Motor protection MCCB with ETU350M — 40 A, 3-pole
The Siemens 3VA2140-7MN32-0BH0 is a SENTRON molded case circuit breaker (MCCB) in the motor protection version, rated for 40 A continuous current (Iu) across the full 40 °C to 70 °C ambient range — no derating needed up to that ceiling. Three poles, fitted with the ETU350M electronic overcurrent release, which gives you adjustable time-current curves for coordinating with motor start profiles. Breaking capacity hits 330 kA at 240 V, 242 kA at 415 V, and still 187 kA at 500 V — that's enough for high-fault utility feeds or transformer secondaries where standard MCCBs would cascade. At 690 V it drops to 3.8 kA, so keep it on the 400 V class bus for the interrupting rating you're paying for. Phase failure detection is built into the release, so a lost phase on the motor feeder will trip the breaker rather than let the motor single-phase and burn. That's the difference between a plain feeder breaker and a motor-protection MCCB — the release watches for unbalance, not just overload.
Sizing for motor duty — AC-3 power ratings
Rated operating power in AC-3 duty (squirrel-cage motor starting, switching during running) is 11 kW at 230 V and 18.5 kW at 400 V. That maps to a standard 18.5 kW / 25 hp motor on a 400 V three-phase supply — the MCCB is sized for the motor FLA plus starting inrush, not the bus rating.
Panel fit — dimensions and IP rating
Dimensions: 105 mm wide, 181 mm high, 86 mm deep. That's a 4.1-inch wide footprint — three of these sit in roughly 315 mm of DIN-rail or panel-mount width. IP40 on the front face means it's protected against tools and wires >1 mm, but not sealed against washdown; mount inside a cabinet, not in a wet zone.
Environmental and electrical ratings
Operating temperature range -25 °C to +70 °C; storage from -40 °C to +80 °C. Rated insulation voltage Ui 800 V, so it's suitable for 690 V systems (though the interrupting rating at that voltage is limited). Maximum power loss 10 W at rated current — negligible for panel heat budget.