What it is and where it sits
The ABB 1SAM101901R0001 is a front-mount auxiliary contact block carrying one normally-open and one normally-normally-closed contact in a 9 mm housing, rated 3 A at 400 V. It is sized as a signal/control side-car for ABB manual motor protectors and small contactors — the 3 A thermal current and 400 V insulation rating govern pilot duty, contactor coil feedback, and indicator lamp loads, not the motor power path itself.
Why 3 A / 400 V is the spec to size against
On auxiliary blocks the 3 A figure is the thermal current limit and 400 V is the rated insulation voltage for the control circuit — together they set the ceiling for indicator lamps, contactor coils and PLC input signaling, so the buyer should size the worst-case pilot load against 3 A rather than against the breaker's power rating. The 1NO+1NC arrangement gives one feedback path for closed state and one for open state, which lets the block mirror the upstream device's status to the control circuit.
Same-housing alternative if NO/NC is wrong for the BOM line
The closest functional alternative in the same 9 mm housing is ABB 1SAM101901R0002, which swaps the 1NO+1NC pair for a 2NO arrangement at the same 3 A and 400 V ratings — so a panel laid out for the R0001 can move to R0002 without changing the rail footprint or the wiring plan, only the contact assignment. A second ABB auxiliary, 2CDS200912R0001, also carries 1NO+1NC but on an 8.8 mm housing from a different family — it is not a same-footprint cross for the R0001 and any swap should be checked against the breaker's accessory slot geometry.