung

George J Borkowicz

An overvoltage protector for protection of telecommunication equipment having a pair of line terminals, and a respective pair of levers forming part of the ground circuit, with an overvoltage protective device bonded under tension between each line terminal and each respective lever. When an overvoltage destroys one or other device, or the bond between the line terminal and the respective lever disappears, that lever pivots about a single fulcrum under a force applied by a spring and the end of that lever contacts the line terminal. This ensures an electrically conductive relation between the line terminal and the ground circuit. As a result, the equipment to which the overvoltage protector is applied is protected from lightning and successive overvoltage occurrence.

Overvoltage protector

An overvoltage protector for protecting equipment, especially telephone equipment, against high voltage surges such as are caused by lightning in the vicinity of the equipment or the cables to which it is connected, comprises one or more overvoltage protectors (42,58) mounted upon one face of an insulating support (18). A generally planar contact member (62) mounted upon the support member has a ground contact member (90) to make contact with a ground electrode (114) in the equipment to be protected and with each overvoltage protector. A spacer (60) of fusible plastics material extending between the contact member (62) and an interconnection (26) to one terminal (42A) of the protector melts when a sustained fault occurs. As the spacer melts, it permits an electrical connection between the contact member and the line to which the overvoltage protector is connected, effectively short-circuiting the line to ground. Overcurrent protection may be provided by means of a resistor (116) disposed in series with the line and located close to the plastics spacer so as to heat the spacer when an overcurrent occurs. In one case, the spacer comprises a film interposed directly between a pair of contacts which serve to short-circuit the protector. In another case, the spacer comprises a limb with relatively thin lateral projections which melt and shear. In both cases, the spacer preferably comprises high density, high molecular weight polyethylene.

Growing community of inventors

CA

Paul A Taylor