63 A MCCB with undervoltage release — what the ratings mean for your panel
The Siemens 3VA1163-4EF36-0DA0 is a SENTRON molded case circuit breaker (MCCB) rated 63 A continuous at 40 °C ambient, 3-pole, designed for line protection in distribution panels. The TM240 thermal-magnetic release handles overload and short-circuit trip curves — the 240 frame size means the trip unit is matched to this 63 A rating, not a higher-tap adjustable unit. Breaking capacity is 121 kA at 240 V AC, 75.6 kA at 415 V, and 52.5 kA at 440 V, which gives solid headroom for high-fault commercial or light industrial service where the available fault current is known to be substantial. The rated insulation voltage is 800 V, so the breaker is suitable for 480/277 V and 600 V systems with proper coordination. This variant includes an undervoltage release (UVR) — the auxiliary release is specifically an undervoltage release type — which means the breaker will trip if the control voltage drops below a set threshold. That is a common requirement for safety circuits where a loss of control power must open the main breaker to prevent automatic restart. The UVR is factory-fitted; no field kit to install.
Thermal derating and power loss — panel integration notes
The 63 A rating holds flat from 40 °C through 50 °C ambient. Above that, derating is gradual: 62 A at 55 °C, 61 A at 60 °C, 60 A at 65 °C, and 58 A at 70 °C. So in a warm enclosure — say a non-ventilated panel near a process line — you still get 60 A at 65 °C, which is a 4.8% drop from the nameplate. Maximum power loss is 19.8 W, which is low enough that side-by-side mounting in a standard distribution panel is fine as long as natural convection is not blocked. Dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a 3-pole footprint that fits standard Siemens 3VA panelboard and enclosure cutouts. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.