Analysis of Influencing Factors of Miniature Current Transformer Error

From a structural point of view, the so-called Miniature Current Transformer mainly includes three major components, namely the iron core, the primary coil and the secondary coil. Due to the existence of iron core magnetoresistance, Miniature Current Transformer must consume a small amount of current for excitation in the process of transferring current to magnetize the iron core, thereby generating induced potential and secondary current in the secondary coil, that is, there will be a certain amount of current. error.

In fact, the error of Miniature Current Transformer mainly comes from the excitation current consumed by the iron core, and its error mainly includes ratio difference and phase angle difference. The influencing factors of its error mainly include four aspects, namely: 1. Internal parameters of the current transformer; 2. The size of the core section; 3. The number of turns of the coil; 4. Reduce the core loss and improve the permeability.

For Miniature Current Transformer, its internal parameters have obvious influence on its error. These include the internal resistance and leakage reactance of the secondary coil. Similarly, the influence of the iron core section on the error is mainly manifested as: when the iron core section increases, the magnetic flux density of the iron core decreases, and the excitation current decreases, thereby improving the ratio difference and angle difference. 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 does not decrease much, and the more the magnetic flux density is. Smaller effects are worse.

In addition, the number of coil turns in the Miniature Current Transformer will also have a certain impact on the error. In general, increasing the number of coil turns is to increase the ampere-turn. 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 section.

In addition, if the loss of the iron core 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 difference and angle difference. Therefore, the use of high-quality magnetic materials and appropriate annealing processes can improve the permeability and The purpose of reducing loss.