YDJ series oil immersed testing transformer is based on the Electromechanical department’s “testing transformer” standard and through foundation of productions, we make great progress, and YDJ series testing transformer and national standard-T-9641-1999 and through our promotion. This series of product has the benefits of light, portable, well structure, multi-functional and convenient properties. Especially applies to the electric power system, mining company, scientific research institute and so on and it can take the testing to the high voltage electric equipment, electric elements, insulation tests of insulating materials under power frequency or high voltage current conditions. It is indispensible equipment in high voltage testing.