How core balance current transformer works

News | company news | Jan 20,2024

Working principle of core balanced current transformer

A Core Balance Current Transformer (CBCT) is a type of current transformer design to measure the current flowing in an electrical power system. Its main function is to provide a current signal proportional to the primary current flowing through the conductor surround by the CBCT. The following is a basic description of how core balance current transformers work:

Core design:

CBCT consists of a toroidal (ring-shaped) magnetic core made of a high permeability material, such as iron or ferrite compounds.
The core has a primary winding, which is usually place around the entire circumference of the core and surrounds the conductor that carries the primary current.

Primary current:

The primary current, the current to be measure, flows through the conductor surround by the CBCT.
The primary winding on the CBCT is in series with the primary conductor.

Magnetic flux induction:

When primary current flows through a conductor, magnetic flux is induce in the core due to the principle of electromagnetic induction.
The core ensures that most of the magnetic flux generate by the primary current is confine within it.

Secondary winding:

The CBCT has a secondary winding that is usually connecte to a measuring instrument or protective relay.
The secondary winding is wound on the same magnetic core but is electrically isolate from the primary winding.

Current transformation:

The magnetic flux induced by the primary current is also connect to the secondary winding, causing an electromotive force (EMF) to be induce in the secondary winding.
The induced voltage in the secondary winding is proportional to the primary current and serves as a representation of the primary current.

Isolation and measurement:

The secondary winding provides electrical isolation between the primary current and the measuring instrument.
The secondary current is then use for measurement, monitoring or protection purposes.

Core Balance Principles:

The term “core balancing” comes from the fact that the CBCT is design to maintain a balance between the primary current and the magnetic flux induce in the secondary winding.
This design makes the CBCT very sensitive to the vector sum of currents flowing through the conductors within the core, making it particularly useful for ground fault detection.

In summary, core-balanced current transformers are important components in power systems for accurate and isolated current measurements, especially in applications where ground fault detection is critical.