What this MCCB is and what it does
The Siemens 3VA1120-3EF46-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. Its four poles and 20 A rating at 40 °C make it a standard fit for feeder circuits in commercial and light industrial switchboards. The TM240 overcurrent release is a thermal-magnetic type — the thermal element handles overloads, the magnetic element handles short-circuits. No undervoltage release or communication function is built in, so it's a straight electromechanical protector with no auxiliary electronics to fail. Breaking capacity is 75.6 kA at 240 V, 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 figure at 240 V means it can safely interrupt a fault current up to that level without welding contacts or cascading upstream — important for high-fault-capacity services near transformers.
Panel fit and thermal derating
Dimensions are 70 mm deep, 101.6 mm wide, 130 mm high. The 4-pole width at roughly 100 mm is standard for a 4-pole MCCB in a DIN-rail or backplate layout — plan for that footprint when laying out gland plates and busbar runs. Rated 20 A continuously at 40 °C, and holds that rating through 55 °C. At 60 °C it derates to 19 A, and stays at 19 A through 70 °C. That gives a solid thermal margin in a warm enclosure; you don't lose headroom until the ambient exceeds 55 °C. Front IP40 protection means it's sealed against tools and small wires but not against water spray — keep it inside the panel, not on a washdown-zone door.
Lifecycle and sourcing posture
Insulation voltage rated at 800 V, power loss 12 W max. Storage range -40 °C to 80 °C, operating range -25 °C to 70 °C. These are standard industrial specs — no special handling or climate-controlled storage needed.