The Transformer Turns Ratio Tester (also commonly known as the Automatic Ratio Group Tester) is a precision instrument specifically designed for transformer health checks. Its core task is to accurately measure the transformer voltage ratio (turns ratio), connection group, and polarity error.
Simply put, the working principle of a transformer is: primary coil turns / secondary coil turns = primary voltage / secondary voltage. The ratio tester verifies whether this ratio meets the design requirements on the nameplate by actually measuring the voltage on both the high and low voltage sides.
