RA4 interface relay is designed to receive 24 V DC signals delivered by PLC’s or other sources with a low output power and to restore them with sufficient power to operate the coils of the relevant AF09 ... AF96 contactors or the NF contactor relays. RA4 interface relay is made up of a miniature electromechanical relay equipped with a N.O. contact and with a low consumption 24 V DC coil. The interface relay coil is controlled by the PLC while the N.O. contact ensures switching of the power contactor. Coil switching gives rise to overvoltages which have adverse effects on the electronic devices, insulators and, more generally, on component lifetime. The RA4 is protected from surge thanks to the built-in surge protection of AF09 ... AF96. Furthermore, the RA4 is protected against relay pole reversal by a diode inserted between the E1 and E2 input terminals. Connection The "E1+" and "E2–" input terminals must be connected, according to their polarity, to the PLC-output. The RA4 is equipped with two terminal pads for connection to the A1 and A2 terminals of the contactor coil. This coil is supplied between the A0 and A2 terminals of the RA4. Mounting Remove the coil terminal block from the contactor and clip the interface relay without any screwing operation.