MCCB for line protection — 20 A, 187 kA IC, UVR included
The Siemens 3VA1120-5EF32-0BH0 is a SENTRON molded case circuit breaker (MCCB) rated 20 A continuous at 40 °C, with a 3-pole construction and a maximum breaking capacity of 187 kA at 240 V AC. It carries an integrated undervoltage release (UVR) and comes factory-fitted with two auxiliary switches plus one trip alarm switch HQ. This is a line-protection design — no communication function or ground-fault monitoring — intended for straightforward feeder or branch-circuit duty in distribution panels.
Breaking capacity and thermal derating
The interrupting rating drops with system voltage: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. That makes it a high-interrupting option for 240 V and 415 V panels where fault current is stiff. Thermal derating is minimal up to 55 °C (full 20 A), then steps to 19 A at 60 °C through 70 °C. The rated insulation voltage is 800 V, so it can sit on a 690 V bus without an extra insulation barrier.
Panel fit and auxiliary wiring
Width is 76.2 mm (3 in), depth 70 mm, height 130 mm — a standard 3-pole MCCB footprint that drops into a DIN-rail or panel-mount assembly without surprises. The auxiliary switch block (2 aux + 1 trip alarm HQ) is pre-installed, so you don't need to order a separate accessory or open the cover to add it. Power loss at full load is 14.5 W — factor that into enclosure thermal calculations if the panel is densely packed.