The Inertaire Transformer

Oxidation is the cause of almost all of the troubles that develop in service in connection with transformer oil and it is thought by the authors of this paper that the obvious remedy for such troubles is to isolate the oil completely from contact with the oxygen of the air. A new method of providing this complete protection in the Inertaire transformer is described. In this transformer, a body of insert gas??nitrogen??is automatically created and maintained inside the case above the surface of the oil. This nitrogen is obtained from the outside atmosphere by a breathing process in which the breathed air passes into the transformer through chemicals which absorb the 21 parts of oxygen, leaving only the 79 parts of nitrogen to pass into the case. A second purpose of the nitrogen gas is to eliminate the danger of fire or explosion above the oil surface for no fire or explosion can start or continue without oxygen. A distinction is made in the paper between a ``primary explosion,´´ which term is used to designate a sudden abnormal pressure produced by gas expansion due to arcing in the oil, and a ``secondary explosion´´ by which is meant an abnormal pressure produced by the combustion of an explosive mixture of gases. The hazard of the secondary explosion is eliminated by the absence of oxygen and effective protection against the primary explosion is given by the cushioning effect of the nitrogen body and a new form of diaphragm relief device.