Analysis of Influencing Factors of Miniature Current Transformer Error

The influencing factors of the error mainly include four aspects: 1. The internal parameters of the current transformer; 2. The size of the iron core section; 3. The number of turns of the coil; 4. The reduction of iron core loss and improvement of magnetic permeability.

For the miniature current transformer, its internal parameters have obvious influence on its error. Including the internal resistance and leakage reactance of the secondary coil. Similarly, the core cross-section has a large impact on the error: when the core cross-section increases, the magnetic flux density of the core decreases, and the excitation current decreases, thereby improving the ratio and angle differences. Under rated conditions, if there is no compensation function, the magnetic flux density of the iron core is already very small, so reducing the magnetic flux density also reduces the permeability coefficient relatively, so that the excitation current is not reduced much, and the magnetic flux density is increased. The smaller the effect, the worse.

In addition, the number of coil turns in the miniature current transformer will also have a certain impact on the error. Under normal circumstances, increasing the number of coil turns is to increase ampere-turns. Increasing the number of turns can reduce the magnetic flux density. The effect of improving the error is much more significant than increasing the core section.

In addition, if the core loss in the miniature current transformer can be effectively reduced, and the magnetic permeability can be further improved, the error can also be reduced. Under the condition that the magnetic flux density of the iron core remains unchanged, reducing the excitation ampere-turn and loss ampere-turn of the iron core will also improve the ratio and angle difference. Therefore, the use of high-quality magnetic materials and appropriate annealing processes can achieve improved permeability and The purpose of reducing losses.