What this MCCB is and what it does
The Siemens SENTRON 3VA1120-3EF36-0JH0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection in distribution panels and industrial switchboards. It carries a rated current of 20 A with full thermal capacity maintained from 40 °C through 55 °C, derating to 19 A at 60 °C and above — relevant for panels running warm in non-climate-controlled enclosures. Breaking capacity is the headline selector here: 75.6 kA at 240 V AC, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That 75.6 kA figure at 240 V covers high-fault service-entrance applications on 208Y/120 V or 240 V delta systems; the 52.5 kA at 415 V handles most European 400 V distribution without upstream fusing. Rated insulation voltage is 800 V, so the breaker is rated for the full 690 V AC switching duty without internal creepage concerns.
Auxiliary and release configuration
Factory-fitted with a shunt trip release (STL) and two auxiliary switches plus one trip alarm switch (HQ configuration). The shunt trip allows remote tripping from a control system or emergency-stop circuit; the auxiliary switches provide status feedback to a PLC or indication lamp. No undervoltage release is fitted, and there is no ground-fault monitoring module on this variant. A voltage trigger and trip indicator are present on the breaker face — the trip indicator gives a visual flag that the breaker opened on a fault rather than manually, which speeds fault-finding on a line-down call.
Panel fit and mounting
Dimensions are 130 mm height, 76.2 mm width, 70 mm depth. The 76.2 mm width (3 in) is the standard 3-pole MCCB footprint for the SENTRON 3VA1 frame; it mounts on a DIN rail or directly to a mounting plate via the base slots. Maximum power loss is 12 W, so no special ventilation is required in a standard IP3X or IP4X enclosure. Storage range is -40 °C to 80 °C; operating ambient is -25 °C to 70 °C. The 70 mm depth is shallow enough to fit 200 mm deep enclosures with room for wiring behind the breaker.