New UL classification for silicone transformer fluid

This paper describes the protocol, apparatus, and results of high power arcing tests performed on a silicone transformer fluid. Testing performed in 1992 led to a “Less Flammable per NEC 450-23” Classification from Underwriters Laboratories which was comparable to that of a hydrocarbon based fluid. Evaluations performed during 1993 uncovered and confirmed unique advantages of the material which allowed a relaxation of the “use restrictions” associated with the listing. The implications for both OEMs and transformer specifiers are reviewed