The Siemens 5SL4340-7 is a SENTRON miniature circuit breaker — 3-pole, C-curve, rated 40 A at 400 V AC, with a 10 kA breaking capacity certified to both EN 60898 and IEC 60947-2. The 3-pole design handles three-phase loads up to 440 V AC (multi-phase operation), and it also carries a DC rating of 72 V maximum — useful if the same panel feeds a DC bus or control supply, though the DC breaking capacity is not the same as the AC 10 kA figure.
Panel integration and physical fit
The 5SL4340-7 occupies 3 modular width units (each 18 mm, so 54 mm total) on a DIN rail. The 90 mm height is standard for SENTRON MCBs, so it aligns with adjacent devices in a multi-row enclosure. It is sealable (a lead seal can be fitted through the toggle slot to prevent unauthorized switching), halogen-free and silicon-free — important for environments where outgassing from a fault could damage sensitive electronics or contaminate clean-room processes.
The closest peer in the same family is the 5SL4363-7 — identical form factor (same 54 mm width, 76 mm depth, 90 mm height), same 3-pole C-curve, same 10 kA breaking capacity, same 400 V AC rating. The difference is the current rating: the 5SL4363-7 is a 63 A device. If your BOM specifies 40 A, the 5SL4340-7 is the correct part; the 63 A version will not drop in without checking the downstream conductor sizing and load protection coordination.
The halogen-free and silicon-free construction supports RoHS and REACH compliance. The manufacturer provides a declaration of conformity and test reports; these are typically available on the Siemens Industry Online Support portal.