What this MCCB is and what it does
The Siemens SENTRON 3VA1112-4EF32-0AE0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a TM240 thermal-magnetic overcurrent release. At 40 °C through 50 °C it holds a continuous current rating of 125 A without derating, then steps down to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C — so the thermal curve starts biting above 50 °C, not before. The 125 A figure is the one to use for panel sizing in a ventilated enclosure below 50 °C ambient.
Breaking capacity — what it means for fault clearance
Rated ultimate breaking capacity (Icu) varies by system voltage: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. At 415 V — the most common industrial distribution voltage outside North America — 75.6 kA gives generous headroom above a typical 50 kA or 65 kA service entrance requirement. At 690 V the 11.9 kA figure is adequate for motor branch circuits but not for a main breaker on a high-fault transformer. The 800 V rated insulation voltage confirms the 690 V rating is legitimate, not a derated 400 V design pushed upward.
Panel fit and integration notes
Dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a compact 3-pole MCCB footprint that fits standard Siemens 3VA mounting accessories and busbar systems. The 28.1 W maximum power loss at rated load matters for thermal coordination inside a sealed enclosure; that heat has to be moved, so factor it into the cabinet's dissipation budget. The auxiliary switch design accommodates up to 4 HQ auxiliary switches, though this unit ships without them fitted. No undervoltage release, no ground-fault monitoring, no communication function — it is a plain line-protection breaker, not a smart or adjustable-trip device.