(1) The influence of the internal resistance R2 and leakage impedance X2 of the secondary coil on the error: when R2 increases, the specific difference and angular difference increase; As X2 increases, the specific difference increases, but the angular difference decreases. Therefore, to improve the error, R2 and the appropriate X2 value should be minimized. Since the internal resistance R2 and leakage resistance X2 of the secondary coil are smaller than those of the secondary load Rfh and Xfh, the change of R2 and X2 has little effect on the error, only the effect on the small capacity current transformer is significant.
(2) The influence of the core cross-section on the error: the increase of the core cross-section reduces the magnetic flux density of the core and the excitation current, thereby improving the specific difference and angular difference. The magnetic flux density of the unbalanced current transformer is small under the rated conditions, so reducing the magnetic flux density will also reduce the permeability, so that the excitation current is not reduced much, and the magnetic flux density is smaller.
(3) The influence of the number of turns on the error: increasing the number of turns of the coil is increasing the ampoule. Increasing the number of turns can reduce the magnetic flux density, and the effect of improving the error is much more significant than increasing the core cross-section. However, an increase in the number of turns of the coil leads to an increase in the amount of copper, as well as a decrease in the dynamic stability coefficient and an increase in the saturation factor. In addition, for single-turn current transformers (e.g., grommeted or bushed current transformers, where only one turn is allowed), the error cannot be increased by increasing the number of turns.
(4) Reduce iron loss and increase permeability. Under the condition that the magnetic flux density of the core remains unchanged, reducing the excitation amperage and loss amperage of the core will also improve the specific difference and angular difference. Therefore, the permeability can be increased by using high-quality magnetic materials and employing a suitable annealing process. The purpose of reducing losses. The strength of the core also affects the saturation coefficient, and when the magnetic properties are poor, the saturation coefficient of the core is small.
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