What this MCCB is and where it fits
The Siemens 3VA1120-6EF36-0JH0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection in distribution panels. Its 20 A continuous rating and 3-pole construction suit it for feeder or branch-circuit duty in commercial and light industrial switchboards. Breaking capacity reaches 220 kA at 240 V AC, 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 690 V — figures that cover most low-voltage fault scenarios without needing a current-limiting upstream device. The thermal-magnetic trip unit (TM240) provides fixed thermal and magnetic protection, no electronic adjustments or communication module. This is a straightforward, non-communicating breaker for hardwired panels where remote monitoring isn't required.
Thermal derating and panel integration
Rated continuous current holds at 20 A from 40 °C through 50 °C ambient. Above that the curve steps down: 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. If the panel runs hot — near a transformer or drive bank — size the load to the 70 °C figure, not the nameplate. Footprint is 76.2 mm wide, 130 mm tall, 70 mm deep — a standard 3-pole MCCB envelope that drops into most DIN-rail or panel-mount SENTRON bases without re-drilling. IP40 on the front face keeps dust out of the enclosure; the back and sides rely on the panel's own IP rating. Mechanical endurance is rated at 15 000 operations — typical for a fixed-trip MCCB in a distribution role where it's not cycled daily. The auxiliary contact block (2 auxiliary switches + 1 trip alarm switch HQ) is integrated, so you get status feedback without an add-on module.
Accessory and release options
This variant includes a shunt trip (STL) release for remote tripping — useful in emergency-stop or fire-safety circuits. The integrated auxiliary trip is order code 3VA9688-0BL32. No undervoltage release or ground-fault monitoring is fitted on this version. A voltage trigger is present, and the trip indicator gives local visual confirmation of a fault event. Phase failure detection and communication functions are absent — this is a pure protection device, not a metering breaker.