There are several types of core structures for miniature current transformers

At present, the core materials commonly used for miniature current transformers include cold-rolled silicon steel sheets, permalloy and iron-based ultra-microcrystalline alloys. Silicon steel sheets can be used for both protection grade iron cores and general measurement grade iron cores. , It is widely used, and the price is relatively low. Permalloy and ultra-microcrystalline alloy materials have the characteristics of high initial permeability and low saturation magnetic rate, but the price is relatively high, and it is only suitable for measurements that require high measurement accuracy and strict instrument security factors. Grade iron core.

The commonly used iron core forms of miniature current transformers are laminated iron core, rolled iron core, open iron core, etc. The laminated core is made of cold-rolled silicon steel sheets that are punched and cut into strips along the rolling direction, and then the strips are stacked to form a mouth shape. The laminated core is mainly used in the use of miniature current transformers of 35kv and below.

The coiled iron core is made of strip cold-rolled silicon steel sheet. The shape is circular, elliptical and rectangular. The performance is very ideal; the open iron core is the coiled iron core after vacuum dipping paint or epoxy resin curing , And then cut into two or more petals on the cutting machine, pad the cut with a non-magnetic gasket with the required width of the air gap, and then tie it with a stainless steel belt to form a complete iron core.

When the shorting tab of the secondary side terminal of the miniature current transformer without load is not pressed, the terminal connection heats up, and the current transformer sometimes has electromagnetic noise. Once the load increases, the noise increases, and it is also closely related to the ambient temperature. When the ambient temperature is around 35 degrees Celsius, the sound starts to be abnormal.

The detachable current terminal connector of the miniature current transformer is not tightly connected. When the load is small, the terminal that is not tightly crimped will not heat up significantly, and it is not easy to find. When the operation mode is changed or the primary side load is too large, the through power on the primary side increases and the current increases, and the secondary side current also starts to increase accordingly. The terminals that are not tightly crimped will overheat.