What this MCCB is and why it holds the line
The Siemens SENTRON 3VA2163-7MS32-0CA0 is a 3-pole molded case circuit breaker (MCCB) in the starter protection product version, rated for a continuous current Iu of 63 A at 40 °C and carrying a rated insulation voltage Ui of 800 V. That 800 V insulation class means it is comfortable on 400 V and 480 V distribution systems with headroom to spare — provided the system fault current stays within the breaker's interrupting rating at the point of installation. Breaking capacity is the headline number that decides whether this breaker clears a fault or welds shut. At 240 V it interrupts 330 kA; at 415 V and 440 V, 242 kA; at 500 V, 187 kA; and at 690 V, 52.5 kA. Those figures are symmetrical RMS — the values a coordination study needs to confirm selectivity with upstream and downstream devices. If your panel's available fault current at the breaker line terminals exceeds the rating at your system voltage, you need a current-limiting upstream device or a higher-rated frame. The overcurrent release is an ETU310M electronic trip unit — that is a microprocessor-based, LSI (long-time, short-time, instantaneous) curve with adjustable pickups and time delays. It gives you the selectivity granularity a thermal-magnetic cannot: you can shape the short-time band to ride through motor inrush and still clear a bolted fault downstream. The breaker also ships with an undervoltage release (UVR) as the auxiliary release, part number 3VA9608-0BB24, which drops the breaker on loss of control voltage — standard practice for emergency-stop chains and undervoltage protection schemes.
Thermal derating — the real current limit in a warm cabinet
The 63 A rating holds flat from 40 °C to 50 °C ambient. At 55 °C it derates to 60.48 A; at 60 °C, 59.22 A; at 65 °C, 57.96 A; at 70 °C, 56.7 A. If your panel ambient runs above 50 °C — say, a non-ventilated enclosure near a furnace line or a solar combiner box — you must apply that derating to the continuous load, not the breaker nameplate. The maximum operating ambient is 70 °C; storage range is -40 °C to 80 °C. Power loss at full rated current is 75 W, which contributes to the enclosure's internal temperature rise and must be factored into the thermal budget.
Panel fit and mechanical endurance
The breaker measures 105 mm wide, 181 mm high, and 86 mm deep. That 105 mm width is three pole spaces on a standard DIN rail or panel-mount grid — no surprise for a 3-pole MCCB. The 86 mm depth is the projection from the mounting surface to the front of the breaker, which matters when you are fitting a gland plate or a dead-front cover. Mechanical endurance is rated at 20 000 operations — that is the latching endurance, meaning the mechanism is good for that many close-open cycles before wear affects the trip latch engagement. For a motor-starting application cycling several times a shift, that is a finite but serviceable life; for an infrequently operated feeder, it is effectively permanent.