The Siemens 3NJ6302-3AA0.-.... is a SENTRON 3NJ63 switch disconnector with fuses, built in an in-line design for DC circuits. It accepts pluggable NH00 fuse links up to 160 A and is rated for DC-23B duty at 230 V with a breaking capacity of 100 kA — meaning it can safely interrupt fault currents up to that level in a DC-23B load circuit (switching of resistive and mixed resistive-inductive loads including moderate overloads). This is the part to specify when you need a fused disconnect for a DC bus, battery bank, or DC distribution panel where the interrupting rating must match the available fault current.
Product class C means this unit is manufactured to order and cannot be returned or reused — confirm your BOM line before committing. Panel builders should note the in-line design and NH00 fuse footprint; the 2-pole DC construction suits positive/negative or two-wire DC circuits. Verify the mounting arrangement against your enclosure cutout and busbar spacing.