Transformer-protection circuit breaker with 100 kA SCCR
The Siemens 3RV1411-1CA10 is a SIRIUS circuit breaker designed specifically for transformer protection, with a rated breaking capacity of 100 kA at 400 V AC — enough to handle high-fault-current transformer primaries without cascading upstream. Trip Class 10 means it clears overloads within 10 seconds at 7.2× Ie, matching the inrush profile of a typical transformer winding. Phase failure detection is built in, so a lost leg on the supply side trips the breaker rather than letting the transformer single-phase and overheat downstream loads.
Mounting and wiring
Mounts via screw fixing or snap-on onto 35 mm DIN rail per DIN EN 60715, in any position. The 45 mm wide × 75 mm deep × 90 mm high footprint leaves clearance: 20 mm upward, 20 mm downward, 9 mm at the side, 0 mm forward or backward. Main circuit screw terminals accept 2× (0.5…1.5 mm²) solid or stranded, or 2× (0.75…2.5 mm²) — M3 thread on the main contacts.
Backup fuse coordination
No backup fuse required at 240 V. At 400 V use a gL/gG 80 A fuse upstream; at 500 V and 690 V step down to gL/gG 25 A. The breaker's own breaking capacity drops from 100 kA at 240/400 V AC to 10 kA at 500 V AC and 2 kA at 690 V AC — so at higher voltages the backup fuse is what keeps the fault current within the breaker's capability.