Abstract: An electrical relay is provided with bifilar windings defining a first coil and a single winding defining a second coil. Each of the bifilar windings is connected in series with an RC network and this circuit is connected in parallel with the transmission line. When an AC current flows in the transmission line and through the bifilar windings and single winding, this does not cause the armature to move. When a DC current flows in the transmission line, it flows through the bifilar windings but is blocked by the RC network from flowing through the single winding which causes the leg of the armature to be attracted to the bifilar windings coil thereby operating the relay.