Detection of arc- or corona-discharge in SF6-insulated equipments by using an OTDR method and corner cube prisms coated with dye films

An optical sensing system to detect are or corona discharge for a stack of SF6-gas-insulated equipments has been proposed by using corner cube prisms sensor heads and an OTDR (optical time domain reflectometry) method. The corner cube prisms have their three total reflection planes coated with a thin film of methyl orange dye by vacuum evaporation. The color of methyl orange dye changes through its chemical reaction with the decomposition products of SF6 such as HF gas. The optical sensing system can be applied to monitor individual gas-insulated equipments collecting to identify the equipment in trouble once the discharge happens. (C) 1998 Elsevier Science S.A. All rights reserved.