Gas Bubbles In Distribution Transformers

Gas bubbles are known to have a deleterious effect on the dielectric strength of transformer oil. The possibility that such bubbles may develop in oil-filled distribution transformers and may cause excessive failure rates is thus of concern to both manufacturer and user. The paper presents new information relative to failure mechanisms in transformers. It describes some of the operating conditions which may lead to gas bubble formation and it gives limited data showing the effect of bubbles on insulation breakdown strength.