ABB RA5-1

RA5-1 is an interface relay designed to receive 24 V DC signals delivered by PLCs or other sources with low output power and to restore them with sufficient power to operate the coils of the relevant contactors. The RA5-1 interface relay consists of a miniature electromechanical relay equipped with a normally open contact and a low consumption 24 V DC coil. The interface relay coil is controlled by the PLC while the normally open contact ensures the switching of the power contactor. Coil switching can cause overvoltages that adversely affect electronic devices, insulators, and generally the lifetime of components. The RA5-1 is equipped with surge suppressors: on the 24 V DC relay coil via a diode and on the power contactor coil via a varistor. Furthermore, the RA5-1 is protected against relay pole reversal by a diode inserted between the E1 and E2 input terminals.