The RA4 interface relay is designed to receive 24V DC signals from programmable logic controllers (PLCs) or other low-output sources and restore them with sufficient power to control the coils of the AF09.AF96 contactors and the NF auxiliary contactors.
The RA4 interface relay consists of a small electromechanical relay with a normally open contact and a 24V DC coil with low power consumption.
The coil of the interface relay is controlled by the PLC, while the normally open contact ensures the switching of the power contactor.
When the coil switches, overvoltages are generated that have a negative effect on electronic devices, insulators and, in general, on the service life of components. The RA4 interface relay is protected against overvoltages thanks to the overvoltage protection integrated in the AF09.AF96 contactors.
In addition, the RA4 is protected against reverse polarity by a diode between the input terminals E1 and E2.