PORTABLE OPTICAL PROBE FOR MONITORING OFTRANSFORMER OILS

Abstract

Transformer oils, which are used for cooling and insulation, need to be monitored in order to ensure that their performance is reliable and safe, so that maintenance can be carried out when necessary. Therefore techniques that help to define the ageing status of transformer oil are essential.In the present work fundamental research has been carried out to study the fluorescence emission spectra of three types of transformer oils (Shell Diala S2-ZUI, Nytro Libra and 10 GBN). Two optical systems were used. The first system (A) uses a 404 nm Gallium Nitride (GaN) semi-conductor laser diode as the excitation source while the second system (B) uses a 365 nm LED.Baseline data on the fluorescence emission of the three types of oils were obtained first. Based on detailed analysis of the spectral profiles changes in oil samples aged over a range of time intervals, a new method based on the sum of two normalised peak intensities was proposed and tested. Taking into account of the experimental errors, this method has been shown to be able to resolve the changes in the oil conditions.The performance of the Principal Component Analysis method was also assessed by applying it to the different types of oils. Results show that although it is capable of differentiating the overall changes in oil conditions, it is less effective for oils that emit fluorescence spectra profiles differing only in the overall intensity. Thus care has to be taken in the application of this method for oil monitoring. The method based on the sum of normalised peak intensities is preferred because it is effective, fast and convenient to apply.The applicability of the portable system (System B) as an alternative to the laboratory based condition monitoring system (System A) has been discussed, based on the results.

Date of Award	3 Jan 2015
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Krikor Ozanyan (Supervisor) & Zhongdong Wang (Supervisor)