3-pole C-curve MCB for 400 V AC distribution
The Siemens 5SN6303-8CP is a 3-pole miniature circuit breaker from the SENTRON 5SN series, rated for 400 V AC at 50 Hz with a C-curve tripping characteristic. The 72 V DC maximum rating means it can also protect DC control circuits up to that voltage, though the primary application is AC branch circuit protection.
The dual breaking capacity rating is the key spec for a site electrical engineer coordinating a panel. The 30 kA per IEC 60947-2 gives headroom for industrial distribution where upstream transformers can deliver higher fault current — this MCB can be applied downstream of a 30 kA-rated main breaker without cascading failure, provided the let-through energy is coordinated.
Accepts solid conductors up to 35 mm². Ambient range -40 to 75 °C. Power loss 1.2 W per pole.