Testing PLC equipment that got wet

Hello. We had our fire suppression system trip last week (while we were snowed out of the plant), and it sprayed so much water that our PLC cabinets leaked. Everything got wet on the inside and some of the equipment at the bottom sat in water (our fire water is potable water, FWIW). There are a couple of AB SLC5/05 racks, an AB Panelview and 3 CH Panelmates, plus multiple other smaller instruments, intrinsic safety barriers, etc in the cabinet. We've been blowing air on the equipment with a fan to dry it out. Is there a good way to test out the equipment before we apply power?

I don't know if you'd ever really know if it was completely dry. If your insistent on reusing the damaged equipment, I would remove each device from the control circuit and test it individually. Powering up the whole cabinet at once could make for some real entertaining fireworks.

@Steve:
We have small box with 200 volts light bulbs inside of it.
Something similar happened to us several year ago and we dry out power suplies, modules , cpus, etc. inside that box for several hours, temperature inside is 65 degrees celsius. We recovered almost everything except two analog modules.
As _dock_ said we tested every module individually.

I did dry out a couple loop controllers once that got sprinkler sprayed when the panel door was left open. Vents in the top of case let the electronics chassis get soaked.

The controller chassis could be removed from the case which was fastened into the cutout in the panel door. The case wiring could be dried with a hair dryer/heat gun.

The controller chassises were put in an electric oven at the lowest heating temperature (140 Deg F?) with the door cracked open to allow convection into and out of the oven.

The controllers fired up OK after drying in the oven for about 1/2 hour.

If you want to try in-situ drying, you might look at small propane 'salamanders'. Open the panel doors and move the salamander back far enough that the heat does not bake what it hits. The hot air flow will help move out the moisture that evaporates. Propane burns with little CO, mostly CO2, but you'd still need some outside air ventilation.

For circuit boards and most components generally water doesn't effect them. Blow them off, even put them in a low temperature oven for a few hours - under 125°F/51°C to not melt plastic parts.

Transformer windings, and motor armatures, however that get wet can do amazing things when powered up. These usually need baked until completely dry.

The only transformers in the cabinet are the 24V power supplies, and they all tested fine on the bench. The motor control is in a different building, so no problems there. We're putting a space heater in the cabinet door for a day to dry everything out.

bigsteve said:

The only transformers in the cabinet are the 24V power supplies, and they all tested fine on the bench. The motor control is in a different building, so no problems there. We're putting a space heater in the cabinet door for a day to dry everything out.

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Then I would just tell your apprentice to power it up and let you know if anything happens while you go get a coffee...........

If it was up to me, I would include the damaged components in the insurance claim. If the insurance company lets you keep them after settling the claim, use them to build a trainer for the maintenance crew.

I have a little different approach, turn your head and flip the switch, what does not work is bad what works is good (this is after you tried to dry it out)

We had a guy during a PM try and clean out the cabinet with compressed one time, had a few hundred relays, PLC, power supplies, drives, etc... you know just a standard cabinet for a large machine, 7 foot tall and 40ish feet long, know one saw him doing it and his intentions were good but it was weeks before we were up and running for more than 2 hours without some that stopped working.

My point is, I dont think all the bench testing is going to help, just let it run and let the machine tell you what failed

geniusintraining said:

I have a little different approach, turn your head and flip the switch, what does not work is bad what works is good (this is after you tried to dry it out)

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I think this is going to be how it is. We don't have the spare parts to replace the entire cabinet (including the time for untangling the 30 years of splices, patches and on-the-fly repairs). Everything is either low current 120VAC or 24VDC, and I already know the power supplies are good.

I would disassemble all the electronic equipment and put them in a drying chamber, which can be something temporary, a small space with a domestic heater and not well closed since the air has to be renewed so the humidity will be carried away.

bigsteve said:

I think this is going to be how it is. We don't have the spare parts to replace the entire cabinet (including the time for untangling the 30 years of splices, patches and on-the-fly repairs). Everything is either low current 120VAC or 24VDC, and I already know the power supplies are good.

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Well it pretty much seems like you had your mind made up for you, I'm very interested to see how all this works out. Good Luck and keep us posted!

Slightly OT---

We had a heat exchanger that is poorly located in a ceiling above an electrical room fail once and poured a lot of water through a very old 600 V distribution panel.
It tripped the mains and little damage actually happened during the initial event.
Against my best wishes and pleading to simply write this off now, it was decided to proceed with drying the breakers out. In an oven!!!! Production must go right.

Once all were tested and megged clear, power was applied to the panel and one by one, with a fiberglass pole and arc flash gear on just in case, the breakers were turned on. I completely expected a large explosion so we were well away form this thing. Myself still protesting the entire event and insisting the breakers are toast, we proceeded.

Finally all was powered up and on, no bangs. Until.... 15 minutes later, I'm walking through the electrical room, arc flash gear off at this point, thinking we dodged a bullet and I cant really believe this worked and then it happened. Luckily my back was to the panel and I was a good 8 feet from it. One of the breakers blew like a stick of dynamite! It scared the **** out of me. It was bad.

I said I didn't want to work on or near this death trap again.

Now there is a brand new distribution panel!

After circuit boards have passed thru the wave solder they then go thru a washer that is a small car wash. Some of that solder resist stuff is hard to remove so there is a presoak, then a soap, then a high pressure wash. This finishes with a high pressure rinse and air blast. The operator wears rubber gloves.
Since then I've taken dirty SLCs and I/O cards home and run them thru the dishwasher. So far they have all worked.

gas said:

Since then I've taken dirty SLCs and I/O cards home and run them thru the dishwasher. So far they have all worked.

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They go through a lot more than that... I worked in the CB industry for 15ish years and they are soak rinsed with water, acid, base and everything else they can find, the old days they did art work on them then then run them through sulfuric acid or hydrochloride to remove the copper and leave the traces

Please take a picture of the next time you send a SLC through the wash... thats funny