Using fans to cool an Industrial Control Panel 10

[PaulKraemer]

Hi,

I am trying to design an Industrial Control Panel that can be a drop-in replacement for an existing control panel that has been in service in a machine control application since the 1990's. The existing control panel (and the machine it controls) still works, but many of the the components inside it (PLC, drive boards, temperature controls, etc) are obsolete and unsupported. We are afraid that the failure of one of these components would result in significant downtime if we are not prepared. For this reason, we are hoping to do a pre-emptive upgrade of the entire control panel.

Using the original control panel for reference, I am trying to select modern (equivalent or hopefully better) components for each control function. While I am certain the original control panel would be found to be far from UL compliant if it were inspected, I am doing my best to choose components and follow practices defined in UL508A for the new control panel. (I am in the process of reading UL508A after receiving some great advice in response to another question I posted on this forum recently).

The question I have now come upon is this... The existing control panel has three solid-state relays that are used to regulate the power applied to resistance heaters. The new control panel will have similar solid state relays. These solid state relays generate some heat inside the panel. In the old control panel, there are two filtered ventilation openings on the lower part of the control panel (one on each side). (The filters look like a metal mesh). There is a fan mounted dead-center at the top of the old control panel that sucks air from above the panel and blows it down into the control panel. The intake side of this fan has the same type of filter as that used on the sides.

I was just wondering if anyone here can comment as to whether this sounds like a reasonable way to keep the inside of the panel as cool as possible (without resorting to air conditioning)? Before I "felt" the direction of air flow, it crossed my mind that there might be an advantage in having the fan on the top of the panel suck air from inside the panel and exhaust it above the panel.

Any comments will be greatly appreciated.

Thanks in advance,
Paul

 

[PaulKraemer]

Thank you mc5w for your thoughts. I won't have to worry about cleaning the parts inside my panel because I will be building an entirely new panel and discarding the old panel (with all its components). I will pay attention to the condition of the field wiring that I will have to disconnect from the old panel and re-connect to the new panel, replacing any wires that need to be replaced.

That is an interesting point that a fan blowing air into a panel can have the side effect of spreading lubricant or anything that might be suspended in the air all over the inside of the panel. Luckily, I don't think this will be the case in my installation location. There will be a little dust, but I don't expect much more than that.

I do have a question about your comment that "The volute of a blower should have a drain hole drilled into it." I was thinking I would use a fan similar to the one below...

https://hoffman.nvent.com/en-us/products/enchf0916414

... I don't think I will need a more expensive or more complicated fan because the there is no evidence of over-heating in the existing panel I will be replacing and I am certain the new components in my new panel will be more efficient than the old components in the old panel. I am just trying to come up with the best strategy for locating the fans relative to my components.

Would you expect that a small fan like the one in the link about would afford me the possibility of drilling a hole into the "volute", or of finding a similarly sized fan that would come with a hole pre-drilled.

To be honest, "volute" is a new term for me. I googled it to get an idea, but I am not even certain at this point if all fans have a volute. I apologize for my ignorance, and appreciate your help.

Thanks and best regards,
Paul

 

[Hoxton123]

So what do you do when the fan stops / trips?

 

[EdStainless]

These look like simple straight through fans.
Blowers would have a volute. You drill a small hole in the bottom to allow drainage of any collected liquids.
I worked in a shop that was not heated much and we would have condensation collect in blowers.
In fact some of our control cabinets had heaters in them in order to keep them dry.
We never tried sensing if the fan was running, but we would put a high temp alarm on the most critical (or expensive) item in the panel. If it got hot then checking the filter and fan was step #1.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[RedSnake]

Change it. ;-)

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[jraef]

Something else to consider with the fan at the top blowing down:

In days gone by, passive /convection cooling of components was common, so as was said, it didn’t take a lot if fan power to overcome that. But a lot more devices have cooling fans in them now and I’d venture to say that 99% of them are blowing the fans UPWARD to take advantage of convection. So if you have things like drives and power supplies with cooling fans blowing Up, and your panel fan is trying to blow Down, you might inadvertently create dead zones in components where you get neither convection cooling nor fan cooling. I have seen this happen more than a few times in VFD cabinets.


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