The Siemens duplex motor controllers are specifically designed for industrial and commercial applications that require duplex controls such as duel pumps or blowers. They perform one or both of two distinct functions: duplexing and alternation. The duplexing function provides capacity for system peaking or above normal demand without having both motors running at all times. It also provides standby capacity for use when one of the motors is disabled.
Duplex motor controllers consist of two motor starters in a common enclosure.
Class 83 is a non-combination duplex motor controller.
Class 84 is a combination duplex motor controller with two separate disconnects or circuit breakers
Class 83 Non - Combination
Class 84 Combination
The alternation function reverses the lead and lag mode for the two motors in a duplex system. Upon alternation the first motor becomes the lag motor and the second motor assumes the lead function. The alternation is usually programmed to occur at any time both motors come to rest. The alternation function equalizes wear on the two machines and extends the life of seals and bearings.