Research on Magnetic Crosstalk Characteristics of Straight Light Path Type Optical Current Transformer

The straight light path type optical current transformer is exposed to the magnetic field interference in the three-phase power system. In this paper the mathematical model of magnetic interference rate (MIR) of straight light path type optical current transformer was established, and the MIR characters of straight light path type optical current transformer were researched. The research showed that the structural parameters of straight light path type optical current transformer are the key factors influencing the MFI of straight light path type optical current transformer, and the study discovered that the MIR of straight light path type optical current transformer decreases with the decreasing length of the magneto-optic crystal or distance between the magneto-optical and the current to be measured. Basing on that, an optimization method was proposed to improve the anti-interference ability of straight light path type optical current transformer by reducing the distance between the magneto-optic crystal and the current to be measured. The experimental results showed that the error of straight light path type optical current transformer induced by magnetic crosstalk decreased by at least one order of magnitude when the distance between the magneto-optical and the current to be measured reduced from 20cm to 4.4cm. The experimental results are consistent with the theoretical analysis conclusions, and that demonstrates the correctness and practicality of the proposed optimization method.