But Oil oxidizes and creates oxidation by-products which in turn destroy the paper. To maximize the life of the paper insulation, oxidation of the oil must be controlled.
Damage to paper insulation cannot be repaired
Degradation of transformer insulation is combination of three main factors:
"MOISTURE KILLS TRANSFORMERS"
Introduction: Those responsible for transformer maintenance generally recognize that water in transformers is a problem. However, the relationship of water to oil and cellulose is less understood, as is the impact of water on cellulose, over an extended period of time.
Oil Leaks: It is very important to recognize the significance of an oil leak. Oil loss is consequential but on the cooling down cycle moisture drawn in.
A ready source of moisture.
When a transformer is left "sitting around" or is very lightly loaded it will become wet