Use a plastic-case current transformer if you want to record and process high currents. The line to be measured (conductive rail or wire) is fed through the window and forms the primary circuit of the plug-in current transformer. Plastic-case current transformers are mainly installed on conductive rails. With additional potting, water drop tightness can be achieved, as well as shock and vibration resistance under mechanical load (IEC 68). This is a common and cost-effective form of current transformer. However, the primary conductor must be disconnected during installation. Therefore, this form of transformer is often used in new system installation.