The transformer capacity characteristic tester comes with a high-efficiency rechargeable battery, allowing it to operate without an external power supply. One charge can continuously measure dozens to hundreds of units. At the same time, the internal digital synthesis of three-phase standard sine wave signals (not a simple inverter AC output, ensuring the accuracy of test data under non-rated conditions) provides a three-phase precision AC test source through a power amplifier. When measuring transformer capacity and short-circuit losses, there is no need for external three-phase test power supplies, voltage regulators, current boosters, and other auxiliary equipment, simplifying wiring and greatly improving work efficiency. The capacity test result accuracy reaches 100%. It is equivalent to two devices: an active transformer capacity tester and a transformer loss parameter tester. It can precisely measure a series of power frequency parameters such as capacity, no-load current, no-load loss, short-circuit loss, and impedance voltage for various transformers. The transformer capacity characteristic tester has the advantages of small size, light weight, high measurement accuracy, good stability, and simple and easy operation. It can completely replace the previous method of measuring transformer losses and capacity using multiple meters, with simple wiring, convenient testing and recording, and greatly improved work efficiency. The transformer capacity characteristic tester uses a large-screen graphic liquid crystal display as the display window, with graphic menu operation and Chinese prompts, integrating multiple parameters on one screen. The human-machine interface is friendly, easy and quick to use, making it the preferred product for power users at all levels.