How do three-phase current transformers work?

News | | Jan 25,2024

Some knowledge about the three-phase current transformer in one

Three-phase current transformers are similar to single-phase current transformers, but are suitable for three-phase power systems and can measure three-phase currents.
Common in power systems is three-phase alternating current, in which the transformer has three phases, usually labeled A-phase, B-phase and C-phase. Three-phase current transformers are use to measure the current in these three phases. In order to measure the current of each phase, a three-phase current transformer usually consists of three single-phase current transformers, each transformer is responsible for measuring the current of one phase. These three transformers can be install in a power system in a specific arrangement. Our common connection methods include star connection and delta connection.
The working principle of a three-phase current transformer is similar to that of a single mutual inductor. When current passes through the wires of the primary winding, a magnetic field is create in the secondary winding of the transformer. This magnetic field is induce into the secondary winding, producing an induced electromotive force. Since phase differences exist in a three-phase system, the phase relationship of the currents measure by each transformer must also be considere. The measurement results need to be properly process to reflect the relative relationship between the phases in the power system. Like a single transformer, a three-phase current transformer has a ratio that represents the relationship between the primary winding current and the secondary winding current.
Generally speaking, three-phase current transformers use the principle of electromagnetic induction to convert three-phase currents into smaller currents that can be measure and process, thereby playing a role in measurement and protection in three-phase power systems. Different arrangements and phase handling methods can be adapted to different types of three-phase systems.

--- END ---

Prev: How core balance current transformer works

Next: What are the applications for open current transformers?