Triplex Pump Control Using Cost-saving Alternating Relays

Posted: 6/29/20 | Alternating Relays

Eliminate the PLC and Save with Macromatic ATP Series Relays


ATP Triplexor eliminates the PLC, saves space and labor, with no programming.


Macromatic Triplexor Relays save panel space, reduce labor, with no programming.Macromatic.  Specific-purpose ATP Series relays are ready to go right out of the box. These relays are pre-programmed for various triplex and duplex pump control applications.

Basic Triplex 3-Pump Control

The LEAD Switch closes energizing Load 1. As long as the LEAD Switch remains closed, Load 1 remains energized. If the LAG Switch closes, Load 2 is energized. If the LAG2 Switch closes, it energizes Load 3. Each load is turned off in sequence as the switches are opened. The entire cycle is then repeated, but with Load 2 energized first followed by Load 3 and then back to Load 1.

Sequence On-Restart After Power Outage

When more than one input is closed upon power up, the relay stages the startup of each pump to reduce the risk of brownout damage and overload trips caused by combined pump inrush currents.

Runtime Balancing Logic

For optimal pump reliability, the runtime of all three pumps should be balanced. In operation, run times can vary depending on conditions. If the runtimes of the pumps get too far apart, a selector switch on the unit can be used to lock in the least used pump as the first to start everytime. This will allow all the pumps to have equal runtimes as the maintenance department makes these adjustments.

Out of Sequence Input Protection

Floats or other level input devices can become stuck or damaged and operate out of sequence or not at all. This can result in unbalanced run time, reduced pumping capacity, and overflow. The Macromatic Triplexor Relay recognizes fault conditions and provides indication to the maintenance personnel using its status LED indicators.

Easy Downtime Maintenance

If a pump needs to be removed for maintenance or replacement, the Macromatic Triplexor unit can be converted to a Duplex alternation mode with the turn of a switch.

60% Cost Savings

Using Macromatic Triplexor relays eliminates the need for PLC hardware and selector switches as well as the labor associated with wiring and programming. This can reduce costs by 60%.