SIRIUS safety relay Basic unit Standard series electronic enabling circuits 2 enabling circuits plus 1 signaling circuit Us = 24 V DC screw terminal safety relays SIRIUS 3SK1 for autonomous safety applications. The 3SK111 Standard basic units are characterized by simple, variable functionality and thus offer an economical route into the world of safety relays. They are ideally suited for safety functions with just a few sensors and a few enabling circuits. These devices have extensive worldwide approvals and are therefore ideally suited for global use and export. The devices are available as 24 V versions or with a wide voltage range, relay or semiconductor outputs, and all with either screw-type or spring-type terminals (push-in). Extensive accessories such as sealing covers, push-in lugs for wall mounting and coding pins make handling easier. The 3SK safety relays are replacing the proven 3TK28 series. Safety is a SIRIUS business.