What this MCCB is and where it fits
The Siemens SENTRON 3VA1225-5GF42-0BC0 is a 4-pole molded case circuit breaker (MCCB) rated for 250 A continuous current, built for line protection in distribution panels and motor control centers. It carries a TM240 thermal-magnetic overcurrent release — the thermal element handles overloads, the magnetic element clears short circuits — and it ships with a factory-integrated undervoltage release (UVR) plus two high-quality auxiliary switches (3VA9608-0BB11). The 140 mm width and 70 mm depth fit standard Siemens 3VA panel footprints; the IP40 front rating means it's fine inside a clean indoor enclosure but not for washdown areas. Breaking capacity is the headline spec here: 187 kA at 240 V AC, 121 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. That 187 kA figure at 240 V means this breaker can safely interrupt a fault current up to 187,000 amps without welding its contacts or rupturing the case — critical for high-fault locations like transformer secondaries or large motor banks. The 121 kA at 415 V is the figure most European panel designers will check first; it's well above typical utility fault levels, so you get full selectivity without cascading upstream.
Thermal derating — what 250 A actually means at panel temperature
The 250 A rated continuous current (Iu) holds flat from 40 °C through 50 °C ambient — no derating needed in most ventilated enclosures. Above that, the curve is gentle: 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If your panel runs hot — say a packed MCC with multiple breakers — size the load at the 55 °C or 60 °C figure, not the nameplate 250 A. The operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C.
What's in the box — auxiliary contacts and releases
This variant comes with two factory-fitted auxiliary switches (designated HQ — high-quality, typically gold-plated contacts for signal reliability at low loads) and an undervoltage release (UVR) that trips the breaker when control voltage drops below a threshold. The auxiliary contact order code is 3VA9608-0BB11 if you need a spare or want to match it on a panel build. No communication module, no ground-fault monitoring, no voltage trigger — this is a straight line-protection breaker with the UVR as the only add-on. The N-conductor protection is set to 100% (full-rated), meaning the neutral pole carries the same current rating as the phases.