Siemens 5SY7232-7 SENTRON MCB — 2-pole C-curve, 15/25 kA
The Siemens 5SY7232-7 is a 2-pole miniature circuit breaker from the SENTRON series, with a C tripping characteristic. It is rated for 400 V AC and carries a breaking capacity of 15 kA per EN 60898-1 and 25 kA per IEC 60947-2, with a DC rating of 15 kA at 60 V per IEC 60947-2. For UL 1077 / CSA C22.2 No. 235 applications, the interrupting rating is 5 kA. The 36 mm width (2 modular units) snaps onto a DIN rail — standard panel integration for a 2-pole MCB. The C-curve (5–10× In) is the go-to for general industrial loads: motor control circuits, small transformers, and lighting banks where moderate inrush is expected.
Breaking capacity and selectivity headroom
The dual rating matters for panel design. At 15 kA (EN 60898) the breaker is tested for domestic/similar installations; the 25 kA (IEC 60947-2) rating is the industrial figure — it tells you the device can interrupt fault currents up to that level without welding contacts or cascading failure upstream. The DC rating of 15 kA at 60 V covers control-circuit DC supplies common in industrial panels. The UL 1077 listing at 5 kA is the supplementary protector rating for North American panels — not a branch-circuit rating, but sufficient for most control-transformer and PLC supply protection. If you are coordinating with an upstream 25 kA-rated main breaker, this holds selectivity down to the sub-feed.
Mounting and environmental fit
Snap-on mounting to DIN rail, any position. Depth is 76 mm (installation depth 70 mm), width 36 mm (2 MW), height 90 mm. IP20 with conductors connected — standard for enclosed panel use. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive with condensation — typical for industrial control rooms). Ambient range -40 °C to 75 °C, with humidity derating: max 95% RH at 55 °C, 55% at 70 °C, 35% at 75 °C. Halogen-free and silicon-free construction — relevant for environments sensitive to outgassing (clean rooms, certain chemical plants). Sealable terminals allow lockout/tagout. Combined top and bottom terminals simplify busbar or ring-tongue wiring.