Analysis of influencing factors of micro current transformer error

- May 30, 2018-

From the structural point of view, the so-called micro-current transformer mainly includes three major components, namely, iron core, one coil and two times coil.

Due to the existence of core magnetic resistance, micro-current transformer in the process of transmission of variable current, must consume a small amount of current for excitation, so that the core magnetization, so that two coils to produce inductive potential and two times, that is, there will be a certain error. In fact, the error of micro-current transformer mainly originates from the excitation current consumed by the core, and its error mainly includes the ratio difference and the phase angle difference.

The influencing factors of its error mainly include four aspects, namely: 1, the internal parameters of the current transformer, 2, the size of the Iron core section, 3, the number of coil turns, 4, the reduction of iron core loss and the improvement of magnetic conductivity. For the micro-current transformer, the internal parameters have obvious influence on its error. These include two coil resistance and leakage resistance. Similarly, the main effect of iron core truncation on error is that when the section of iron core increases, the flux density of iron core decreases and the excitation current decreases, thus improving the ratio difference and angular difference.   

Under the rated conditions, if there is no compensation function, then the flux density of the iron core has been very small, so reducing the flux density also relatively reduced the magnetic conductivity coefficient, so that the excitation current is not much reduced, and the smaller the flux density, the worse the effect. In addition, the number of midline circle turns of micro current transformer will also have a certain impact on the error.

Usually, increasing the number of coil turns is to increase the turn, increasing the number of turns can reduce the flux density, and the effect of improving the error is much more significant than the increase of the iron core cross section. In addition, if it can effectively reduce the loss of the core in the micro-current transformer, and further improve the magnetic conductivity, then the error can also be reduced. Under the condition that the magnetic flux density of iron core is constant, reducing the excitation and loss of iron core will also improve the ratio difference and angular difference, so the use of high quality magnetic materials and the adoption of appropriate annealing process can achieve the goal of improving magnetic conductivity and reducing wear and tear.