ABSTRACT
High-voltage transformers are monitored in order to avoid unnecessary electric power interruptions and to extend the transformer's service life (Lorin, 2005). One approach has been to monitor the electrically insulating oil in which the transformer is immersed using several techniques (Bureau of Reclamation et al., 2005), including optical ones such as colour index (CI) (Nadkarni, 2007). The use of chromatic techniques for monitoring changes in the optical spectra of polychromatic light transmitted through the oil has been shown to provide a versatile means to yield additional information to that obtained with CI and other techniques. A number of convenient-to-use, cost-effective systems for such chromatic monitoring have been investigated (Elzagzoug et al., 2014) which use different combinations of polychromatic light sources (white LED, visual display unit [VDU] screen) and optical detection units (spectrometer, mobile phone cameras). The use of a combination of a VDU screen and a mobile phone camera has been shown to be attractive in providing a tunable polychromatic light source with a user-versatile detection unit.
