What this MCCB is and what it does
The Siemens SENTRON 3VA1112-3EF32-0CC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a TM240 thermal-magnetic trip unit. Its 125 A rated continuous current Iu holds flat from 40 °C through 50 °C, then derates to 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C — so if your panel ambient runs above 50 °C, size the breaker for the derated figure, not the nameplate. Interrupting capacity varies with line voltage: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 10.5 kA at 690 V. That gives you selectivity headroom at the common 415 V industrial level — the 52.5 kA figure lets it coordinate downstream of a larger upstream device without needing a current-limiting fuse ahead of it in most plant distributions. Rated insulation voltage Ui is 800 V, so the breaker is electrically rated for 690 V line-to-line service with margin. The front carries IP40 protection — fine for a clean indoor panel, but not for washdown areas or dust-heavy environments.
Auxiliaries and releases fitted from the factory
This unit ships with an undervoltage release (UVR) integrated — design code 3VA9608-0BB24 — and two auxiliary switches (HQ type). The UVR means the breaker trips on loss of control voltage; if your safety circuit expects a shunt trip or you need a separate undervoltage coil, this has it built in. No communication module, no ground-fault monitoring, no phase-failure detection on this variant — it is a straight thermal-magnetic line-protection breaker with undervoltage supervision. Mechanical endurance is rated at 15 000 cycles — typical for a 125 A frame in distribution duty; not a high-cycling motor-switching MCCB, but fine for infrequent manual or remote switching in a feeder panel.
Panel fit and footprint
Dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a standard 3-pole SENTRON 3VA frame that drops into existing DIN-rail or screw-mount panel layouts without re-drilling. The 70 mm depth is shallow enough for 200 mm deep enclosures; leaves room behind the gland plate for wiring and the UVR coil connections. Storage range is -40 °C to 80 °C; operating range -25 °C to 70 °C. The storage bottom end matters if the breaker sits in an unheated warehouse before commissioning — it can take the cold without damage.