Siemens 3SK1111-1AW20 SIRIUS 3SK1 Standard basic units. Siemens 3SK1111-1AW20 is the exact printed commercial reference for a safety relay in the SIRIUS 3SK Safety Relays range. Siemens' official product description is: SIRIUS safety relay Basic unit Standard series Relay enabling circuits 3 NO contacts plus Relay signaling circuit 1 NC contact Us = 110 - 240 V AC/DC 50/60 Hz screw terminal.