- dielectric strength at 90ºC/194ºF;
- water extract reaction;
- acid neutralization number;
- particulate matter content in mircons; and
- free water and moisture content.
Purchasing transformer oil is an important financial decision for your company. It should be done very responsibly. First, the buyer must a choose a brand of oil. This requires careful consideration based on the type of equipment being used and the operating conditions the oil and the oil’s abilty to meet those conditions. Second, the cost of the oil must be considered. A small price difference in the cost of just one liter small can turn into a significant amount of money when purchasing a large volume of oil. There are no universal recommendations for buying transformer oil. There are however, online services allowing buyers to compare transformer oil prices from various suppliers. It is up to the buyer to research and choose a reliable wholesale distributor or retailer. If you have already purchased transformer oil that meets the correct specifications and quality standards, then it is time to think about oil storage. The practical way to store the oil is to use clean and dry, steel air tight vessels. The tanks are usually coated with an oil resistant material inside. The outside of the tanks should have anticorrosion and light reflecting coating. The acceptable range of temperatures for storage of transformer oil is -40ºС to +60ºС/-40ºF to +140ºF. The vessels should be equipped with valves for filling and draining as well as a manhole for cleaning, inspection and repairs. Breathing systems must be equipped with silica gel or zeolite cartridges that can be monitored by special monitoring devices. Three days after putting the oil into a storage tank, samples are normally taken for laboratory analysis. Transformer oil in storage should be tested at least once a year for the following parameters: