125 A MCCB with shunt trip — panel fit and breaking capacity
The Siemens 3VA1112-3EF36-0KA0 is a SENTRON 3-pole molded case circuit breaker rated 125 A continuous at 40 °C (derates to 114 A at 70 °C ambient). Its interrupting capacity reaches 75.6 kA at 240 V AC, 52.5 kA at 415 V, and 11.9 kA at 690 V — covering most low-voltage distribution and motor branch circuits in industrial panels. The 70 mm depth and 76.2 mm width fit standard MCCB mounting footprints on DIN rails or panel backplates. This unit includes a factory-installed shunt trip (STL) auxiliary release for remote tripping via a control signal — useful in emergency-stop chains or automated shutdown sequences. The TM240 thermal-magnetic overcurrent release provides fixed thermal and magnetic trip settings for line protection, with no ground-fault monitoring or communication module built in.
Breaking capacity by voltage — what the ratings mean for your fault-current study
At 240 V the breaker clears 75.6 kA symmetrical — enough for most service-entrance and sub-feed applications. At 415 V that drops to 52.5 kA, and at 690 V to 11.9 kA. The 800 V rated insulation voltage (Ui) confirms the insulation system is designed for 690 V line-to-line circuits. Match the available fault current at your point of common coupling against these values; the 415 V figure is the one most panel builders check for 400 V-class distribution.
Thermal derating — real-world current capacity in a warm panel
Rated 125 A up to 50 °C without derating. Above that it drops: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, 114 A at 70 °C. Operating ambient range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. Maximum power loss is 28.1 W — factor that into enclosure heat calculations if the panel is densely packed.