Breaking capacity that stays with you
The 3VA1112-6EF36-0DC0: This 3VA SENTRON MCCB carries a 220 kA interrupting rating at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, and still holds 17 kA at 690 V. That's not a lab number — it means this breaker can sit downstream of a big transformer or a utility feed and still clear a bolted fault without welding its contacts shut. For a panel builder, that's the difference between a coordinated selective system and a cascade failure that takes out the main breaker too. The TM240 thermal-magnetic release is fixed-trip, so you're not fiddling with adjustment knobs. What you set at the factory is what it opens at. Rated continuous current Iu is 125 A, and the insulation voltage Ui is rated 800 V — that's the voltage the guts are designed to withstand without tracking or flashover.
Thermal derating — the real-world curve
This MCCB holds a full 125 A from 40 °C through 50 °C. At 55 °C it drops to 120 A, then 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. If your panel sits next to a hot motor drive or a solar combiner box, that's the number you need for the BOM — not the catalog nominal. Out here in the grease, I've buried plenty of breakers that looked good on paper but tripped early because nobody checked the ambient column.
Built for a panel, not a lab bench
Three poles, 70 mm deep, 76.2 mm wide, 130 mm tall. That 76.2 mm width is a standard 3-module DIN footprint — it clips onto the rail and stays put. The front face carries IP40 protection, so routine panel dust and accidental screwdriver pokes won't get inside. Undervoltage release is built in (part of the integrated auxiliary trip 3VA9608-0BB25), and it ships with two auxiliary switches HQ for status feedback to the PLC or alarm annunciator.