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, the transformers are required to carry out turn-to-turn or voltage-to-voltage ratio tests. 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 Variable Ratio Tester Series overcomes the shortcomings of traditional Variable Ratio Bridge Testing. The screen uses large screen color LCD display, Chinese menu prompt, simple and intuitive operation, complete three-phase ratio test at one time, fast test speed, high accuracy, perfect protection function.