The Siemens 5SJ6120-7FC is a 1-pole miniature circuit breaker with a C-trip curve, rated at 20 A and a 6 kA interrupting capacity. This is a standard DIN-rail mount MCB for branch-circuit protection in distribution boards and control panels — the C-curve (5–10× In) handles moderate inrush from motor starters, small transformers, or lighting ballasts without nuisance tripping, while still clearing short-circuit faults up to 6 kA.
Snaps onto standard 35 mm DIN rail per EN 60715. The 1-pole width (1 module = 18 mm) fits tight panel layouts. Rated for 50/60 Hz networks up to 240/415 VAC. Terminal design accepts up to 25 mm² conductor — common for the 20 A feed-through in a sub-distribution board. No external arc-quench clearance needed beyond the standard DIN-rail spacing.
The C-curve characteristic means the magnetic trip activates between 5 and 10 times the rated current (100–200 A for this 20 A unit). That suits it for general-purpose resistive and moderate inductive loads where the inrush peak stays under that band. For highly capacitive loads or long cable runs, verify the peak inrush against the C-curve threshold to avoid coordination issues downstream.