What are the common challenges when using a split-core current transformer in industrial environments?

Accuracy and calibration

Flux leakage

In open-close current transformer, the opening and closing of the iron core will lead to leakage of magnetic flux. Because the core is not a complete, continuous loop like a solid core transformer, part of the magnetic field line may escape through the gap. This can lead to inaccurate ratios. For example, if the transformer is designed with a ratio of 100:1 (the ratio of primary current to secondary current), magnetic flux leakage may bias the actual ratio, resulting in an error in current measurement.

Calibrating an open-close current transformer to achieve high accuracy can be more difficult than a solid core transformer. Due to the presence of opening and closing sites and possible leakage of magnetic flux, the core and winding parameters need to be adjusted more precisely during calibration.

Accuracy issues related to load

The accuracy of the open-close current transformer is greatly affected by the secondary load. In an industrial environment, the load on the secondary side can vary greatly depending on the measurement or protection equipment connected. If the load impedance is not within the specified range, it will lead to an error in the measured current. For example, if the load impedance is too high, the secondary current may not be precisely proportional to the primary current.

Installation and mechanical stability

Correct closure of the opening and closing core

It is essential to ensure that the opening and closing core is properly closed around the conductor carrying a primary current. In an industrial environment, there may be vibration, mechanical shock, or temperature changes that can cause the opening and closing core to slightly open or misalign. This breaks the magnetic coupling between the primary and secondary windings, resulting in inaccurate current measurement. For example, in a plant with heavy machinery in operation, vibration can gradually loosen the closure of an on-off current transformer.

Mechanical strength and durability

Industrial environments are often harsh, with factors such as dust, moisture and corrosive substances. Open-close current transformers need to be mechanically strong enough to withstand these conditions without being damaged. Materials used in transformer construction, such as core materials and housings, must be resistant to corrosion and mechanical damage. If the core or winding is affected by corrosion or mechanical wear, the electrical performance of the transformer will change and the accuracy will be reduced.

Electromagnetic interference (EMI)

External electromagnetic interference sources

Industrial facilities are full of sources of electromagnetic interference, such as large motors, generators, and power electronics. These sources of electromagnetic interference induce unwanted voltage and current in the on-off current transformer. The induced interference will superimpose on the normal output of the transformer or distort it, making it difficult to measure the primary current accurately. For example, when a nearby high-power motor is started, it generates a strong electromagnetic field, which may be coupled to the current transformer.

Electromagnetic interference shielding

Providing effective electromagnetic interference shielding for open-close current transformers in industrial environments can be challenging. Compared with solid core transformers, the open-close design may make it more difficult to achieve complete shielding. Without proper shielding, the transformer may be more vulnerable to external electromagnetic interference, which can affect its performance and accuracy.