MCCB for line protection with undervoltage release
The Siemens SENTRON 3VA1112-3EF32-0DA0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection. Its TM240 overcurrent release provides thermal-magnetic protection, and the built-in undervoltage release (UVR) trips the breaker when supply voltage drops below a set threshold — critical for preventing motor re-acceleration after a dip or outage. Rated 125 A at 40 °C and carrying 75.6 kA breaking capacity at 240 V, this MCCB handles high fault currents typical of industrial main feeders or large sub-distribution boards.
Breaking capacity across voltage levels
Breaking capacity drops with system voltage: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at both 500 V and 690 V. The 11.9 kA figure at 690 V is the limiting value for this frame — verify it against the available fault current at the point of installation. Insulation voltage is rated 800 V, so the breaker is electrically suitable for 690 V systems.
Thermal derating and power loss
Current rating holds at 125 A up to 50 °C ambient, then derates linearly: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. Maximum power loss is 30.6 W — account for this in enclosure thermal calculations, especially in high-density panels. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Panel fit and dimensions
Mounts on a standard DIN rail or direct panel. Dimensions are 130 mm height, 76.2 mm width (3 inches), and 70 mm depth. The 3-pole width is standard for this current class — verify busbar or cable lug spacing against the existing panel layout. No communication function or ground-fault monitoring on this variant.