What the ratings mean for fit
The Siemens 3VA1125-4EF32-0BC0 is a SENTRON molded case circuit breaker (MCCB) with a 25 A rated continuous current (Iu) and a TM240 thermal-magnetic overcurrent release. The TM240 release means the thermal element is fixed at 25 A — no field-adjustable thermal dial — so this is a straight 25 A breaker for line protection, not a frame you can up-rate later. The 121 kA breaking capacity at 240 V AC tells you it can interrupt fault currents up to that level without welding or rupturing, which matters when the available fault current at the panel is high — typical for transformer-fed industrial switchgear. At 415 V the capacity is still 75.6 kA, and at 690 V it drops to 11.9 kA, so the voltage you're clearing at governs the SCCR you can count on for coordination studies. The 3-pole construction and 800 V rated insulation voltage (Ui) suit it for 480Y/277 V and 600 V delta systems common in North American and European industrial panels. The undervoltage release (UVR) is integrated — that's the coil that trips the breaker when control voltage drops below a threshold, often used in emergency-stop chains or to prevent auto-restart after a power loss. Two auxiliary switches (HQ type) are built in for status feedback to a PLC or indicator lamp. Derating is minimal up to 50 °C — the breaker holds 25 A flat from 40 °C to 50 °C, then drops to 24 A at 55 °C and 22.5 A at 70 °C. If your panel ambient runs hot (say, inside a crowded enclosure near drives), you need to account for that 2.5 A loss at the top end. Operating range is -25 °C to 70 °C, storage from -40 °C to 80 °C.
Deployment context — panel integration
This MCCB is a panel-mount device, not DIN-rail snap-on. The 76.2 mm width (roughly 3 inches) and 130 mm height fit standard MCCB cutouts in industrial enclosures. Depth is 70 mm, which leaves clearance for rear-mounted bus bars or wiring ducts. The IP40 front protection means it's protected against tools and wires >1 mm — fine for a closed panel, but not for washdown or outdoor exposure without an additional enclosure. The auxiliary contact version is listed as 2 auxiliary switches HQ. HQ typically denotes high-rupturing-capacity contacts rated for switching control circuits directly without intermediate relays — useful for direct PLC inputs or contactor coils in the same panel.
Lifecycle and sourcing reality
Sourced and quoted to order through independent distribution. Availability and current pricing are confirmed at quote time against an RFQ. The part carries no communication function and no phase-failure detection.