What it is and what it does
The Siemens 3VA2340-7HN32-0CC0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current, with a 3-pole configuration and an ETU350 electronic trip unit. It's a line-protection device built for main or feeder duty in distribution panels — the kind of breaker you spec when you need adjustable protection curves and high fault-current handling in a compact frame. The interrupting capacity tells you where this thing lives in the hierarchy: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 52.5 kA at 690 V. That's utility-grade fault clearing — it sits upstream of smaller feeder breakers and needs a panel SCCR rated to match.
Ratings that matter for panel fit
The 400 A continuous rating holds across 40 °C, 45 °C, and 50 °C ambient — no derating needed in a warm enclosure. At 55 °C it's 385 A, at 60 °C it's 370 A, at 65 °C it's 355 A, and at 70 °C it's 340 A. That derating curve is what you check if the breaker sits near transformers or drives. Operation range is -25 °C to 70 °C; storage from -40 °C to 80 °C. Rated insulation voltage is 800 V, so it's comfortable on 690 V systems. Maximum power loss is 98.5 W — that's heat you need to account for in the enclosure thermal calculation. Mechanical endurance is 15,000 operations latching. That's a standard figure for a fixed-mount MCCB in distribution — not a switching-duty contactor, but fine for its role as a protective device that operates infrequently.
Trip unit and auxiliary hardware
The ETU350 electronic trip unit is the brain — it gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves. This variant ships with an undervoltage release (UVR) installed, which drops the breaker when control voltage falls below a threshold — standard for safety circuits that need to guarantee a loss-of-power trip. It also carries 2 auxiliary switches (HQ type) for status feedback to a PLC or indication lamp. No voltage trigger, no phase-failure detection, no ground-fault monitoring, and no communication function on this variant. It's a straight-line protection breaker — add external modules if you need those features.
Physical fit and panel integration
Dimensions are 248 mm high, 138 mm wide, 110 mm deep. That's a standard SENTRON 3VA frame size — it mounts on a DIN rail or bolts directly into a panel bus. The 110 mm depth means it fits in shallow enclosures where a taller frame would force a deeper can.