The Duplexer is used in control panels where tow loads are required to alternate to provide equal run time on the loads. The alternating action in initiated by a control switch, which is common with one side of the control voltage. The output contacts will change states each time the control switch is opened, thus alternating the two loads. The LED indicators show the position of the output relay. The ARA Series is the standard Duplexer providing automatic alternating sequence. The ARB has the automatic sequencing feature plus the option of locking it into one sequence. A three position switch permits the field selection of normal duplexing action, locking in the A-B sequence, or B-A sequence.