What it is and what it does
The Siemens 3VA1112-3ED46-0AA0 is a SENTRON molded case circuit breaker (MCCB) for line protection — the main disconnect and fault protection in a distribution panel, switchboard, or motor control center. It's a 4-pole unit rated 125 A continuous at 40 °C ambient, with a TM210 thermal-magnetic trip unit. The TM210 means fixed thermal and magnetic settings; no interchangeable trip modules, no adjustment dials. You set it, you lock it, you move on. Breaking capacity is the headline number here: 75.6 kA at 240 V AC, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That 75.6 kA at 240 V tells you it's built for high-fault locations — close to a transformer or on a large bus where the available fault current is substantial. At 690 V it still clears 11.9 kA, which covers most industrial motor loads. Rated insulation voltage is 800 V, and max DC operational voltage is 600 V — so it can be used on DC circuits up to that level, though the DC breaking capacity isn't listed here and would need a manual check. The front face carries IP40 protection, meaning it's protected against tools and wires >1 mm but not against water ingress — standard for a panel-mounted breaker.
Sizing and thermal performance
The 125 A rating holds flat from 40 °C to 50 °C — no derating needed in a warm panel. At 55 °C it drops to 122 A, at 60 °C to 120 A, at 65 °C to 117 A, and at 70 °C to 114 A. If your enclosure runs hot, you lose about 1 A per degree above 50 °C. That's predictable and easy to factor into the wire and bus sizing. Maximum power loss is 28.1 W. That's the heat the breaker dumps into the enclosure at full rated current. For a multi-breaker panel, that heat adds up — account for it in the ventilation or cooling calculation.
Physical fit and mounting
Dimensions: 130 mm tall, 101.6 mm wide, 70 mm deep. The 4-pole width is about 4 inches — standard for a 4-pole MCCB in this class. Depth of 70 mm (2.76 in) is shallow enough for most 200 mm deep enclosures, leaving room for wiring gutters. Mounting is via the rear panel or a DIN rail adapter (not included). The IP40 front face is fine for a closed panel; if the door is open for commissioning, treat it as unprotected.
Compliance and documentation
The reference code per IEC 81346-2 is Q (switching device). The breaker is designed for line protection, not for ground-fault monitoring (no GF version) and without N-conductor protection. A motor drive option is available as a product extension. Full compliance documentation — RoHS, REACH, UL, IEC — is provided by Siemens with the device. The manual for DC applications is available separately under Service & Support.