What this MCCB is and what it does
The Siemens 3VA1020-3ED36-0AE0 is a SENTRON molded case circuit breaker (MCCB) with three poles, rated 20 A continuous at 40 °C and carrying a TM210 thermal-magnetic release — fixed thermal, fixed magnetic, no adjustment dial. It is a line-protection design (not motor-protection), meaning the magnetic trip is set higher than a typical motor-protection curve to ride through transformer inrush and feeder-start transients. Rated insulation voltage is 800 V, so it is suitable for 480/277 V and 600 V class systems with margin. The interrupting ratings climb as voltage drops: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at 500 V and 690 V. That 75.6 kA at 240 V is the figure to check if you are feeding a panel from a large transformer — it beats many compact MCCBs in that voltage class.
Thermal derating and ambient temperature
The 20 A rating holds from 40 °C up to 55 °C without derating. At 60 °C and 65 °C it drops to 19 A; at 70 °C it stays at 19 A. That means in a warm enclosure — say a non-ventilated panel next to a drive — you still get 19 A continuous. The maximum operating temperature is 70 °C, storage range -40 °C to 80 °C.
Mounting and dimensions
Width 76.2 mm (3 in), height 130 mm (5.12 in), depth 70 mm (2.76 in). Three-pole footprint is standard for a 20 A frame; it mounts directly on a DIN rail or panel. The auxiliary switch slot accepts up to four HQ auxiliary switches — no undervoltage release or shunt trip on this variant, so if you need UVR or communication, you are looking at a different 3VA order code.