In the process of semi-finished and finished production of power transformers, before the newly installed transformers are put into operation and according to the state Grid's preventive test rules, it is required to test the transformer's turn ratio or voltage ratio regularly.The traditional variable ratio bridge operation is tedious, the reading is not intuitive, and the necessary conversion, the test result is only one phase change ratio value.The transformer transformer ratio tester overcomes the shortcomings of the traditional transformer ratio bridge test, the screen uses a large screen high resolution LCD screen, convenient to use in the field, with Chinese menu prompt function, simple and intuitive operation, a complete three phase change ratio test, test speed, high accuracy.