What this MCCB brings to the panel
The Siemens SENTRON 3VA1020-3ED36-0DA0 is a 3-pole molded case circuit breaker rated for a continuous current of 20 A, with a TM210 thermal-magnetic release that handles both overload and short-circuit protection. The interrupting capacity hits 75.6 kA at 240 V, 52.5 kA at 415 V, and 32 kA at 440 V — numbers that give you real headroom for high-fault service entrances or industrial distribution panels where the available fault current is no joke. It's built as a line-protection device, so the trip curve and release are tuned for feeder and main breaker duty, not motor starting. This breaker includes an undervoltage release (UVR) as part of the auxiliary trip assembly, order code 3VA9608-0BB25. That UVR lets you drop the breaker remotely on loss of control voltage — useful in safety circuits or emergency-stop chains where you want the main feed to drop if the control supply fails. No auxiliary contacts are fitted from the factory, so if you need status feedback to a PLC or indicator lamp, you'll add those separately. The front face carries an IP40 rating, which means it's protected against tools and wires larger than 1 mm but not sealed against dust ingress — fine inside a clean enclosure, not for washdown areas.
Thermal derating — the real-world current you can actually run
The 20 A rating holds flat from 40 °C up to 50 °C. At 55 °C it derates to 19.2 A, at 60 °C to 18.8 A, at 65 °C to 18.4 A, and at 70 °C to 18 A. That's a gentle slope — you lose only about 10% at the top of the operating range. The rated insulation voltage is 800 V, and the operating temperature span runs from -25 °C to 70 °C, with storage from -40 °C to 80 °C. So if this breaker lives in a hot panel next to a drive or transformer, you still have usable headroom without oversizing the frame.
Panel fit and mounting
The breaker measures 130 mm high, 76.2 mm wide, and 70 mm deep. That 76.2 mm width is the standard three-pole MCCB footprint, so it drops into existing panel cutouts and busbar arrangements without surprises. It mounts via screw terminals and accepts the usual lug or busbar connections for the line and load sides. The IP40 front face means it's fine behind a closed panel door; no special gasketing needed for dry indoor locations.