What this MCCB is and what it does
The Siemens SENTRON 3VA1020-4ED36-0KC0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection — meaning it sits at the feeder or branch level to protect cables and busbars from overloads and short circuits, not motor or device protection. Rated 20 A continuously at 40 °C (derates to 19 A at 60 °C and above), it carries a rated insulation voltage of 800 V and can interrupt up to 121 kA at 240 V AC, stepping down to 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 500 V or 690 V. That interrupting capacity profile tells you this breaker is built for high-fault panels — think main or large feeder duty where available fault current is substantial.
What the ratings mean for fit
The 20 A rating at 40 °C is the continuous current the breaker can carry without tripping in a 40 °C ambient — standard for most enclosed panels. If your panel runs hotter, the derating curve is explicit: 19 A from 60 °C to 70 °C. That matters when you're coordinating with upstream protection or sizing for a known load. The interrupting capacity (Icu) at each voltage level tells you the maximum fault current the breaker can safely clear at that voltage — 121 kA at 240 V is very high, suitable for transformer-secondaries or large busway feeds. At 690 V it drops to 11.9 kA, still adequate for most 690 V distribution but not for ultra-high-fault industrial grids. The 3-pole configuration and line-protection design mean it trips on phase faults and overloads but has no built-in ground-fault monitoring.
Panel integration and accessories
This MCCB ships with a shunt trip (STL) release and two HQ auxiliary switches pre-installed — the shunt trip lets you remotely trip the breaker via a control voltage, useful for emergency-stop circuits or interlocking with fire-alarm systems. The auxiliary switches provide status feedback (open/closed) to a PLC or indicator lamp. Dimensions are 76.2 mm wide, 130 mm high, 70 mm deep — a standard SENTRON 3VA footprint that fits existing panel cutouts and busbar systems for the series. No communication function on this variant; it's a standalone thermal-magnetic breaker, not a communicable power-management unit. Power loss is 12 W maximum at rated current — negligible for thermal budgeting in most enclosures.