The Siemens SENTRON 3VA1112-5EF36-0AF0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying 125 A continuously at 40 °C without derating. Its TM240 thermal-magnetic release handles overload and short-circuit protection in a single unit — the thermal element tracks RMS heating, the magnetic element clears fast on high fault currents. Breaking capacity reaches 187 kA at 240 V, 121 kA at 415 V, and 75.6 kA at 440 V, which covers most industrial secondary-distribution fault levels without cascading upstream.
Thermal derating and continuous current
The 125 A rating holds flat from 40 °C up to 50 °C, then gradually declines: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. If the panel ambient runs above 50 °C, the 3VA1112-5EF36-0AF0 still delivers over 90 % of its nominal rating — useful for sealed enclosures or high-density switchboards where heat buildup is a given. Maximum power loss at rated current is 28.1 W, which factors into enclosure thermal calculations.
Breaking capacity across voltage levels
This MCCB's interrupting rating varies significantly with system voltage. At 240 V it clears 187 kA — enough for high-fault panels near large transformers. At 415 V the rating is 121 kA, at 440 V it is 75.6 kA, and at 500 V or 690 V it drops to 17 kA. The 800 V rated insulation voltage (Ui) confirms the breaker is physically designed for 690 V systems, but the 17 kA limit at that voltage means the available fault current must be verified before specifying it on a 690 V bus.
Physical fit and auxiliary switching
Dimensions are 130 mm high, 76.2 mm wide, and 70 mm deep — a standard 3-pole MCCB footprint that fits Siemens SENTRON mounting bases and panel cutouts. The breaker ships with one auxiliary switch and one trip alarm switch (HQ design), so it reports both the closed/open state and whether it tripped on fault. No undervoltage release, no ground-fault module, and no communication function are included on this variant — those are separate add-on accessories.