The Siemens 5SM9343-6 is a SENTRON residual current (RC) unit designed to pair with a 5SL4 miniature circuit breaker, forming a combined RCD/MCB assembly for 4-pole (3P+N) circuits. It is rated for 40 A continuous current and a 30 mA trip threshold, type A (pulsating DC and sinusoidal AC sensitive), at 400 V AC supply voltage. Type A detection means it catches both sinusoidal AC faults and pulsating DC faults up to 6 mA smooth DC superimposed — the kind a variable-speed drive or LED driver can generate. If your load includes single-phase rectifiers, you need type A, not type AC.
Rated at 40 A and 400 V AC, this RC unit matches a 40 A 4-pole 5SL4 MCB. The 30 mA trip handles the leakage path to earth. Installation depth is 70 mm. Mounting position is unrestricted, so it can sit horizontally or inverted in a tight enclosure — useful when you're packing a sub-distribution board.
Integration and deployment
This is an electronic RC unit designed to clip onto the load side of a 5SL4 miniature circuit breaker. The supply feeds in at the top, above the MCB. It is not a standalone RCD — it requires the matching 5SL4 breaker to provide overcurrent and short-circuit protection. The assembly saves one module width compared to separate RCD + MCB units. The unit is instantaneous (no short-time delay), so it trips immediately on fault — not suitable for selective coordination with downstream RCDs.
The 5SM9343-6 carries a current lifecycle status from Siemens, meaning it remains in the active catalog for new designs and replacement orders. No phase-out or last-time-buy notice is associated with this order code.