What this MCCB carries and where it fits
The Siemens 3VA1120-3EF32-0DA0 is a SENTRON 3VA1 molded case circuit breaker rated for 20 A continuous current (Iu) with a TM240 thermal-magnetic release — a fixed-trip unit sized for line protection in distribution panels and motor branch circuits. The 3-pole design breaks up to 75.6 kA at 240 V and still clears 52.5 kA at 415 V, so it handles high available fault current on the secondary side of a typical 480 V–208Y/120 V transformer without needing a current-limiting fuse upstream. The TM240 release is a thermal-magnetic fixed-trip — no interchangeable rating plugs, no dial adjustment. That means the 20 A frame is locked; if the load draw changes, the breaker itself gets swapped, not just the trip unit. The thermal curve tracks the 20 A rating across ambient from 40 °C to 70 °C, derating from 20 A at 50 °C down to 18 A at 70 °C, which matters when the breaker lives in a crowded, warm enclosure. An undervoltage release (UVR) is built in — part of the auxiliary release design — so the breaker can be tripped remotely on loss of control voltage, a common requirement for emergency-stop circuits or undervoltage protection on machine feeders. The UVR is wired separately from the main power path; the release coil draws from a control supply, not the load side.
Breaking capacity across voltage levels
This MCCB's interrupting rating varies sharply with system voltage, which is typical for a thermal-magnetic breaker: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 10.5 kA at 690 V. On a 480 V wye system (phase-to-ground 277 V, phase-to-phase 480 V), the relevant rating is the 415 V or 440 V figure — the breaker is rated for the line-to-line voltage of the circuit it protects. For a 480 V delta corner-grounded system, the 440 V rating applies. The 690 V figure covers 600 V class Canadian and some IEC industrial networks.
Panel fit and mounting
The 3VA1 frame measures 76.2 mm wide, 130 mm tall, and 70 mm deep — a compact footprint that fits standard 3-pole MCCB spacing on a DIN rail or panel-mount base. The IP40 front protection means the breaker face is protected against tools and solid objects over 1 mm, but the enclosure itself must provide the overall panel IP rating. No auxiliary contacts are factory-installed (auxiliary contact version: without), so if you need status feedback to a PLC or a remote trip indication, order the separate 3VA9608-0BB25 auxiliary trip block.