An interfacing relay is an electrically operated switch, typically situated between two or more function components that are isolated from each other to prevent interference. They are widely used in control and protection systems of high voltage equipment.
Interface relays are similar to control relays in that they offer switching operation between low- and high-power circuits, but interface relays significant increase the isolation between any given input and output circuit.
Interface relays are highly resistant to noise and electromagnetic fields, and offer fast operational speeds. These characteristics make interface relays particular effective for use in high-power installations, where high voltage equipment generate frequent voltage spikes and interference.