ABSTRACT
High-voltage transformers are an essential part of high-voltage electric power transmission systems. Their manifestation involves the use of wire windings immersed in electrically insulating oils, and they can be automatically switched to meet power demands using switches called tap changers. Continuous use over long time periods can lead to gradual deterioration, so monitoring them can assist in their maintenance and the avoidance of unnecessary power supply failures. Acoustic techniques have been used for such purposes (Cichon et al., 2011). However, monitoring such transformers is difficult because of the high voltages involved and the radio frequency active environment in which they operate making conventional electronic methods difficult to use (Warren et al., 1999; Gungor et al., 2010). The use of optical techniques based upon optical fibres provides a means for overcoming such difficulties provided suitable sensing approaches can be evolved (Jones and Spencer, 2013).
