What are the sources of moisture in the insulation oil?

Insulating oil in the packaging transportation and storage management process, if improper storage it would absorb water, in addition petroleum products have a certain degree of water absorption,it can absorption and dissolved part water from the atmosphere or when contact with water,  insulation oil water absorbing capacity related with its composition and the temperature environment. Generally speaking in 20 ℃ degrees insulating oil dissolved water capacity for 40 x 10-6 or so, through the industrial dewatering device can make the moisture content of transformer oil to 10 x 10-6 or so, in addition oil absorption of moisture resistance with air relative humidity and oil temperature increase linearly. Such as sample in the 60℃, relative humidity is 40%,the water content in oil reached 80 x 10-6, when the relative humidity is 80%, oil moisture content reached 200 x 10-6.The water absorption can reach dozens of 10-6 due to different chemical composition of oil, the difference in the oil, the more aromatic hydrocarbon composition the higher oil hygroscopicity.