Contactor relays are switching devices for control and auxiliary circuits and are used to control, provide signals and interlock switching devices and switchgear panels. The SIRIUS contactor relays have connection designations in compliance with the standard and use a connection system which is both time and cost saving — fulfilling the requirements from the field. They are designed for AC or DC operation and are available with screw or spring-loaded technology. The basic version of the contactor relays has 4-poles but this can be extended up to 8-poles using auxiliary contact blocks which can be snapped-on.