Ageing of transformers is directly linked to the ageing rate of the cellulose insulation, which is affected by operating temperature, water and oxygen content and contaminants.
Oxygen ingression is of particular concern as it will greatly increase the oxidation of the oil and the ageing of the insulation.
It has been proven that the presence of high levels of oxygen in oil halves the life of paper insulation and that ideally oxygen levels should not exceed 3,000 PPM. A normal free-breathing transformer has an oxygen level of approximately 25,000 PPM.
A conservator Oil Preservation System (COPS) effectively controls the oxygen content and thus greatly slows down the ageing phenomena. This consists of a rubber cell or diaphragm mounted in the conservator that prevents the oil from coming into contact with air, and hence oxygen.
COPS can be retrofitted in the field to an existing conservator, or a new conservator with a COPS already installed can be supplied and fitted. A separate OLTC compartment with its own oil level indicator can be supplied if required.
When combined with a Transec moisture removal system, the COPS works very effectively to greatly extend insulation life, reduce the need for oil reclamation or replacement and decrease expensive maintenance.