What this breaker is and what the ratings mean
The Siemens 3VA1020-2ED36-0BC0 is a 3-pole IEC frame 100 molded-case circuit breaker with a 20 A thermal-magnetic trip unit (TM210). The Icu of 16 kA at 415 V AC is the ultimate short-circuit breaking capacity — the breaker can safely clear a fault up to that level once and still be functional afterward. For motor or distribution panels on a 400 V supply, that rating covers most industrial fault currents without needing an upstream current-limiting device.
Protection settings and auxiliary wiring
Overload protection is fixed at Ir = 20 A (non-adjustable). Short-circuit protection is set at Ii = 16 x In, or 320 A — a magnetic-only instantaneous pickup that clears hard faults fast. The built-in undervoltage release (UVR) trips the breaker when control voltage drops below 24 V DC, a common requirement for emergency-stop or safety circuits. Two HQ auxiliary switches report the main contact position to a PLC or status lamp.