What this breaker is and what it carries
The Siemens 3VA1120-4EF36-0CC0 is a 3VA1 IEC frame 160 molded-case circuit breaker with a 36 kA breaking capacity at 415 V AC — class S, meaning it sits in the middle of the 3VA1 breaking-capability tiers, suited for distribution panels where fault levels are moderate but not trivial. It is a 3-pole unit with a TM240 thermal-magnetic trip unit, rated In = 20 A, with overload protection adjustable from 14 A to 20 A and short-circuit protection set at 8 to 16 times In. It ships with clamp terminals, an undervoltage release (UVR) for 120-127 V AC 50/60 Hz, and two auxiliary switches (HQ).
What the ratings mean for fit
The 36 kA Icu at 415 V AC is the ultimate short-circuit breaking capacity — the maximum fault current the breaker can safely interrupt once. That rating governs whether this breaker coordinates with upstream protective devices in a selective scheme; if the available fault current at the panel exceeds 36 kA, you need a higher class (E or H) in the same frame. The TM240 trip unit provides thermal (overload) and magnetic (short-circuit) protection: the thermal element tracks heating from sustained overcurrents, adjustable via the Ir dial between 14 A and 20 A, while the magnetic element reacts instantaneously to currents between 8× and 16× In (160 A to 320 A). The UVR drops the breaker when control voltage falls below the dropout threshold — common on safety circuits or emergency-stop chains where loss of control power must open the main disconnect.
Integration and deployment context
This breaker mounts on a DIN rail or can be screw-fixed into a panel enclosure. The clamp terminals accept copper or aluminium conductors without lug crimping — speeds up panel wiring on distribution boards. The two auxiliary switches (HQ) provide status feedback to a PLC or indication lamp; the UVR coil draws from a separate 120-127 V AC control circuit, so verify that supply is present before expecting the breaker to close. In a typical IEC distribution board, this unit feeds downstream branch circuits or a motor control centre, with the 36 kA rating giving headroom for most commercial and light industrial installations.