What this MCCB carries
The Siemens SENTRON 3VA1112-4EF36-0JH0 is a 3-pole molded case circuit breaker rated 125 A continuously at 40 °C, with an interrupting capacity of 121 kA at 240 VAC. That 121 kA figure means it can safely clear a fault at that level without upstream cascading — critical for high-fault service entrances or transformer secondaries where available fault current is high. The breaker is designed for line protection, not motor or feeder protection, so it is sized for the main or submain bus, not a specific load curve.
Ratings and what they mean for fit
At 415 V the interrupting rating drops to 75.6 kA, at 440 V to 52.5 kA, and at 500 V and 690 V to 11.9 kA. The thermal continuous rating holds at 125 A from 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. This derating curve matters if the breaker sits in a warm enclosure or next to other heat sources — the 125 A nameplate only applies up to 50 °C ambient. Insulation voltage is rated 800 V, so the breaker is suitable for 480/277 V and 600 V systems within the interrupting limits.
Auxiliary and release configuration
This variant ships with 2 auxiliary switches plus 1 trip alarm switch (HQ configuration), and a shunt trip release (STL) for remote tripping. There is no undervoltage release, no ground-fault monitoring, and no communication function. The auxiliary switch count is enough for status feedback to a PLC or a remote annunciator — one NO/NC pair for breaker position, one for trip indication. The shunt trip allows a safety relay or E-stop circuit to open the breaker remotely, which is common in emergency-off circuits where the MCCB serves the main disconnect.
Physical fit and panel integration
The breaker measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard SENTRON 3VA frame size that mounts on a DIN rail or panel-mount adapter. The 76.2 mm width (3 inches) is the standard 3-pole MCCB footprint for this series, so it drops into existing 3VA panel layouts without re-drilling. Operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C. Maximum power loss is 28.1 W, which should be factored into enclosure thermal calculations.