The LEX Oil Conditioning System (LEX-OCS) is a stationary, maintenance-free system that removes both free and dissolved moisture while reconditioning the oil on line. This economical and easy-to-use system extends the life of insulating oil and also the life of cellulose insulating materials over a period of time, by reducing moisture in paper via oil, paper, and temperature moisture dynamics. It does this while the transformer remains in service, utilizing a molecular sieve filter media without the need for heating or vacuum.

Effect of moisture materials on transformer performance
The insulation system of most power transformers consists of organic materials: mineral oil, cellulose paper and pressboard. Moisture in the insulation system, together with operating temperature, constitutes the most important transformer insulation aging mechanism. Maintaining transformer insulation in a properly dried out state can be a difficult and expensive process; it requires considerable labor, capital-intensive equipment and at times, transformer outages.

Removing moisture from a wet transformer usually involves draining and drying the oil, drying the solid insulation using heat and/or vacuum, and vacuum refilling the unit. A more practical and less expensive method is to use the oil as a transfer media to remove moisture from the solid insulation. As the oil is dried (most favorably when the transformer is hot), the moisture will be transferred from the solid insulation to the oil, based on the relative solubility at a given temperature. This process does not introduce air into the system, so degassing the oil will not be required. And the transformer may be dried while energized.

The time required to remove moisture from a transformer depends largely on the operating temperature. When lightly loaded (low operating temperature), the migration of water from the paper to oil is slow. At higher operating temperatures, the equilibrium between water in paper and oil shifts to increase water content in oil and the LEX-OCS can remove dissolved water much more effectively. With freshly activated LEX media in each cartridge, the LEX-OCS has the capacity to remove approximately 12.8 kg. of moisture.

For complete information on the LEX OCS, view our brochure. (Requires Adobe Reader)