What this MCCB is and what it protects
The Siemens SENTRON 3VA1120-4EF32-0CC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection in distribution panels. It carries a continuous current of 20 A at 40 °C, derating to 19 A at 65 °C, so it's sized for a 20 A feeder or branch circuit in a 400 V class switchboard. Its interrupting capacity is the headline spec: 121 kA at 240 VAC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 500 V and 690 V. That 121 kA at 240 V means it can clear a bolted fault on a high-capacity transformer secondary without upstream fuses — a common requirement in North American industrial panels where the available fault current is high. Rated insulation voltage is 800 V, so the breaker is suitable for 690 V line-to-line systems (common in mining, oil & gas, and European industrial networks) with adequate clearance margins.
Built-in undervoltage release and auxiliary switches
This variant ships with an undervoltage release (UVR) fitted — the entry confirms it. That UVR will trip the breaker if the control voltage drops below its dropout threshold, which is useful for emergency-stop circuits or to prevent automatic restart after a brownout. The UVR is wired separately from the main power path; verify the coil voltage rating on the nameplate before connecting. It also includes two factory-fitted auxiliary switches (HQ design) for remote status indication — one normally-open and one normally-closed contact, typically wired to a PLC input or a panel lamp to show the breaker's open/closed state. No communication module is fitted, so this is a standalone breaker with hardwired signals only.
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 fits most Siemens SENTRON distribution boards and third-party enclosures with busbar cutouts spaced at 25 mm per pole. The 70 mm depth is shallow enough for slim wall-mount enclosures; check the handle clearance for the door cutout. Maximum power dissipation is 14.5 W at rated load, so adjacent devices in a sealed enclosure need derating consideration — allow natural convection or a small vent if the panel is densely packed.
Lifecycle and sourcing reality
For a critical-spare holding, one in the cabinet is cheap insurance. If you're stocking for a legacy panel that already uses the 3VA1 family, this exact order code is the drop-in replacement — no rewiring or busbar rework needed.