What this MCCB is and what it does
The Siemens 3VA1120-6EF32-0JH0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in power distribution panels. It carries a 20 A rated current across the 40 °C to 55 °C ambient range, derating to 19 A at 60 °C and above — so in a warm enclosure you lose 1 A, not a full trip curve shift. The 3-pole construction handles three-phase circuits up to 800 V insulation voltage (rated value). Breaking capacity is the headline here: 220 kA at 240 V AC, 154 kA at 415 V, 121 kA at 440 V, and it still holds 17 kA at 500 V and 690 V. That means it can interrupt very high fault currents on the secondary side of a large transformer without needing an upstream current-limiting fuse — useful for high-SCCR panel designs where the available fault current exceeds 100 kA.
Switching and accessory fit
This variant ships with a shunt trip (STL) for remote tripping and a complement of two auxiliary switches plus one trip alarm switch (HQ) — so it can signal position and fault status back to a PLC or annunciator without an add-on module. No undervoltage release, no ground-fault monitoring, no communication function; it is a straight line-protection MCCB with remote-trip capability. The basic switch designation is 3VA11206EF320AA0; the order code suffix -0JH0 adds the shunt trip and the auxiliary switch configuration. Panel builders should note the 12 W maximum power loss at rated load — that heat has to be considered in the enclosure thermal budget, especially in a high-density panel.
Dimensions and panel fit
The MCCB measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard 3-pole MCCB footprint that fits most DIN-rail or panel-mount enclosures without surprises. Operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C, so it handles cold warehouses and hot panel interiors.