What it is and what it does
The Siemens 3VA1020-4ED36-0BC0 is a 3-pole IEC circuit breaker on the 3VA1 frame, rated at In=20A with a TM210 thermal-magnetic trip unit providing fixed overload protection at Ir=20A and fixed short-circuit protection at Ii=16 x In. Its breaking capacity class S delivers Icu=36kA at 415V AC, which means it can safely interrupt a fault current up to that level without upstream cascading — a key spec for panel coordination studies.
Integration and deployment
The 3VA1 frame mounts on DIN rail or panel-mount in standard distribution and motor-control-centre enclosures. The clamp connection accepts copper or aluminium conductors up to the frame's rated cross-section. The integrated undervoltage release (UVR) at 24V DC trips the breaker on loss of control voltage — common in emergency-stop chains or safety circuits where a sustained undervoltage must open the load. Two auxiliary switches (HQ) provide status feedback to a PLC or indication panel.