Siemens 3VA1120-5EF32-0AA0 — SENTRON MCCB, 20 A, 187 kA at 240 V
The Siemens 3VA1120-5EF32-0AA0 is a 3-pole SENTRON molded case circuit breaker rated for 20 A continuous at 40 °C, with a TM240 thermal-magnetic release and a maximum breaking capacity of 187 kA at 240 VAC. The 187 kA interrupting rating at 240 V means this breaker can safely clear a fault current up to that level without welding contacts or rupturing the case — critical for high-fault panels near large transformers or utility feeds. At 415 V the breaking capacity is 121 kA; at 440 V it drops to 75.6 kA, and at 500 V or 690 V it holds at 17 kA — the SCCR headroom shrinks with voltage, so verify your system's available fault current at the point of installation. The TM240 release combines a thermal bimetal for overload protection (trip curve shaped to motor or feeder inrush) with a magnetic short-circuit element adjustable up to 320 A (li max) for selective coordination downstream. Rated insulation voltage is 800 V, and the breaker accepts up to 500 V DC — useful for DC bus or battery-string protection where a standard AC-only MCCB won't hold. Front IP40 rating means it's protected against tools and wires >1 mm, but not sealed against washdown — mount inside a panel or enclosure if the environment is wet or dusty.
Sizing and thermal derating
The 20 A rating holds flat from 40 °C through 55 °C — no derating needed in a warm panel up to that point. At 60 °C it drops to 19 A, and at 70 °C it's still 19 A, so a 20 A load in a 60 °C ambient requires a frame size up. Maximum power loss is 12 W at rated current — negligible for panel thermal budgeting, but worth noting if several breakers cluster in a small enclosure without forced ventilation. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C — the storage limit governs handling and warehousing, not running conditions.
Physical fit and panel integration
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — a compact 3-pole frame that fits standard 3-inch-wide panel cutouts and leaves room for side-by-side mounting on a DIN rail or direct screw-mount plate. The 76.2 mm (3 in) width matches the typical SENTRON 3VA1 frame footprint, so it drops into existing panel layouts without re-drilling or bus-bar rework. Optional motor drive (Product Extension / Optional / Motor Drive: Yes) allows remote motorized operation for automated disconnection or reset in unmanned substations.
Lifecycle and sourcing
No communication function, no ground-fault monitoring, and no other measurement function are built in. The IEC 81346-2 reference code is Q (switching device), which aligns with standard panel labeling conventions for circuit breakers in industrial schematics.