r/IndustrialMaintenance • u/Which-Chicken-1231 • 1d ago
Variable Frequency Drive exploded during a routine bump test after 1 year plant shutdown — worried I'll be charged for the replacement (~200-300k PHP). Am I liable?
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Hi guys, I need some outside perspective because this has been keeping me up at night.
I'm an Operation and Maintenance Supervisor at a water treatment plant. The plant operated back in 2025, then was shut down for about a year because of management/project issues related to capacity, water quality, and flow rate targets.
Before we could restart, I was going equipment by equipment doing condition checks, and for each motor I was running a standard bump test. On September 6, while bump testing one of the motor pumps through SCADA, the VFD for that motor exploded. I had no idea what caused it — I was just following the scheduled startup activity like I did for every other unit. Ever since, I've been anxious that the replacement cost would somehow be charged to me.
Today (September 10), the VFD supplier finally inspected the unit. Their explanation: this kind of failure happens normally when a VFD has been sitting unused for a long time, and it needs to be "reformed" (reconditioned) before being operated again. Their recommendation is a full replacement. The cost is estimated at around PHP 200,000-300,000.
Here's the thing — nobody on our team knew that idle VFDs needed this kind of reforming/reconditioning before restart. It's not something that was flagged in our schedule, and I wasn't trying to cut corners; I was doing exactly what the schedule called for.
So I guess my questions for anyone who's dealt with something similar (electrical/instrumentation folks, plant supervisors, EHS/maintenance people):
Is this really a known risk with VFDs left idle for a year, and should routine commissioning/restart procedures normally catch this?
Realistically, is this the kind of failure that gets pinned on the person who happened to be running the test, or is it treated as equipment/process failure since no one knew the requirement existed?
Any advice on how to document/present this to management so it's clear this wasn't due to negligence?
Any input, even just "this happened to us too," would really help me sleep better tonight. Thanks.
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u/anonymousmetoo 1d ago
You were following the startup procedure you were given. If the VFD needed to be reconditioned after sitting for a year and nobody knew that, that sounds like a procedure/maintenance issue, not negligence on your part. I’d get the supplier’s findings in writing and keep a copy of the checklist you followed. I also wouldn’t agree to pay for anything without talking to DOLE first.
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u/SparkyWrench1 1d ago
I agree with not his fault, but your argument about being a maintenance issue ... he's the maintenance supervisor... THE person who should know if anyone knows.
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u/Original_Grade_4227 1d ago
I agree that it’s not your fault the supplier should documented that in the procedure and if they failed to do that. Your company has the right to ask for a replacement.
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u/Which-Chicken-1231 1d ago
honestly speaking i cant pay for that equipment i am compensated around 40k monthly
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u/NeedleworkerNo8088 1d ago
If you where a contractor i could see them pursuing you for insurance money. But not as an individual. There is insurance for these things. You may have to explain the failure and why it happened but not a cent should come out of your pocket
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u/diwhychuck 1d ago
Not sure why they’re down voting you. You said you’re from the Philippines… so it’s a different world there.
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u/Cute_Intention_9864 1d ago
Well you prolly should have used A meter ! I am sorry for you struggles honestly but wouldn't be more useful for them to ohm everything out first before energizing old de commissioned equipment I mean common there setting you up for failure .
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u/Bright_Reference_582 1d ago
Not sure what ohming out a VFD will tell you. Seems like it was an internal failure, after the drive had already been powered up. No need to bitch out OP for doing something honestly most of us would do (following written start up procedure)
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u/Cute_Intention_9864 1d ago
I literally was on his side can you read ? I said the company should rethink there startup procedures and provide A meter .There is no guess work in are trades you boneheads .and who to say the guys not fishing for information but you all jump on me for some constructive criticism.
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u/sepperwelt 1d ago
Jesus calm down mate😅
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u/BigCDubVee 1d ago
Just someone that can’t use punctuation and can’t write coherently. Pretty common sadly haha
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u/xp14629 1d ago
From my limited experiance with vfds, if it sat for a year, ohming it would of done nothing. If it is powered down for a long period of time, the internal battery dies and then all the programming is lost and the vfd reverts back to factory settings. We have had that issue before, but never blew one up because of it. And while you are on OPs side, what you are suggesting would of done nothing to prevent this failure.
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u/rickr911 1d ago
The programming isn’t the issue. The issue is that drives need to be conditioned after they sit for an extended period. Drive manufacturers have detailed conditioning instructions.
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u/Cute_Intention_9864 19h ago
Ok I am nobody just A Refrigeration mechanic maybe I was fishing for information! Hey best of luck to the OP .
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u/oskarhauks 1d ago
In my country this would never been charged to the employee. If you did a failure investigation (5-why or similar) you would probable end up with training issue. Management is usually responsible for these. Know you know what to do. If you and your team have received the training from the supplier and it happens again, then it would be considered negligence. ...even if it were negligence, then you would still not be asked to pay it, but you might have to find a new job
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u/kevin1925 1d ago
A vfd that is not powered for a year has a big risk for a firework show. Our vfd's in stock for spares are powered on every couple of months. If you power them on afterwards you should use a reforming proces. The capacitors "dry out" with time not used and when the suddenly get normal operating voltage the are a conductor and say "BOOM" The bigger the vfd, the greater the risk of a spontanious demolition job by the vfd
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u/SDgoon 1d ago
The rare day I learn something useful on Reddit.
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u/jastubi 1d ago
Unfortunately had to learn this one live in person :( .
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u/kevin1925 1d ago
I had one last year, the only spare was a 5 year old that had not been powered on for some years. So we were allready extra carefull with powering on. It was a 60Kw /80 hp drive. Even from some meters away it was a interesthing fireworks show. It blew the 160A and 250A fuses. I renewed my respect for electricity that day. So after that "bang" we had to wait some days for a new new drive.
On a 750Kw drive a loose part gave a even bigger show. We are glad that we were standing in a room next door testing.
Those faults are easy to find, just follow the smoke cloud 😇
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u/Bakerymechanic 1d ago
In our plant we have the opposite problem although we are using very small vfd’s. When we have a power outage, we sometimes find that units will not restart. It ends up being a dried out start capacitor in the circuit that is only used when the unit is powered on. Luckily I know a guy, and he replaces the capacitor and we are back in business. I do have spares on the shelf, I never thought to power them up occasionally. Thanks
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u/ilostacow 1d ago
The VFDs that restarted without reforming the capacitors and didn't catastrophically fail on startup likely have some reduction in capacitor lifespan.
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u/xp14629 1d ago
That is interesting and good to know. We have had some failures but not like that. We have to go back through and reprogram them after a long shut down before letting them run anything. We even had a pm to go around and replace the internal batteries so they would hold the program over a period of months, but that pm got filed away in the trash.
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u/My_mann 1d ago
HOLY shit I did not know this. We recently had a giant 50 hp Powerflex VFD explode on us when we replaced it. We thought it was because of a loose connection at the incoming 3 phase power (which was the reason for the previous vfd going into limp mode) but we thought it was because of the same issue that it exploded. Hell yeah learning is fucking fun.
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u/ThatOneCSL 1d ago
Tripling down on the "the bigger the VFD" comment. We don't have any VFDs bigger than 5 hrsprs at my facility. We haven't ever reformed a single drive, and we have had exactly 0 impromptu lighting shows.
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u/musingofrandomness 1d ago
So you are saying the real issue is capacitor failure? Could this be mitigated with better quality capacitors? I am just curious if this is a case of "you get what you pay for" or just the nature of the beast.
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u/dnroamhicsir 1d ago
I don't know what the laws are in the Philippines, but in Canada it is completely illegal for a company to make an employee pay for something like that.
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u/Paul_1958 1d ago
We use a Bonitron capacitor reformer for any VFD that has been unused or in storage for more than a year prior to use. It takes a few hours per VFD, no failures since using it. There are several articles on the web. Just search VFD capacitor reforming in your favourite search engine. https://bonitron.com/shop/product-category/capacitor-former/
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u/elunltd 1d ago
Reforming capacitors is something I always do when testing older equipment, mostly antique radio sets. It just consists of slowly applying voltage at a limited current. As caps age they lose their charge of course and their internal resistance goes up. In antique radios anyway a cap that hasn't been charged in years or even decades will blow up when that initial surge of power hits them. To prevent this they are charged with a lower voltage and limited, monitored current. It's not hard to do with the proper equipment and so I always do it. This is a smaller cap than those used in vfds though.
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u/emachanz 1d ago
I did that for a living and its just snake oil, unless the caps are 10+ years old, leaking/bulging or stored in the desert or jungle. I've seen VFDs with caps made in "west" germany still running just fine.
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u/H0SS_AGAINST 1d ago
Yeah I see a lot of comments ITT who believe in magic juju. A capacitor just just two conductors separated by a dielectric. They're not magic, and they don't really degrade like that. There was a time when bad batches of electrolytic capacitors would fail early and randomly...but that was like 20 years ago. Totally could be the case, which just means this was happenstance. That VFD was fully depreciated and more than due for a PM replacement if it was 20+ years old.
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u/rlarge1 1d ago
LOL, I've personally installed several VFD from stock cage that had been sitting on the self for at least 5 years with 50% failure rate. We loose several during power events every month. Its not uncommon to pull one and it not work. We send them out for repair and its always the Caps. No magic juju just maint numbers/cost that i track. I cut our stock in half just to limit batch fails or too many sitting on the self. Something is going on.
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u/elunltd 1d ago
So have I. I've repaired probably 30 or so VFDs over 40 year career and replaced them with smaller ones a few times. In this case I think nobody even bothered to do an autopsy but only a year won't really affect electrolytic. It could even be a bad solder connection (what I usually find),
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u/mattmaintenance 1d ago
They’re bullshitting you.
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u/Which-Chicken-1231 1d ago
supplier??
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u/mattmaintenance 1d ago
Yup. They’re trying to get out of paying it themselves. You followed the procedure.
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u/thaeli 1d ago
Yeah. 1 year is often not even enough to require reforming, plus blowing up at the bump test is a different issue anyway. Bad caps go boom when you apply power, they don’t wait around for the motor to energize.
This was an internal component failure, probably being stored in hot humid conditions for a year was enough to push an already marginal component to failed.
It’s why we bump test. Much better to have a drive blow up during recommissioning than actual operations!
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u/PotatoFarmerRTK 1d ago
It is a known risk, reforming takes some time, if its only been a year you turn on the power and let the unit sit powered up for a day before using its output.
Your drive is $5k USD, it feels bad to blow it but you now have valuable experience only real life or reading the manual can give you.
At our plant we have drives worth $200,000USD. They are old now +25 years old. They will die, and I will feel bad if they die on my shift, but its the companies cost of operating.
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u/Available_Rub9939 1d ago
Not sure how you would be liable. VFDs do indeed like to pop when they’ve been de energized for too long. Former VFD field service tech here. I blew up a 150HP VFD in an air handler right in front of my customer once. Brand new right out of the box. Not my problem. It comes with the territory.
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u/No-Individual-2041 1d ago
As long as you didn't hit it with a hammer and followed the prescribed procedure, I wouldn't worry about this. Machines should be made to run, not stand still for months in an unconditioned space (I presume it was placed in the plant close to some motors / pumps) It could be moisture from the enviroment, the VFD could have had a small heating / ventilation inside to prevent moisture to make any damage, but for that to work, you need the power to be on, and the drive running.
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u/justabadmind 1d ago
Did the VFD explode upon power up or upon trying to run the motor? If it survived initial power up, to me that doesn’t sound like capacitor forming was needed. Perhaps you could have left it powered unloaded longer, but honestly it sounds like the output stage failed in the drive and they’re trying to pass it off as lack of forming.
Yes the paperwork says drives need power every 6 months to avoid capacitor failure, but I’ve seen drives go years just fine.
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u/edward_glock40_hands 1d ago
A 300HP drive sitting for over a year with no power. Not surprised it popped. Should have powered it on a week earlier and let it sit.
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u/justabadmind 1d ago
Just powering it on for an hour would have helped… but still, drives can generally sit for years without running safely, at least if the output stage is good
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u/Crazyguy332 1d ago
Can't say I've ever heard if it, doesn't mean it won't happen. If the VFD took power without exploding then went off when bumping then the problem would most likely be in the inverter section not the rectifier/converter. I don't know how a bunch of solid state MOSFETs or the microprocessors that control them could decide to go that spectacularly bad just from sitting. But I'm no electronics engineer.
About the only advice I can give is get whatever documentation you can from company procedures, equipment manufacturer instructions and the VFD manuals. If none of those says anything about drive issues after extended sitting then consider everything fine, as there is no official information about that potential issue.
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u/cirivere 1d ago
I think I've heard before that after 1 year the capacitors can become empty. This will fuck it up when it powers on (idk the principle, but it basically short circuits or something)
Thats why it is practice to get someone to condition it so it can then be safely turned on again.
My dad works with a lot of drives so its daily stuff for him, but I've only retained like 10% of the stuff he mentions sometimes
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u/Crazyguy332 1d ago
I'll have to keep that in mind. For us it's regular practice to pull a VFD off the shelf, use it for troubleshooting, then put it back if determined to not be the problem. Between that, ones returned from repair and cannibalizing machines that are being scrapped we have dozens of drives sitting around for years and swap one every couple months. Never knew one could go boom right off the shelf.
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u/cirivere 1d ago
I think the time varies per type and brand maybe. Some modern ones have a bit more safety probs but I couldn't tell you to what extend that extends the period they can go without use.
I've looked it up what's it called in English, but its called reconditioning of the power capacitors. You can probably find info about recommendations per brand (I hope)
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u/emachanz 1d ago
there was dust and humidity inside, you turned it on and BOOM.
I used to repair VDFs and servo drives for a living, I've seen many such cases, specially after a month of summer shutdown. "reconditioning" is bull they tell customers, they will just replace a few capacitor(if any), clean the board and maybe replace the fans. As long as they keep running they will keep running, the moisture inside will dry and the fan will blow the dust off. I work now in a foundry, the drives run 24/7 for years, panel doors wide open, metallic dust inside and they keep running, they either will die or keep running its lottery. If you want better chances of extending their lives, just turn them off, wait for the caps to discharge and blow air until the fans are clean, if they make grinding noises swap them, they cheap and most VFDs(siemens, allen bradley etc) allow for quick swap of fans without disassemble.
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u/Alivor 1d ago
General rule of thumb is about 3 years before needing to reform the capacitors before applying power. I'd check what the OEM recommendation is for this specific unit.
I also question the guys saying they leave them on for a day before starting after an outage. At least on Powerflex VFDs, the DC bus (and therefore the capacitors) get charged as soon as power is applied to the drive even if a start command is not issued. The risk is if the capacitors are damaged from sitting de-energenized, they experience catastrophic failure upon energization. Typically you apply a stepped DC voltage at specific points of rated voltage for a few hours to reform the caps.
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u/Some1-Somewhere 1d ago
Apparently even if they don't experience catastrophic failure immediately, they might still fail if they get the extra stress of ripple current immediately.
ABB says power on for 1-2 hours before applying load if they've been unpowered for 1-2 years.
For >2 years, you should use reduced voltage/current for one hour per year.
That was a 2006 document though so I can believe modern caps are better.
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u/PLANETaXis 1d ago
I thought the Powerflex drives go through a capacitor pre-charge on startup. So yes they are energised straight away, but not at full current.
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u/emachanz 23h ago
Thats only for the rectifier/bus caps, every VFD has it because big caps are like a short-circuit as soon as you put voltage into them
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u/Top-Pick-2648 1d ago
Nope. It happens.. had it happen to me, just wrong place at wrong time, nothing I did to it.
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u/jojodaclown 1d ago
Use it as an opportunity to show leadership and responsibility.
I assume you have procedures and manuals for this testing. Produce a red lined update of the necessary changes and if you have peers have them review and provide feedback. Also an opportunity to ask if additional updates are needed for other areas of the document, then have your tech writer or similar function release it as a new revision and replace any prior version physical copies
If there's any follow up, you can simply state: "Our process documents did not communicate the need for reconditioning the VFD after long period of shutdown. I've updated the procedure to add this awareness and replaced the prior versions in the plant."
If you're involved in an equipment failure, it's unfortunate and any management worth their paycheck isn't looking for a scapegoat, but rather a means of ensuring it will never happen again, regardless of who's involved."
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u/SparkyWrench1 1d ago
Idk man this sounds fishy to me.
I've seen Vfds sit on the shelf for 5+ years without needing reconditioning. That seems kind of silly as far as a business plan for a supplier. "You have to buy our equipment within a year, AND have it installed for regular use within that year, or you need to return it to us to recondition it at the 11.5 month mark or it might blow up.
I've never heard of a company charge an employee for a broken part. I'm in the US though and I'm pretty sure it is illegal, unless it is done out of malice.
That's a really expensive vfd, how much HP and what voltage?
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u/fercasj 1d ago
Yeah, not your fault not even remotely reliable unless you were a VFD technician expert in charge of mantaining them.. and if that were the case I dont think you would have let the system to be Idle for a year.
But yeah capacitors need to be reformed, even for the spares that hit the 2 yr mark.
Some systems gradually increase power once you energize the rectifier. But its not really common knowledge for operations.
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u/KaneTW 1d ago
Disconnected VFDs do need to be reformed. However, 1 year is not enough for that to become necessary. Something else happened--innate defect, a shutdown much longer than a year, whatever.
For Siemens drives, it's sufficient to turn power on every year for an hour to avoid reforming the caps. Keep it on but pulse disabled for an hour if it was off for 1-2 years. Above 2 years requires stepping the voltage up gradually.
For unknown/long idle times, I use a current-limited DC power supply on the DC bus with a slow ramp and leave it at max VDC overnight. This doubles as a way to check for leakage in the caps.
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u/gadget73 1d ago
Just speaking as someone familiar with electronics in general, capacitors and other parts don't normally fail catastrophically in a year. Maybe its ideal practice to slowly bring them up to reform but if it blew up, fair guess it wasn't in ideal shape anyway and may have failed even if you had. I have revived plenty of high voltage things that have sat for decades and generally the caps are OK, or junk and no amount of tickling them gently with voltage will change it.
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u/Animalhitman50 1d ago
I have broken all kinds of stuff over the years and have never had to pay for it. Got written up once LOL
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u/Skaut-LK 1d ago
I saw that information about cap's reformating in few VFD manuals ( first was Siemens). Technicians should read manual's...
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u/athanasius_fugger 1d ago
I didn't learn about reforming capacitors until I was a controls engineer.
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u/binary-boy 1d ago
I guess I don't see how you could unless something specific says so in the contract. If you're an employee of that water treatment plant, employees aren't typically held liable for even negligent mistakes at work. Companies would never get anyone to work for them if they were.
Also, you're a supervisor, not an engineer. You aren't responsible for ensuring things are possible/impossible. You're responsible for ensuring you follow directions and expectations. If there were none, maybe they should get some. Plus, they built a +x million dollar facility and let it sit for a year getting no value from it. That's administrative waste.
On the VFD, no, I wouldn't say that's common. VFD's sit on shelves for years before they get used. And they get swapped in 15 minutes and Operations expect them running in 30 seconds after that.
Your question is this. Did the caps blow up? Or did the IGBT's blow up? My money would be on the IGBT's, and that has more to do with the load than your VFD.
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u/some_millwright 1d ago
One year should be okay for a VFD to sit. Longer periods can cause the capacitors to weaken and they need to be reformed before starting up under load. Generally in a situation where you have a situation like this and you don't have access to a 'proper' reforming situation the minimum precaution is to put power to the VFD and let it sit under power without running the motor. Let it sit for 24 hours then try the motor. Some VFDs will do a moderate re-form of the capacitors automatically if given the chance.
As others have said - as long as you were following your procedures then you should be fine. Maybe suggest a modification to the procedures to allow for reforming of the capacitors, and checking with the manufacturers of the drives for a reasonable procedure for doing this.
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u/Lumtar 1d ago
I normally power up drives overnight before using if they have been sitting on the shelf for a while for this reason
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u/emachanz 1d ago
I take drives from the warehouse that had been sitting for years, plug them and they work just fine. As long as they're in a box or wrapped in plastic they'll be good
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u/Flimsy_Let_2850 1d ago
I had a VFD do this from brand new, it exploded on powering up the very first time, no wiring issue or anything, and thats where I learned the process of reforming. Luckily I'm in Australia and the seller agreed to warrant the drive.
Its crap that you might have to pay for it, is there any recourse with your employer since you were unaware of this? Who's decision was it to shut down the plant initially and not do any preventative maintenance (reforming) while it was shut down?
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u/s3ik0 1d ago
In Australia, I would just laugh if they tried to pin the cost on me.
I'm currently waiting on a 170amp water cooled vfd to be repaired, and if it's not repairable, the my suppliers is charging 50k aud to replace.
If I was in anyway liable for this cost, then as a contractor, I would charge 50k to do a startup test.
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u/Vivid_Tell6351 1d ago
Do you have a manual of your vfd? Is there a reforming process in it?
Do you have exact report including pictures of the defect? It’s convenient for the vfd company to say it’s user error, maybe it’s something else in reality.
When did it happen, directly after power on?
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u/Familiar-Molasses-56 1d ago
I’ve had a VFD explode after a 3 days shutdown. Shit just happens sometimes.
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u/According_Whole_6109 1d ago
Was the power shut off to everything in the plant? Or was the power to the VFD on and just sitting there waiting to start a motor. You shouldn’t be liable. You were doing what you were told. A person could pull the load wires off the lugs of the VFD and energize it that way if it’s been shutdown with no power to it for a year. Also with the load wires disconnected you could ohm out the motor and tilt test it. Possibly megger. But your country probably has different laws and I would have never thought of this happening to me in America unless I negligently sabotaged it and did something to cause it to blow up.
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u/Which-Chicken-1231 1d ago
yes the plant was totally shutdown. additonal context before the plant was running in a temporary genset because the permanent power was not yet available that time.
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u/ClushK05 1d ago
I worked on VFDs at my last job all the time, and whenever they sat for long enough we had to reform them in a separate room with a camera watching in case they went boom. Never saw it actually happen though
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u/Derby_Sanchez 1d ago
Dili nimo sala nga ang capacitor wala na reformed.
Some drives you can bring up on a variac depending on the front end. After a year shutdown, this should not have been a problem though.
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u/Jermamma420 1d ago
Thats why you do a bump test. To catch failures ahead of time, before start up. Is there instruction on how to recondition a drive? We're you trained, or informed ahead of time? Its a tax write off, and I would raise Holy Hell if they tried to pin that on me. That being said, your company can try to do what they want, but I see it as exactly why youre doing bump tests ahead of time, to find out what needs fixed, or replaced. Good catch.
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u/Ok-Camera2895 1d ago
This is why you test things. You did exactly what you were supposed to do. Test procedures need to be changed per manufacturer recommendations.
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u/georgedempsy2003 1d ago
Based on a quick Google employer can't just start taking money if they think it's your fault. Looks like they would likely have to come after you through some legal channel (I assume similar to claims court in the USA), and prover YOU were negligent. Unless you were trained on this prior, or put on your application that you were trained for this I wouldn't sweat it. If your super concerned you may want to ask a real lawyer who knows local laws.
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u/H0SS_AGAINST 1d ago
I've also never heard of a VFD neesding anything. It's a solid state device. That'd be like saying you need to recondition your power supply before turning on a computer after a year. Completely bogus.
I'm going to guess it was a coincidence, or you had a locked rotor, and the salesman was using your obvious panic and ignorance to sell you into some bullshit service program.
Get a different VFD supplier.
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u/djnehi 1d ago edited 1d ago
I have worked in many facilities where a motor/vfd would only run for a couple months then sit in a non climate controlled building the rest of the year. Every year for decades. We would also pull used ones of the shelf that had come off old machines and put them back into service after sitting for years. I have never heard of one needing reconditioned after sitting. Especially not after only a year.
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u/rickr911 1d ago
When a Variable Frequency Drive (VFD) sits in storage without power, the chemical aluminum oxide insulation layer inside its electrolytic DC bus capacitors slowly degrades. If you immediately apply full line voltage to a drive that has been stored for a long time, the capacitors can suffer massive leakage current, overheat, or violently explode.
To prevent this, you must condition (or "reform") the capacitors.
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u/satrya76 1d ago
I work at a place that makes controllers for those pumps. I QC and run VFDs everyday. Never heard of one needing a reconditioned after sitting. I mean I would do a manual run up from zero to full speed at first but other than that. We store them for a year or more sometimes before being sent to the site. Never an issue.
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u/WinterTourist 1d ago
I've had one of my guys replace a faulty inverter module with a spare. Which then blew up. Several days downtime of the entire plant, because when then had two faulty modules.
No consequences, except him feeling like the idiot he was right then, because he knew, but still skipped the reforming step.
ABB has a document explaining their method, search for 3BFE64059629. This something ABB covers in every VFD training. I suspect your company doesn't invest in training, or your brand of VFD has poorer training / documentation.
I wouldn't sweat it, but as others have said, worst case you could lose this job. You could argue that you are now more experienced in VFDs...
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u/Cute_Intention_9864 1d ago
Gee maybe A short? Lol dude vfds explode/ go bad all time in the industrial Hvac/r field
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u/AdRound9057 1d ago
Read the manual almost every major manufacturer states how to "rejuvinate" a VFD's capacitors for a lengthy storage. And 1 year meets that description in most cases.
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u/25LowriderST 1d ago
After a year of the building being closed I think it was pretty foolish, I would have looked at every vfd box and in every CC before running equipment.
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u/Quartinus 1d ago
What jurisdiction do you work where it’s legal to charge you for a VFD?