32 A MCCB with 121 kA interrupting — what the ratings mean for your panel
The Siemens 3VA1132-4EF32-0HH0 is a SENTRON molded case circuit breaker (MCCB) sized for 32 A line protection duty. The 121 kA interrupting capacity at 240 V AC means this breaker can safely clear a fault up to that level without welding contacts or cascading failure upstream — critical for high-fault panels near large transformers or parallel utility feeds. The TM240 thermal-magnetic release provides inverse-time overload protection and instantaneous short-circuit trip, a workhorse combination for feeder and distribution circuits where ground-fault monitoring isn't required.
Derating curve and thermal management
Rated continuous current holds at 32 A from 40 °C through 50 °C ambient. Above that, it steps down: 30.72 A at 55 °C, 30.08 A at 60 °C, 29.44 A at 65 °C, and 28.8 A at 70 °C. In a sealed panel or high-ambient enclosure, that 55 °C threshold is the first one to watch — a 4 % derating from nominal means the breaker is still usable for a 30 A continuous load but not a full 32 A feeder. The 15000 mechanical/electrical endurance cycles (latching) suit the breaker for frequent-switching applications like capacitor bank or lighting contactor panels.
Interrupting capacity across voltage tiers
The interrupting capacity drops as system voltage rises: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. For 400 V-class distribution panels common in European and Asian industrial plants, the 75.6 kA figure provides ample headroom for most transformer-fed installations. The 690 V rating of 11.9 kA limits this breaker to lower-fault 690 V applications — verify the prospective short-circuit current at the point of installation before committing the BOM.
Auxiliary contacts and shunt trip — the integrated trip alarm
The breaker ships with 2 auxiliary switches plus 1 trip alarm switch (HQ configuration) and a shunt trip release (STL) for remote tripping. The integrated auxiliary trip order code 3VA9688-0BL30 is the companion accessory for the shunt trip coil. The trip indicator (mechanical flag) and voltage trigger confirm the breaker state locally. No communication module, undervoltage release, or phase failure detection is built in — this is a pure line-protection device, not a smart breaker.
Dimensions and panel integration
Front-face dimensions: 130 mm height by 76.2 mm width, 70 mm depth behind the panel. The 76.2 mm width matches the standard 3-pole MCCB footprint on a DIN-rail or direct-mount backplate. IP40 on the front face means the breaker is protected against tools and wires >1 mm — standard for enclosed panel mounting, not for wet or dusty environments.