The Siemens 3RV2811-0DD10 is a SIRIUS circuit breaker in the S00 frame size, designed specifically for transformer protection per UL 489 and CSA C22.2 No. 5. That design designation means the thermal and magnetic trip curves are shaped to handle transformer inrush without nuisance tripping — a different profile from a standard motor-protective breaker.
Breaking capacity — what 100 kA means here
This breaker carries a 100 kA interrupting rating at 240 V, 400 V, 500 V, and 690 V AC. That is a flat 100 kA across the entire common industrial voltage range — you do not need to derate the fault-interrupt capability as line voltage rises. For a transformer primary circuit, that matters: a large transformer can feed a sustained fault current well above 50 kA, and this breaker clears it without cascading upstream. The rated operational voltage for AC-3 motor-switching duty is 690 V maximum, but the transformer-protection design is the primary role here.
Dimensions: 97 mm deep, 45 mm wide, 144 mm tall. That zero forward clearance is useful in a tight enclosure; the breaker can sit flush against the back panel or a gland plate. Screw terminals with M4 bolts; Pozidriv size 2 tip, shaft diameter 5 to 6 mm.
Environmental tolerance
That -20 °C floor is fine for most indoor industrial panels; if the enclosure sits in an unheated warehouse in a cold climate, verify the ambient stays above that during operation. No ground-fault or phase-failure detection built in — this is a straight thermal-magnetic breaker, not an electronic protection relay.