Current Transformers

Current transformers or (CT’s), also known as Core Balance Current Transformers or Current Transducers, are instruments that are used to reduce or multiply the current from a high current into a lower current or vice versa. This is done so that the power can then be easily managed by Relays and measurement tools for electrical circuits and processes. Current Transformers consist of a core, a primary and a secondary winding.

RS offer an extensive range of highly accurate Core Balance Current Transformers in various transformer types, current ratings, CT ratio supply voltages and mounting types to suit every application. Supplied by industry-leading brands including Siemens, Murata Power Solutions LEM and of course RS PRO.

How does a current transformer work?

When an alternating current flows through the primary winding, a magnetic flux is created which then induces an alternating current in the secondary winding. This alternating current is proportional to the current in its primary. Current transformers are also known as a “step-down transformer”. Once the current has been reduced it can be safely monitored and measured using an Ammeters

Types of current transformer

Toroidal Current Transformer

These transformers are shaped like a doughnut they do not contain a primary winding. Instead, the line that carries the current flowing in the network is threaded through a window or hole in the toroidal transformer. Toroidal transformers offer high efficiency with minimal excess noise and little excess leakage inductance.

Wound Current Transformer

-The transformers primary winding is physically connected in series with the conductor that carries the measured current flowing in the circuit. The magnitude of the secondary current is dependent on the turn’s ratio of the transformer.

Bar-type Current Transformer

– This type of current transformer uses the actual cable or bus-bar of the main circuit as the primary winding, which is equivalent to a single turn. They are fully insulated from the high operating voltage of the system and are usually bolted to the current-carrying device.