Patent ID: 6189479
Filing Date: 2001-02-20
Classification: G01K

Abstract:
A heat-sensitive warning device for detecting an increase in the temperature of an electrical insulator, said device comprising:(a) an operating mechanism comprising:(1) a housing made from a material which can transfer heat, said housing being in thermal contact with said electrical insulator or with a device for attaching said operating mechanism to said electrical insulator, and said housing having an open first end and a partially open second end having an opening;(2) a spool, said spool being inside of said housing, and said spool being of a size which allows it to pass through said open first end;(3) an indicator element, said indicator element being wound around said spool, and said indicator element having a first end secured to said spool and having a second end secured to said housing;(4) a first thermosenstitive end plug which seals said open first end of said housing, said first thermosensitive end plug being made from a material which melts at a first preselected temperature above ambient temperature and at or below a second preselected temperature;(5) a second thermosensitive end plug which seals said opening in said partially open second end of said housing, said second thermosensitive end plug being made from a material which melts at said second preselected temperature, said second preselected temperature being above ambient temperature, being at or above said first preselected temperature and being below an unsafe temperature for said electrical insulator; and(6) an ejection mechanism positioned within said housing for ejecting said spool and said indicator element through said open first end of said housing to an area outside of said housing upon the melting of said second thermosensitive end plug, said ejection providing a visual indication of an increase of the temperature of said electrical insulator; and(b) a device for attaching said operating mechanism to an outer surface of said electrical insulator, said device being in thermal contact with said electrical insulator.