The Siemens 3NJ6304-1AB0.-.... is a SENTRON 3NJ63 switch disconnector with fuses in an in-line design. It takes NH00 fuse links rated up to 160 A across four poles, switching at AC23B duty up to 500 V. Built-in EFM 10 electronic fuse monitoring gives a signal output when a fuse blows, so a line-side fault doesn't sit silent until the next shift finds the dead machine. That alone saves hours of fault isolation on a multi-drop distribution board. Rated AC23B means it handles mixed motor and resistive loads — switching motors, heaters, and transformer primaries under occasional overload. Not a pure disconnect for transformer-only duty (AC20/21); this one is specced for the tougher switching cycles.
Panel-fit and compliance notes
In-line design — the line and load terminals are on opposite ends, so it fits a straight busbar run or a panel where the feed enters top-left and exits bottom-right. No right-angle or rear-connection surprises. RoHS compliant since 27 September 2019. REACH Article 33 candidate-list disclosure is available from the manufacturer.