Transformer-protection circuit breaker, size S00
The Siemens 3RV2811-0ED10 is a SIRIUS circuit breaker in size S00, designed specifically for transformer protection and listed to UL 489 / CSA C22.2 No.5. That UL 489 listing means it qualifies as a branch-circuit protective device in North American panels — not just a motor-protective breaker — so it can serve as the primary overcurrent protection for a control transformer secondary. Rated breaking capacity is 100 kA at 240 V, 400 V, 500 V, and 690 V AC — a flat 100 kA across the common industrial voltages. That eliminates the need to check a derating curve when the supply voltage changes within a panel; the SCCR stays at 100 kA regardless of whether the line is 400 V or 690 V.
Width is 45 mm, depth 97 mm, height 144 mm. Clearance requirements: 70 mm above and below, 30 mm to the sides, 0 mm forward and backward. The zero forward/backward clearance means the breaker can be butted directly against the back panel or enclosure door without derating — useful when gland-plate depth is tight.
Termination and environment
Main contacts use M4 screw-type terminals, accepting 1 to 10 mm² solid or stranded, up to 2 × 10 mm². Screwdriver shaft diameter 5 to 6 mm, Pozidriv size 2 tip — standard panel-building tooling. The wide storage range covers unheated warehouses and container shipping without special handling.