What this MCCB is and what it does
The Siemens 3VA1120-6MH36-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed specifically for starter protection — meaning it is built to protect motor starters and their associated wiring, not just general distribution circuits. Its TM120M thermal-magnetic overcurrent release provides inverse-time overload protection and instantaneous short-circuit response, sized for a 20 A continuous load at 40 °C ambient (derated to 19 A at 70 °C). The 220 kA breaking capacity at 240 VAC gives it the headroom to interrupt high-fault currents on industrial motor branches without cascading upstream.
Breaking capacity and selectivity
This MCCB carries a 220 kA interrupting rating at 240 VAC, dropping to 154 kA at 415 VAC and 121 kA at 440 VAC — figures that suit it for high-available-fault installations like large motor control centers or transformer-fed switchboards. At 500 V and 690 V the rating settles to 7.5 kA, which still covers most low-voltage motor branch circuits. The 800 V rated insulation voltage (Ui) confirms the internal clearance and creepage for 690 V line-to-line systems.
Physical fit and panel integration
The 3VA1120-6MH36-0AA0 measures 70 mm deep, 76.2 mm wide, and 130 mm tall — a 3-pole footprint that fits standard Siemens SENTRON mounting bases and panel cutouts. No DIN-rail clip is specified; these MCCBs typically bolt directly to a busbar or mounting plate. The 12 W maximum power loss should be factored into enclosure thermal calculations, especially in sealed cabinets with multiple breakers.