What are the factors that affect the error of current transformer?

There may be errors in the use of current transformers, which is a normal phenomenon as long as it is within the controllable range. But what are the factors that affect the error of current transformers? Hemei Electronics Current Transformer Company will answer for you.

1. The internal parameters of the current transformer are the main factors affecting the error of the current transformer.

(1) The influence of the secondary coil internal resistance R2 and leakage reactance X2 on the error; (2) The influence of the core cross section on the error; (3) The influence of the number of turns on the error. (4) Reduce iron loss and increase magnetic permeability.

2. Current transformer operation error

When the current transformer is finalized and its internal parameters are determined, its error size will be affected by the secondary current (or primary current), secondary load, power factor and frequency. These factors are called external factors. The error of the current transformer in operation is mainly affected by these four factors.

(1) The influence of the change of current frequency on the error. (2) When the primary current decreases, the magnetic flux density decreases proportionally, but at low magnetic flux density, the decrease in excitation ampere is slower than the decrease in magnetic flux density. (3) The current transformer error has the following characteristics: when the primary current changes within the specified range, the secondary current changes proportionally, and when the secondary load impedance changes within the specified range, the secondary current size is not affected. Therefore, when the secondary load is reduced to the rated range, the magnetic flux density will also decrease. Since the secondary current is constant, the excitation current decreases and the error also decreases. The factory manual of the current transformer generally indicates the rated secondary load impedance value. During operation, the error should be checked according to the secondary load impedance value under the given wiring method.

(4) The power factor of the secondary load increases, that is, Rfh increases, Xfh decreases, the angle difference increases, and the ratio decreases.