When high currents need to be recorded and processed, plug-in current transformer are used. The conductor to be measured (busbar or cable) is fed through the window opening and forms the primary circuit of the plug-in current transformer.
Current transformer are mainly used for mounting on busbars. Drop resistance is achieved through additional encapsulation as well as higher shock and vibration resistance under mechanical stress (IEC 68). This is the most common and most cost-effective type of current transformer, but the primary conductor must be interrupted during installation. In other words, this type of transformer is mainly used for new installations.
