What the breaking capacity numbers mean for your panel
The Siemens 3VA1125-6EF32-0DC0 is a 3-pole SENTRON molded case circuit breaker rated for 25 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. Its headline feature is the interrupting capacity: 220 kA at 240 V, 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 690 V. That 220 kA at 240 V means this breaker can safely clear a fault current up to 220,000 amps without welding its contacts or rupturing the case — critical for high-fault locations like transformer secondaries or large motor control centers where available fault current can exceed 100 kA. The 17 kA at 690 V tells you it's still usable on 690 V systems, but the fault-current ceiling drops sharply; don't spec it for a 690 V bus with more than 17 kA available.
Thermal derating — don't cook it
This breaker holds its full 25 A rating from 40 °C through 50 °C ambient. Above that, it derates: 24 A at 55 °C, 23.5 A at 60 °C, 23 A at 65 °C, and 22.5 A at 70 °C. If your panel runs hot — say a sealed enclosure in a Gulf Coast plant — you lose about 10 % of capacity by 70 °C. Plan your load accordingly; don't crowd the breaker next to a heat source inside the cabinet. The rated insulation voltage is 800 V, and the front face carries IP40 protection, so it's fine in a typical industrial panel but not for washdown environments.
Built-in undervoltage release and auxiliary contacts
This variant ships with an undervoltage release (UVR) already installed — designated by the '0DC0' suffix — so it will trip if supply voltage drops below a set threshold. That's useful for preventing automatic restart after a brownout or for safety circuits that need to drop the load on loss of control power. It also carries two auxiliary switches (HQ type) for status feedback to a PLC or indication lamp. The integrated auxiliary trip is order code 3VA9608-0BB25 if you need a replacement. No ground-fault monitoring or communication module on this version; it's a straight line-protection breaker.
Panel fit — dimensions and mounting
Physical footprint: 76.2 mm wide, 130 mm tall, 70 mm deep. That's a standard 3-pole MCCB width — it drops into a panel cutout sized for a 3-pole SENTRON or 3VL breaker without re-drilling the mounting plate. The 70 mm depth means it clears a standard 200 mm deep enclosure with room for wiring gutters. No trip indicator or voltage trigger on this variant; you'll need the auxiliary switch feedback to know its state remotely.