Siemens 3RH1921-1CA10 SIRIUS Auxiliary Contact. SIRIUS Auxiliary Contact, Switch Block, 690 VAC, 6 A, 1 Contact, 6 kV Contact Resistance, Snap-On Mount, 10000000 Cycles Operating Cycles, -25 to 60 deg C Operating, For Use With: Contactor Relay and Power Contactor/Switching Motor, 38 mm H x 10 mm W x 51 mm D. Additional Description: SIEM-3RH1921-1CA10 AUXILIARY FRONT, 1NO. Catalog Description: AUXILIARY SWITCH BLOCK DIN EN50005 FOR CONTACTORS FOR SWITCHING MOTORS 1 Pole, 1NO Screw Connection.