63 A MCCB with 121 kA SCCR — what the ratings mean for your panel
The Siemens 3VA1163-4EF36-0CH0 is a SENTRON molded case circuit breaker (MCCB) rated 63 A continuous at 40 °C, with a short-circuit breaking capacity of 121 kA at 240 V AC. That 121 kA figure is the interrupting rating — it tells you this breaker can safely clear a fault current up to that level without welding contacts or rupturing the case, which is critical for high-fault panels near large transformers or utility feeds. The 63 A rating holds steady from 40 °C up to 50 °C (still 63 A), then derates to 62 A at 55 °C, 61 A at 60 °C, 60 A at 65 °C, and 58 A at 70 °C — so if your enclosure runs hot, you lose only about 8% at the top end. The 3-pole design and line-protection tuning (thermal-magnetic trip curve for cable and busbar protection) make this a straight fit for main or feeder duty in a distribution panel. Breaking capacity drops with voltage: 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That 11.9 kA at 690 V is the limiting factor — if your system runs 690 V line-to-line, verify your available fault current is below that. The rated insulation voltage is 800 V, so the internal clearances and creepage are sized for 690 V systems.
Built-in undervoltage release and auxiliary switch complement
This variant ships with an undervoltage release (UVR) integrated — the design of the auxiliary release is listed as undervoltage release. That means if the control voltage drops below the dropout threshold, the breaker trips immediately, which is standard for safety circuits or emergency-stop chains where loss of control power must open the main disconnect. It also carries 2 auxiliary switches plus 1 trip alarm switch (HQ), giving you status feedback for remote monitoring or PLC inputs. A trip indicator is present on the front face, so a walk-by inspection catches a tripped state without opening the panel door.
Physical fit — 76.2 mm wide, 130 mm tall, 70 mm deep
The 3VA1163-4EF36-0CH0 measures 76.2 mm wide (3 in), 130 mm tall (5.12 in), and 70 mm deep (2.76 in). That 76.2 mm width is a standard 3-pole MCCB footprint — it fits the same mounting cutout and busbar spacing as other SENTRON 3VA1 frame breakers. If you are swapping from a different brand or an older Siemens frame, check the mounting hole pattern and busbar center-to-center distance; the 70 mm depth is shallow enough for most 200 mm deep enclosures without crowding the gland plate.
Environmental and thermal limits
Operating temperature range is -25 °C to 70 °C, storage range is -40 °C to 80 °C. Maximum power loss at rated current is 19.8 W — that is the heat the breaker dumps into the enclosure, so factor it into your thermal budget if the panel is densely packed. No communication function and no ground-fault monitoring on this variant; it is a plain line-protection MCCB with UVR.