Line protection with ETU850 — what the ratings mean for fit
The Siemens 3VA2010-5KP32-0DH0 is a 3-pole SENTRON molded case circuit breaker (MCCB) rated for line protection with a continuous current Iu of 100 A and a rated insulation voltage Ui of 800 V. The ETU850 electronic trip unit provides adjustable overload and short-circuit protection curves, making it suitable for feeder or main breaker duty in distribution panels. The 187 kA breaking capacity at 240 V AC means it can safely interrupt very high fault currents without upstream fuses — a key spec for high-fault installations like transformer secondaries or large motor control centers.
Breaking capacity across voltages — the so-what
Breaking capacity drops with voltage: 187 kA at 240 V, 121 kA at 415 V and 440 V, 79 kA at 500 V, and 3.4 kA at 690 V. The 121 kA at 415 V is the figure most relevant for European 400 V three-phase panels — it exceeds typical utility fault levels, so the breaker can be applied without series fusing in most commercial and light industrial installations.
Thermal derating and ambient limits
Rated 100 A up to 50 °C ambient; above that it derates linearly to 85 A at 70 °C. Operating range is -25 °C to +70 °C, storage -40 °C to +80 °C. The 16 W maximum power loss matters for panel heat budget — in a sealed enclosure with multiple breakers, that adds up.
Integrated auxiliary and undervoltage release
Comes with 2 auxiliary switches plus 1 trip alarm switch (HQ type) and an undervoltage release (UVR). The UVR trips the breaker when control voltage drops — standard for safety circuits that need to drop out on loss of control power. Communication function is also present, allowing integration into higher-level monitoring systems.