What this MCCB is and what the ratings mean for fit
The Siemens SENTRON 3VA1120-6MH32-0AA0 is a 3-pole molded case circuit breaker (MCCB) designed specifically for starter protection — meaning it is built to protect motor starters and their associated control circuits, not general distribution feeders. Its TM120M thermal-magnetic overcurrent release provides inverse-time overload protection plus instantaneous short-circuit trip, sized for a 20 A continuous load at 40 °C through 55 °C; at 60 °C it derates to 19 A, holding to 19 A through 70 °C. The headline breaking capacity is 220 kA at 240 VAC, dropping to 154 kA at 415 VAC, 121 kA at 440 VAC, and 7.5 kA at both 500 VAC and 690 VAC — so at higher line voltages the interrupting capability falls sharply, and the 7.5 kA figure at 500/690 V is the one that governs coordination in a 480/600 V panel. Rated insulation voltage is 800 V, and maximum power loss is 12 W.
Where it is used and how it mounts
This MCCB is intended for panel or enclosure mounting in motor control centers, starter assemblies, and industrial control panels where the breaker protects a motor starter branch. It occupies a 76.2 mm wide by 130 mm tall by 70 mm deep footprint (3 in × 5.12 in × 2.76 in). The front face carries an IP40 protection class rating, so it is suited for dry indoor environments but not washdown or outdoor exposure. The design is for fixed mounting — not a plug-in base — so panel cutouts and bus connections must be planned for this specific frame size.