The transformer capacity characteristic tester comes with a high-efficiency rechargeable battery, allowing operation without an external power supply. One charge enables continuous measurement of dozens to hundreds of units. Meanwhile, 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, or other auxiliary equipment, simplifying wiring and greatly improving work efficiency. The capacity test result accuracy reaches 100%. This device 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 for various transformers, including capacity, no-load current, no-load loss, short-circuit loss, and impedance voltage. The transformer capacity characteristic tester has the advantages of small size, light weight, high measurement accuracy, good stability, and simple and easy operation, fully replacing the previous multi-meter method for measuring transformer losses and capacity. With simple wiring and convenient testing and recording, it greatly improves work efficiency. The transformer capacity characteristic tester uses a large-screen graphical LCD as the display window, with graphical menu operation and Chinese prompts, integrating multiple parameters on one screen. The user-friendly interface is simple and quick to use, making it the preferred product for power users at all levels.