This instrument is a transformer tester developed on the basis of detailed analysis of the mathematical model of the transformer. When performing transformer verification, there is no need for high-current power supply, large standard transformer and load box. Just bring this instrument to measure the ratio and angle differences of current transformers according to national standards. It can also measure current 1%~ The ratio difference and angle difference of any percentage between 120%; can directly measure the transformation ratio of current transformer and voltage transformer; can qualitatively measure the ratio difference and angle difference of voltage transformer; can measure the actual current and voltage transformer on site The verification is particularly convenient for the secondary load.