In my article last week, we discussed the critical first step of thermal management: Selection. We covered how to calculate heat loads and choose the correct cooling capacity for your electrical enclosure.
However, in my years of field experience, I’ve seen a recurring paradox: The sizing is correct, the brand is premium, yet the cabinet still suffers from high-temperature alarms.
Why? Because selecting the right unit is only half the battle. The other half is Application Engineering.
Today, let’s move beyond the spec sheet and dive deep into the installation realities that determine success or failure—ranging from how air moves to how water is managed.
1. The "Invisible" Problem: Airflow Organization
The most common reason for a "failed" cooling solution isn't a lack of power; it is a lack of circulation. We call this a Thermal Short Circuit.
Cabinet air conditioners operate in confined spaces packed with obstructions like wire ducts, transformers, and large VFDs.
What goes wrong?
If the AC’s cold air outlet is blocked by a component or installed too close to a wall, the cold air is deflected immediately back into the AC’s own return intake.
The Consequence:
The AC’s internal sensor detects the cold air and assumes the entire cabinet is cool. The compressor cycles off (or slows down) to save energy. Meanwhile, in the "dead zones" of the cabinet, your critical drives are overheating.
The Solution:
Check the Path: Ensure a clear "air corridor" exists from the AC outlet to the bottom of the cabinet.
Use Deflectors: If obstructions are unavoidable, use air diverters to guide the cold air toward the intakes of your hottest components.
2. The Loophole: Sealing and Efficiency
Industrial cabinet ACs operate on a Closed Loop principle. They are designed to condition the air inside the box, isolating it from the dirty, hot air outside.
But this only works if the box is actually closed.
Common Oversights:
Unsealed cable entry glands (the most common culprit).
Worn-out door gaskets.
Leaving the pocket on the door print holder empty (creating a hole).
If the cabinet isn't sealed, you aren't just cooling the enclosure—you are trying to cool the entire factory floor. The unit will run at 100% capacity continuously and still fail to hold the temperature.
3. The Hidden Danger: Condensation Risks
This brings us to the most damaging risk: Condensation (The "Sweating" Cabinet).
Many operators believe "colder is better" and set the AC to 20°C (68°F). This is a dangerous practice.
Why?
Dew Point: If the cabinet is not perfectly sealed (see point #2), moisture from the outside enters. If internal surfaces are cooled below the dew point, water droplets will form on copper bars and electronics.
Flashover: Water on energized components leads to short circuits and catastrophic failure.
Best Practice:
For standard industrial electronics, a setpoint of 35°C (95°F) is ideal. It is cool enough to ensure component longevity but warm enough to stay safely above the dew point in most environments.
Summary
A robust thermal management strategy requires looking at the electrical cabinet as a complete ecosystem.
Selection gets you the right tool.
Airflow Management ensures the tool works effectively.
Sealing & Settings protect the equipment from moisture damage.
Next Step:
If you have installed AC units but are still seeing "Over-Temp" faults on your VFDs, don't just buy a bigger AC. Check your airflow path first.
Do you have questions about your specific cabinet layout? Feel free to leave a comment or send me a message for a quick assessment.