Line protection with ETU350 — what the ratings mean for the panel
The Siemens 3VA2163-5HN32-0AD0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) sized for 63 A continuous duty (rated current Iu) and built around the ETU350 electronic trip unit. The 187 kA breaking capacity at 240 V means this breaker can safely interrupt a fault current up to that level without welding contacts or cascading failure upstream — critical for high-fault installations near large transformers or in industrial mains distribution. At 415 V and 440 V the rating holds at 121 kA; at 690 V it drops to 4.25 kA, so verify the available fault current at your service voltage. The 3-pole construction handles three-phase line protection, and the product version is explicitly line protection — not motor protection, so no overload class or phase-loss curve is built in.
Thermal derating and panel integration
The 63 A rating holds flat from 40 °C through 50 °C (–). At 55 °C it derates to 60.6 A, at 60 °C to 58.3 A, and at 70 °C to 53.6 A. If the breaker sits in a warm enclosure or next to other heat sources, use the 55 °C or 60 °C figure for your continuous load calculation — the 63 A nameplate applies only up to 50 °C ambient. Dimensions are 86 mm deep, 105 mm wide, and 181 mm tall. The front face carries an IP40 protection class, meaning it is protected against tools and wires >1 mm but not against water ingress — suitable for dry indoor panel mounting. The breaker ships with 3 auxiliary switches HQ for status feedback to a PLC or indication lamp. Power loss is 4 W maximum, negligible for enclosure heat budgeting.
Trip unit and auxiliary configuration
The ETU350 is an electronic trip unit with LI (long-time and instantaneous) protection, adjustable via rotary dials on the front face. It does not include ground-fault monitoring, undervoltage release, voltage trigger, phase-failure detection, or communication function. The auxiliary release design is without auxiliary release, meaning no shunt trip or UVR is factory-installed — those are separate add-on modules. The breaker has no trip indicator. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.