Siemens 3RQ1000-1HB00 Positively driven coupling relay in industrial enclosure 2 NO contacts / 2 NC contacts 24 V DC. Siemens 3RQ1000-1HB00 is the exact printed commercial reference for a coupling relay in the SIRIUS 3RQ range. Siemens' official product description is: Positively driven coupling relay in industrial enclosure 2 NO contacts / 2 NC contacts 24 V DC SIL 2 / PL c screw terminal.