What it is and what it does
The Siemens SENTRON 3VA1020-3ED36-0BH0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying 20 A continuously at 40 °C ambient and derating to 19 A at 60 °C. Its interrupting capacity hits 75.6 kA at 240 V AC, dropping to 52.5 kA at 415 V and 7.5 kA at 690 V — so it handles high-fault utility feeds downstream of a transformer but needs a check at higher line voltages. Rated insulation voltage is 800 V, which covers most 480/277 V and 600 V panels with margin. This is a line-protection design — meaning it's configured for cable and busbar protection, not motor or generator duty. The integrated undervoltage release (UVR) trips the breaker when control voltage drops below a threshold, which is common in emergency-stop chains or mains monitoring circuits. Two auxiliary switches plus a separate trip-alarm switch (HQ) are built in, so you get status feedback without adding external blocks.
Panel fit and mounting
Footprint is 76.2 mm wide by 130 mm tall by 70 mm deep — a standard 3-pole MCCB width that fits most DIN-rail or screw-mount panel layouts. The 70 mm depth means it clears a 100 mm deep enclosure with room for wiring gutters. No communication module on this variant, so no extra width for a comms plug.