Switching envelope — 1 A SPST-NO with DC control
The SRS1-A1D101: This is a single-pole, normally-open relay rated for 1 A continuous load current across a 5 V to 100 V DC load range. The input coil is driven by 4 to 24 VDC, making it compatible with standard 24 V PLC outputs or 5 V logic-level signals without an external dropping resistor. The 1 A rating at 100 V DC puts it in the signal-relay class — it switches low-power loads like PLC input signals, indicator lamps, solenoid valves under 12 W, or auxiliary contactor coils. Not sized for motor or heater loads; those need a power relay or contactor.
Socketable plug-in — field-replaceable, not PCB-mount
The SRS1-A1D101 uses plug-in termination and is socketable — it snaps into a relay base or socket, not soldered to a PCB. This is the standard form factor for panel-mounted control relays where the coil and contacts are field-replaceable without desoldering or board removal. For a maintenance or repair technician, socketable means the relay can be swapped in seconds with the panel live (assuming the circuit is de-energised). The scorch mark on a failed relay tells you which part actually died, and the socket lets you replace it without pulling the whole terminal block.
Series identity and category fit
Signal relays like this one are used in control panels, PLC output modules, and industrial automation circuits where the load is low-current DC — think indicator lights, small solenoid valves, or interposing relays between a controller and a larger contactor.