What this MCCB carries
The Siemens 3VA1020-4ED32-0BC0 is a 3-pole SENTRON molded case circuit breaker (MCCB) rated 20 A continuously at 40 °C ambient, with a thermal derating curve that holds 20 A up to 55 °C and drops to 19 A at 70 °C. That flat plateau from 40 to 55 °C is useful in a warm panel — you're not losing headroom until the enclosure is genuinely hot. Breaking capacity runs 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. Rated insulation voltage is 800 V. That 121 kA at 240 V means this breaker can sit on a high-fault panel feeding a step-down transformer secondary without needing a current-limiting upstream device — it interrupts a bolted fault at that level on its own. Power loss is 14.5 W maximum — relevant for thermal budget in a sealed enclosure with other devices. Operating temperature range is -25 to 70 °C; storage from -40 to 80 °C. The 70 mm depth, 76.2 mm width, and 130 mm height fit the standard SENTRON 3VA mounting footprint, so it swaps into an existing panel layout without re-drilling the backplate.
Undervoltage release and auxiliary switches
This variant ships with an undervoltage release (UVR) and two HQ auxiliary switches built in. The UVR trips the breaker when control voltage drops below a threshold — common on safety circuits that need to drop a feeder on loss of control power. The two auxiliary switches give status feedback (open/closed) back to a PLC or annunciator panel. No communication function on this order code; it's a standalone line-protection device. The basic switch supplied is 3VA10204ED320AA0. Trip indicator is not fitted — you'd rely on the auxiliary switch state or the handle position to confirm tripped status.
Panel fit against a higher-current sibling
A buyer comparing this 20 A breaker (3VA1020-4ED32-0BC0) against the 100 A 3VA1110-5ED36-0AC0 should know the physical footprint differs — the 100 A frame is larger in all dimensions. The 20 A unit drops into a panel cutout sized for the 3VA10 frame; the 100 A unit needs the 3VA11 frame spacing. No rewiring is possible without reworking the bus bars and enclosure layout. For a 20 A feeder branch, this is the correct frame.