In the production process of semi-finished products and finished products of power transformers, before the newly installed transformers are put into operation and according to the precautionary test regulations of the State Ministry of Electricity, it is required to test the turn ratio or voltage ratio of the transformers in operation regularly. The traditional variable-ratio bridge is complicated to operate, the reading is not intuitive, and the necessary conversion should be carried out. The test can only be carried out in a single phase, and the work efficiency is low. HYG-3000 transformer ratio group tester overcomes the shortcomings of traditional ratio bridge test. The screen adopts large screen dot matrix LCD display, which has Chinese menu prompting function, simple and intuitive operation, completes three-phase ratio test at one time, and has fast test speed, high accuracy and perfect protection function.