What this MCCB is and what it does
The Siemens SENTRON 3VA1020-3ED32-0JA0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection — the primary feeder or distribution circuit, not a motor-protective device. It carries a continuous current rating of 20 A across the 40 °C to 55 °C ambient range, derating to 19 A at 60 °C through 70 °C. The TM210 overcurrent release combines a thermal bimetal for overload protection and a magnetic coil for short-circuit response; the fixed thermal element is calibrated for the 20 A frame. The interrupting capacity is what defines this breaker's fault-clearing capability: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at both 500 V and 690 V. For a 20 A frame, those numbers are high — this is a high-interrupting variant intended for installations with substantial available fault current, such as large panelboards or transformer secondaries where a standard 10 kA or 18 kA MCCB would not hold. The shunt trip (STL) auxiliary release allows remote tripping via a control voltage. Insulation voltage is rated 800 V. Power loss at rated current is 12 W maximum.
Physical fit and panel integration
The breaker measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard 3-pole MCCB footprint that mounts on a DIN rail or directly to a mounting plate. The 76.2 mm width (3 inches) is the critical dimension for multi-pole grouping in a panel: three poles occupy roughly 3 inches of rail space. Depth of 70 mm (2.76 in) leaves clearance for rear-connected bus bars or cable lugs. Operating temperature range is -25 °C to +70 °C, storage from -40 °C to +80 °C. The 12 W power loss at full load should be factored into enclosure thermal calculations — in a sealed panel with multiple breakers, that heat adds up.
Key ratings at a glance
Rated current: 20 A (continuous at 40–55 °C ambient). Poles: 3. Interrupting capacity: 75.6 kA at 240 V AC, 52.5 kA at 415 V, 32 kA at 440 V, 7.5 kA at 500 V and 690 V. Overcurrent release: TM210 thermal-magnetic, fixed. Auxiliary release: shunt trip (STL). Insulation voltage: 800 V. Power loss: 12 W max. No undervoltage release, no ground-fault monitoring, no communication function, no trip indicator.