What this MCCB is and what it does
The Siemens SENTRON 3VA1020-3ED36-0BC0 is a 3-pole molded case circuit breaker (MCCB) rated for 20 A continuous current, built for line protection in distribution panels. Its TM210 thermal-magnetic release handles overloads and short circuits without needing an external trip unit — so it's a self-contained protector for branch circuits feeding motor control centers, lighting panels, or general power distribution. The interrupting ratings climb to 75.6 kA at 240 V and 52.5 kA at 415 V, which gives you headroom for high-fault installations like transformer secondaries or large busway feeds.
Key ratings and what they mean for your panel
The 20 A rating holds steady from 40 °C up to 50 °C — no derating needed in a typical warm panel. At 55 °C it drops to 19.2 A, and at 70 °C it's 18 A. That thermal curve matters if you're packing breakers tight in a non-ventilated enclosure; you can still count on 18 A at the upper ambient limit. The 800 V rated insulation voltage (Ui) tells you the internal creepage distances are designed for 690 V line-to-line systems, so it's safe on 400/480 V supplies with margin. The interrupting ratings are given at four voltages: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at 690 V. For a 480 V panel you'd use the 440 V figure (32 kA) as the closest conservative guide — that's enough to clear a fault downstream of a large transformer without the breaker welding shut. The TM210 release is fixed, so you set the thermal pickup via the dial and the magnetic trip is factory-calibrated; no separate trip unit to order.
Built-in undervoltage release and auxiliary contacts
This breaker ships with an undervoltage release (UVR) already installed — part number 3VA9608-0BB11 for the release itself. The UVR trips the breaker when supply voltage drops below a threshold, which is standard for safety circuits that need to drop a motor feeder on loss of control power. It also carries 2 auxiliary switches (HQ type) for remote status indication — you can wire those to a PLC input to know whether the breaker is open or closed without walking the panel. The front face is rated IP40, so it's protected against tools and wires larger than 1 mm — fine for a clean indoor panel. No trip indicator on the front, so you'll rely on the auxiliary contacts or a visual check of the handle position. Latching endurance is rated at 15,000 operations, which is typical for a distribution breaker that sees infrequent switching.