How should a current transformer be connected within a circuit?

A current transformer (CT) is designed to measure alternating current (AC) and typically produces a secondary current that is proportional to the current flowing through its primary winding. To ensure accurate operation and safe measurements, a current transformer must be connected in series with the load or the conductor being measured.

When connected in series, the CT interfaces with the current flowing through the primary side, allowing it to produce a scaled-down version of that current on the secondary side. This configuration is essential for ensuring that the CT accurately reflects the current in the circuit, enabling proper monitoring and measurement.

If the CT were connected directly to ground, in parallel, or in combination inappropriately, it would not function as intended, potentially leading to inaccurate readings or even dangerous conditions due to improper loading and voltage surge exposure. Consequently, connecting current transformers in series is foundational to their correct operation in any electrical measurement system.