A transformer turns ratio tester is a professional device specifically used to measure the voltage ratio of power transformer windings. It can accurately determine the voltage ratio between transformer windings, which is crucial for ensuring proper transformer operation and maintenance. This article details the working principle, classification, application fields, and usage precautions of transformer turns ratio testers. Working Principle: The basic working principle of a transformer turns ratio tester is to apply a known voltage to one side of the transformer (usually the high-voltage side) and then measure the output voltage on the other side (low-voltage side) to calculate the turns ratio. Main steps include signal generation, signal output, signal acquisition, data processing, and result display. Classification: Manual turns ratio tester, automatic turns ratio tester, portable turns ratio tester, and multifunctional turns ratio tester. Application Fields: Power industry, manufacturing, research institutions, education and training, and laboratories. Advantages: High precision, multifunctionality, automation, portability, ease of operation, and data management. Usage Precautions: Safety protection, equipment inspection, correct connection, environmental adaptation, professional training, and regular calibration. Conclusion: The transformer turns ratio tester is an important tool for ensuring transformer performance and reliability. By using advanced testing technology and multiple functions, it can accurately measure the transformer turns ratio, ensuring safety and stability in actual operation.