Introduction to basic knowledge about current transformers

News | company news | May 23,2024

Introduction to basic knowledge about current transformers

A current transformer produces an alternating current in the secondary that is proportional to the current in the primary. By having a known turns ratio, the currents in the primary and secondary are connect, and if the current in the secondary is measure, the current flowing in the primary can be determine.

Typically, a current transformer primary will be design to handle large currents, i.e. the full current of the primary circuit used to measure the current. Therefore, the primary can be a single turn or a heavy duty coil. It can even be a single wire running through the center of the transformer core.

Since the current transformer is in series with the load in the primary circuit, these transformers are sometimes call

“series transformers”.

The secondary will have a larger number of turns so it can produce a large enough current for easy measurement.

Typically the core can be a laminated core of low loss magnetic material, or a toroidal transformer is also popular. Regardless of the exact format, the core has a large cross-sectional area and therefore produces a low flux density. This enables the transformer to output a constant current that is as independent as possible of the connected load.

Current transformers can come in many forms:

Toroidal Transformers: Toroidal transformers are very popular in many applications. These transformers tend to have a secondary winding around the former in the normal way, but the main wire being sense runs directly through the center of the toroid.

Traditional Wire Wound Transformer: Another form of popular current transformer is the wire wound transformer. This type of transformer is available from electronic component distributors and manufacturers, and many manufacturers carry multiple types. These are often integrate into electronic systems where the transformer is a permanent electronic component and an integral part of the design.

Bar Transformer: This type of transformer is often associated with high current applications where a bar is required for high current levels. The cable or busbar of the main circuit serves as the primary winding, which is actually a single turn. Auxiliary wrapped around it.