The wiring method of Electrical Current Transformer is determined according to the operating requirements of the load it is connected to. Rated transformation ratio and error: The rated transformation ratio KN of the Electrical Current Transformer refers to the rated current ratio of the Electrical Current Transformer. When the primary current of the Electrical Current Transformer changes within a certain range, it is generally specified as 10～120%I1N, the secondary current should be changed proportionally, and the primary and secondary voltage (or current) should be in the same phase. However, due to the internal impedance, excitation current and loss of the transformer, the ratio and phase errors are called ratio and angle differences. For the Electrical Current Transformer that has not taken compensation measures, the ratio difference is negative and the angle difference is positive. Both the absolute value and the angle difference of the ratio difference decrease as the current increases.