It is an external neutral current transformer (ENCT) for ComPacT NSX400 to NSX630 equipped with MicroLogic 5/6 trip unit. With 3P devices, the distributed neutral of the installation can be protected by installing this external sensor. The sensor rated current is from 400A to 630A. The ENCT must be connected to the MicroLogic trip unit by a shielded twisted pair. The wiring maximum length is 10 m and the cross section is from 0.4 mm² to 1.5 mm².