Optical sensor for transformer monitoring

Transformers are a vital part of transmission and distribution systems. Monitoring the transformers for problems before they occur can prevent faults that are costly to fix and result in a loss of service. Current systems can provide information about the state of a transformer, but are very expensive to implement. This paper outlines a new approach that is based on using light absorbance to monitor the transformer oil. Oil is continually sampled from the transformer, and light is passed through the oil and tested for absorbance. Preliminary experiments have demonstrated that a system based on certain wavelengths could determine the difference between an acceptable or unacceptable sample of oil. Samples of a failed transformer showed a general increase in absorbance during the experiment. Additional wavelengths can be identified, which provides more information about the state of the transformer and makes the system more versatile in determining fault types. Basic principles of operation experimental data and a prototype of this monitoring system are presented.