Helping PLCs Keep Their Cool

Programmable logic controllers (PLCs) are the ruggedized computers that 
run most automated manufacturing processes, from simple conveyor lines 
and pick-and-place operations, to more sophisticated machining and 
robotics applications. Though individual units are often quite small, 
PLCs are often installed in ganged enclosures and, like other types of 
computer equipment, they can produce a lot of heat. As a result, 
specifiers and contractors need to consider cooling options to protect 
against equipment overheating and failure. Hoffman

Chuck Ross

Programmable logic controllers (PLCs) are the ruggedized computers that run most automated manufacturing processes, from simple conveyor lines and pick-and-place operations, to more sophisticated machining and robotics applications. Though individual units are often quite small, PLCs are often installed in ganged enclosures and, like other types of computer equipment, they can produce a lot of heat. As a result, specifiers and contractors need to consider cooling options to protect against equipment overheating and failure.

In clean and naturally cool environments, simple passive-cooling strategies can involve designing enclosures with vents designed to allow hot air to escape and cooler fresh air to enter. But many applications require more active approaches to maintaining safe enclosure temperatures.

The first option is to encourage the flow of fresh air through the enclosure with a filtered fan. “Fresh air cooling is every effective in cool environments where the atmosphere is relatively clean, with low levels of suspended particulate matter,” says James Swanson, training manager for enclosure manufacturer Hoffman. These applications could include cleaner industrial settings, along with telecommunications and data-networking installations.

Closed-loop cooling solutions are more like small air-conditioning systems. Swanson says these products are necessary “wherever you need to cool the equipment below the ambient temperature and keep dust and moisture out of the cabinet.” This approach is well-suited to such settings as automotive manufacturing plants, paper mills, foundries and other locations where airborne pollutants could damage the enclosed PLCs.

Depending on the enclosure, specifiers can opt to mount either type of cooling unit externally or internally. External, surface-mounted units will increase the enclosure’s overall footprint and could be vulnerable to damage. Interior, recess-mounted equipment is more protected, but also will take up room within the enclosure, itself.


Photo courtesy of Hoffman