Under the influence of DC bias

the iron core of the current transformer is prone to saturation

causing the ratio error to shift towards negative direction and the phase error to shift towards positive direction

resulting in measurement inaccuracy. This paper discusses the principle of the impact of DC bias on the error of current transformers

introduces a new type of anti-DC bias current transformer

which has anti-DC bias function compared to traditional current transformers. The paper briefly describes the verification requirements

methods

and schemes of anti-DC bias current transformers

and conducts a large amount of experimental verification work. The paper also develops an AC / DC standard current transformer based on self-excited oscillation flux gate technology and magnetic integrator technology with an accuracy level of 0.02

which can measure both DC and AC

and has been applied in the error verification of anti-DC bias current transformers

achieving good results.