How many types are the current transformers classified into?

Current transformers are classified into five primary types based on their application and construction:

1. Wound Type Current Transformer: In this type, the primary winding comprises one or more turns of heavy copper wire and is directly connected in series with the circuit that requires monitoring or control.

2. Ring Type or Window Type Current Transformer: This type does not have a primary winding. Instead, the line that carries the current flowing in the network is threaded through a window or a ring forming a single turn primary winding.

3. Bar-Type Current Transformer: Here, the transformer is constructed with the secondary winding wrapped around an iron core which is solidly fixed in the housing of the transformer. The bar itself acts as the primary winding.

4. Toroidal (Ring) Current Transformer: These transformers do not have a primary winding. Instead, the line that needs to be monitored is passed through a ring-shaped core directly. They are known for their accuracy at lower current levels.

5. Tap or Split-Core Type Current Transformer: This type of transformer provides a convenient way to install the transformer without disconnecting the circuit that it monitors. It can be “opened” and installed over a conductor within the circuit.

These classifications are based on functionality, application, and the design of the primary winding. Each type is chosen based on the specific needs of the measurement or protection system it is to be used with.