Gas sensor to monitor the temperature of oil in an oil-cooled transformer by infrared gas absorption with laser diode and photo-detector

摘要

A sensor monitors the temperature of an oil-cooled transformer by determining the concentration of a selected gas using infrared gas absorption. The sensor consists of a laser diode (3), an absorption measurement path, a photo-detector (5) and an oil-free chamber linked to the transformer housing interior by a semi-permeable membrane (2). The gas measured is ethylene, ethyne, propane, propene, methane, oxygen, carbon dioxide or carbon monoxide. The detection lower threshold is 20 ppm. Measurement of ethylene concentration takes place using a discrete spectral line within the ethylene spectrum at about 3.3 The measurement and control system (7) is incorporated within a housing (1).