Working model of optical fiber sensor for estimation of sludge in oil in electrical transformer

摘要

A working model of an optical fiber sensor for estimation of sludge in transformer oil is presented based on evanescent field of absorption. The method proposed consists of a multimode glass fiber of diameter 62.5/125 pm operated at 1100 nm wavelength. The external jacket and cladding of the fiber are removed at different points along the length of the fiber and along with the coils immersed in transformer oil. The two ends of the fiber are taken out from the transformer; one end of it is connected to a ANDO (1100 nm) power source while the other end is connected to an optical power meter coupled with a relay and circuit breaker. The method presented will be of great use for estimating the formation of sludge in transformer surrounding the coils and thereby prevent its damage due to formation of sludge. With little effort, the working of the system can be made on-line and monitored from a central office.