Generally refers to the fully automatic transformer turns ratio and group comprehensive tester, also known as the transformer turns ratio tester or ratio tester. Its main purpose is to measure the turns ratio, group polarity, and error. It can automatically measure the turns ratio, group polarity, and error of various single-phase/three-phase transformers and voltage transformers. The turns ratio tester can check the correctness of the transformer's turns ratio, the condition of the tap changer, whether there is inter-turn short circuit in the transformer, and whether the transformer can operate in parallel.

The transformer turns ratio tester uses a single-chip microcomputer as the core for measurement calculation and automatic control. It features a fully Chinese menu operation interface, with advantages such as intuitive display, good stability, high accuracy, wide measurement range, and no need for a three-phase power supply on-site. It is a new generation of intelligent turns ratio testing instrument. It uses a large-screen Chinese character display and menu operation for ease of use. The turns ratio, group, and error can be measured in one go. After inputting the standard turns ratio, it can automatically calculate the relative error. Measurement results are automatically saved, and printing results allow viewing of previous data. For measuring on-load transformers, only one turns ratio input is required. The turns ratio tester is an ideal testing instrument for the power industry.

According to IEC and relevant regulations, the turns ratio of semi-finished and finished products during transformer production, as well as transformers after new installation and maintenance, must be tested before being put into operation. In the preventive testing regulations of the power department, periodic turns ratio testing of operating transformers is required. Through transformer turns ratio testing, the condition of the transformer winding turns ratio and tap changer can be checked, and it can be determined whether there are defects such as inter-turn short circuits in the transformer and whether it can operate in parallel, thereby ensuring the safe use of the equipment.