Utilized the domestic and foreign technique and innovatively designed, the filter has a good ratio of price-performance. With the advantages of high working vacuum, high filtration speed, oil quality protection, the filter advanced the oil treatment technique and equipment performance and once can raise the puncture voltage up to over 35V. The series products can be installed by sealed regular or movable with a trailer, so it is suitable to treat oil, fill oil in vacuum chamber and circulating dry hot-oil when large transformer is being installed and overhauled.