What this MCCB is and where it fits
The Siemens 3VA1120-6EF36-0CH0 is a SENTRON molded case circuit breaker (MCCB) configured for line protection — meaning it guards feeder and branch circuits against overload and short-circuit, not motor or generator duty. It is a 3-pole unit rated for a continuous current Iu of 20 A, with a TM240 thermal-magnetic release that provides fixed thermal and magnetic trip characteristics per the 240 frame designation. The breaker carries a rated insulation voltage Ui of 800 V, which sets the dielectric withstand level for the internal construction. The interrupting capacity is specified at four voltage points: 220 kA at 240 V, 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 690 V. These figures define the maximum prospective fault current the breaker can safely clear at each voltage level — critical for selectivity studies and SCCR compliance in distribution panels. The 220 kA at 240 V is a high-endurance rating typical for large transformer secondaries or utility tie points. Thermal derating is documented across the operating range: the breaker holds 20 A continuously from 40 °C through 50 °C, then steps down to 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. This curve matters when the breaker is enclosed in a warm panel or mounted adjacent to other heat sources — the 70 °C rating is the one to use for worst-case ambient calculations. The operating temperature range spans -25 °C to 70 °C, with storage extremes of -40 °C to 80 °C.
Auxiliary and undervoltage release configuration
This breaker ships with an integrated undervoltage release (UVR) — design code 6EF36 indicates the UVR is factory-installed. The UVR trips the breaker when control voltage drops below a set threshold, which is standard for safety circuits that need to guarantee a de-energized state on loss of control power. The auxiliary contact block provides 2 auxiliary switches plus 1 trip alarm switch (HQ configuration), giving status feedback for remote monitoring or PLC inputs. The trip alarm switch changes state only on a fault trip, not on manual switching, which is useful for distinguishing between intentional isolation and protective interruption. The auxiliary release order code for replacement or spare parts is 3VA9608-0BB24. The breaker carries an IP40 protection class on the front face, meaning it is protected against tools and small wires entering from the front but is not sealed against water ingress — standard for enclosed panel mounting. Physical dimensions are 130 mm height, 76.2 mm width, and 70 mm depth, which fits the standard SENTRON 3VA mounting footprint for 3-pole frames.
Lifecycle and sourcing posture
For procurement: this part is sourced and quoted to order against an RFQ through independent distribution channels. Availability and current pricing are confirmed at quote time. The part carries no communication function, no phase failure detection, and no ground fault monitoring — it is a straightforward thermal-magnetic line protection breaker with undervoltage release, suited for fixed-trip applications where adjustable electronic trip units are not required.