Heat sensitive fault detecting and indicating system for watthour meter

Abstract

A heat sensitive fault detecting and indicating system and method for a watthour meter is disclosed herein. The illustrated watthour meter includes a potential stator and a current stator both of which are mounted on a frame assembly, the assembly also having mounted thereon one or more permanent magnets and a rotatable disk assembly with disk rotation being recorded on the recording dials of a register assembly visible through the enclosing glass cover of the meter. The current stator includes a pair of current coils which coils have a heat sensitive fault detecting and indicating device associated therewith. The heat sensitive fault detecting and indicating device illustrated includes a layer of low melting point metal, such as tin, for example, which layer is covered by a sheath, such as a plastic sheath, for example, with predetermined portions of the sheath being thinned, as by embossing, for example, with a predetermined symbol or other indicia. When a current surge is experienced at the watthour meter producing sufficient heat at the current coils, the low melting point metal melts and penetrates the thinned area of the sheath thereafter indicating that a possibly damaging surge has been experienced by the meter. The indication that a surge has occurred is preferably made readily visible through the glass cover to facilitate meter monitoring.