The Model ALT alternating relays are used to alternate between two loads. The ALT is commonly used in duplex pumping applications to balance the runtime of both pumps.
The Model ALT-S is used in single high-level float applications. When the float switch opens, the alternating relay changes state, forcing the other pump to run the next time the float closes.
The Model ALT-X has an internal cross-connected relay and is used in dual high-level float applications. These floats are commonly referred to as lead and lag floats. The pumps alternate as in the ALT-S version but the cross-connected relay configuration allows both pumps to run simultaneously when both the lead and lag floats are closed.
These relays are also available with a built-in switch (SW option) that is used to manually force one of the pumps to run every time the float switch is closed. This is helpful when a pump has been removed for repair or for test purposes. In the case of the Model ALT-X-SW, the switch essentially forces one pump to be the lead pump, while still allowing the second to run when both floats are closed. All Model ALT relays have a built-in debounce feature that prevents the relay from changing state if the switch or float contact bounces momentarily.
The Model ALT-xxx-1-SW and
ALT-xxx-3-SW are used to alternate between two loads and are commonly used in duplex pump-up and pump-down applications to balance the runtime of both pumps.
The ALT-xxx-1-SW alternating relays are 11-pin octal base plug-ins, available in two different single-phase voltage ranges. The ALT-100-1-SW is used for 95-120VAC applications and the ALT-200-1-SW is used for 190-240VAC applications. Both models are designed for a single float input and feature two isolated Form C relays (DPDT) outputs with two LEDs to indicate the energized loads.
The Model 50R-400-ALT alternating relays are used to alternate between two loads, most commonly in duplex pumping and compressor applications to balance the runtime of both loads.
When used in single float applications, the alternating relay changes state after the float switch opens*, forcing the other pump to run the next time the float closes. When used in dual float applications, the alternating relay will allow both pumps to run simultaneously when the lead and lag floats are both closed.
