Everything That Can Go Wrong With A VFD

Added: 2026-05-06

[00:00:00]Look at all those pretty VFD cabinets.

[00:00:02]And they're controlling these big boys.

[00:00:04]But you already knew that if you watched my last short video where I had issues with one of them, but that was just the tip of the iceberg. This is where it actually started. The display was blank, but I clearly had control power according to the push to test light. So, let's open her on up and see if we can hurt ourselves. Based on the state of that bypass, I'm not the only one who's tried. Looking inside our cabinet, we got a 250 amp circuit breaker going to a fuse block. Looks like Cphase has been getting a little toasty. And then on the other side, we have the variable flagagillator itself, plus the line and load reactor.

[00:00:39]Very fancy. And finally, we have all our controls down on the bottom right, including this wire, which caused a lot of comments in my last video. It does look burnt, but it's not. It's covered in what looks like cutting oil. Probably from the electricians running the pipes.

[00:00:53]I don't know. There's a few things in here that have oil on them. But overall, a very clean cabinet for being about 10 years old. Went ahead and tested voltage on the load side of our fuses, and oddly enough, they're all good. I mean, they look like crap, but the fuses are not blown. Make sure you always check 480 and 277. If you just check phase to ground, you might read through a transformer or something and get a bad reading. Always check phasetophase. I also checked voltage on the drive itself just to make sure that the power was making it through the line reactor, and it was. But even though the power is still going through these fuses, we obviously need to do something about them because it's only going to get worse. Broke out the custom prosthetic handshaped fuse pullers to get them out.

[00:01:36]There's Cphase. Looks like it had been arcing for a while. I'm not sure if it was the fuse holder itself that was loose. It caused everything to heat up or if it was a loose lug that caused the fuse holder to heat up and loosen up.

[00:01:48]But either way, it doesn't really matter. This thing needs to come out.

[00:01:51]The Cphase lug actually loosened right up. I was surprised. A lot of times when these burn up, they seize up, too, and it becomes a total nightmare. But it loosened. Once I got that removed, I went ahead and taped up the wires. Even though the breaker is off and locked out, if someone decides to get too crazy and turn this on for whatever reason, at least there's less of a chance of it blowing up. I locked this out on the local disconnect or breaker or whatever.

[00:02:15]But I also turned it off upstream in the MCC because you really can't be too careful. Plus, since I'm working in this cabinet, I didn't want anything in it to still be hot. In terms of replacing the fuse holders, I did decide to use a different design. These actually allow the fuse to be bolted on. Plus, I am not going to be reusing mechanical lugs because of that high strand wire. I want to use crimp lugs. So, this fuse holder also accepts crimp lugs. I got all my hardware, stainless steel, for no good reason. perfectly fitting washers, my taps, lugs, everything should be good to go to replace this. Comment below if you hate my split washers. I hate everything.

[00:02:55]As I mentioned before, they did use high strand wire for most of the large power wiring in this cabinet, and that's why I'm using crimp lugs. That being said, there's mechanical lugs all throughout this cabinet and all throughout all the other cabinets. A lot of mechanical lugs, especially the standard like set screw style, are not rated for high strand wire, but they're all over the place. And I don't really think that's why this failed. I think it was just an actual loose connection because only one of them failed. Only one lug or one connection failed. Now, should I tell them we need to replace every connection that's not rated for high strand wire?

[00:03:30]No. Because this pump has 38,000 hours on it, and it took this long for a single connection to burn up. Now, is it proper to have those lugs? No. But does it work? I feel like you have to say yes. If it's been running this long and only one connection burned up, and probably not because of that, it it works. So, not exactly going to go through and replace tens of thousands of connections just because they're technically wrong. Most facilities do not have the downtime or the money to let you do that, but at least we'll do it the right way with what we're replacing. And speaking of replacing, I am going to have to cut the ends off of these wires because I'm going to have to shorten them. So, we're going to print some nice fancy new labels for them. And we are going to be using our old Greenley cutters. I left my other cutters at a job. Going to have to break out the old Greenleys. They're still good. They still work. And they even still work on this high strand stuff. I will be using my preferred labeling method, which is color code plus printed label plus clear heat shrink. Some people have had concerns in the past about the clear heat shrink, whether it's rated for this or not. It is rated for this purpose. I think it also makes everything look super clean. I don't really need corrosion resistance here.

[00:04:40]It's just to keep the label secure and look nice. It also insulates the connection, keeps you from touching it as easily. I'm also using my single point crimper, which people hate, but I'm going on like seven or eight years of using this single point crimper, and I have to maintain a lot of these connections years and years after they're made. So, I would know if they burned up, and I've never had a single one burn up. So, you can't really argue with the results. I mean, it doesn't look as good as the symmetrical like eight-point crimp, but it works and it is very easy and you don't have to worry about what size die you need. Also going to add a little slathering of my copper shield just to help that connection, help any future corrosion. The distribution block is an aluminum block and the lugs are tincoated copper.

[00:05:24]Anytime you see me using crimp lugs, they are tincoated copper. I know some people think they're aluminum. They're not. They're copper. There's our old wire looking crusty as hell.

[00:05:34]>> It's all old and dried out like that man right there.

[00:05:38]>> Luckily, I was able to trim it back far enough to get to good wire. Maybe I should have replaced the whole wire, but when I trimmed it back, it looked fine.

[00:05:46]I also actually put a printed label next to my fuse block of what the torque specs should be. I torqued my large lugs and I went ahead and marked them with the cross check so I can tell if anyone's been messing with my stuff. Why don't you back off my lugs, punk? Sorry.

[00:06:02]Sometimes I get real passionate about my crimp lugs. Now that that is done, I think we should get a new Cphase fuse. I mean, it still has continuity. It's not blown, but uh it'd be nice to have a new one. So, naturally, I went in a box that did not say fuses. They have a lot of spare parts at this facility. And thankfully, they also had a bunch of fuses, even though they were in a box not labeled that, but you you just got to look around sometimes. There's our fuses all installed and torqued down.

[00:06:28]They definitely don't have to be very tight, but there's a lot of surface area between the fuse and the block. So, that's why they don't have to be that tight. Plus, you really don't want to tighten these too much because sometimes the studs are made of brass. Even though they look like steel, they're like zinc coated brass, and you will snap them off in a heartbeat and make yourself cry.

[00:06:46]So, just just follow the torque specs.

[00:06:49]It's our old fuse block. There's really nothing wrong with those fuse blocks. We have them all over this facility, and this is the first one that's burned up.

[00:06:55]It was probably just a loose connection.

[00:06:57]There's nothing actually wrong with using them. I just prefer the bolt style. Of course, everyone who has to replace these fuses in the future and has to unbolt them will hate me for it.

[00:07:06]So, you're welcome. Since I made a pretty big modification, I did check continuity to ground to make sure nothing will blow up because that would be bad.

[00:07:16]All right, power is back on. on. As you can see by the lights, and what a surprise, the display still doesn't light up. It's almost like we didn't actually fix that problem. We've been focused on something else the whole time, and the drive still doesn't work.

[00:07:30]What a surprise. Looking at the drive closer, you can see that the control unit doesn't even have any lights. So, that's probably not a good sign. And I figured, well, the drive had power.

[00:07:41]Nothing tripped. Maybe the control unit is bad. Seammens divides their drives into like three parts. the power module, the control unit, and the interface.

[00:07:49]Power module is like the drive itself, all the big stuff. And then this is the control unit, which is the brain. And then the interface is your IOP or your display, whatever. So, I did find an spare one of those as well in the box of mysteries. I'm just going to pop the old one off, lean it down, and throw this one on. And if it lights up properly, it could just be a bad control unit. I'm generally not a fan of these Seammen's products because I'm too dumb to understand what the Germans want me to understand. But I am a fan of how they made the drives kind of modular because you don't have to always replace the whole thing. That being said, I probably have to replace the whole thing because this control unit is just having a disco party, which is also not good and I've also never seen. So, let's just turn that back off. Look for a whole new power module. Looks like we need a 100 horsepower power module. And luckily in the room of lost toys, they do have three of them and they're from 2018. So, I'm actually grateful because they don't make this style power module anymore.

[00:08:47]And if I upgraded it to the modern style, it would be more work. But since they got them, I'm going to use a mouse poop and all. And you're probably wondering, why are you putting it in your van? And it's because it's old.

[00:08:58]It's from 2018. These capacitors need to be reformed according to Seaman's specs.

[00:09:03]This is my capacitor reformer that I built a while ago. I did make a video on that. I got her hooked up at 25% voltage for 2 hours, then 50, then 75. There's the inside if you are interested. So pretty. And after I crank it all the way up with the variac limited by resistors, I give it straight 480 for a while. Make sure it doesn't blow up and we're done.

[00:09:27]So it's kind of a whole day ordeal. But when it's this old, you don't want to turn it right on. If you slap 480 onto this thing from 2018, it's probably going to literally blow up. I have seen it happen before. So uh I I'd rather be cautious. Also, there's much easier ways to reform the capacitors. I just like to over complicate everything. And since I have that big machine, I like to use it, but you can do it on site with a control transformer 120. There's a lot of ways to do it. I did get curious after I began to take it apart. I wanted to see if it was still producing DC, and it was. I got 680 volts on the DC bus. I also did a diode check later in the video. The seaman's recommended diode check to see if the internals are messed up. And the diode check tested good. So, it must be really a control power issue, but I can't really repair that. So, the whole power module is coming out. I also wanted to show you that this thing takes forever to drain down when it's turned off. Now, you probably think, I know that it's a drive, but if you take the control module off of one of these, the control module is one of the things that drains the power down from the capacitor. So, if you don't have that control module on there, it takes almost twice as long for the capacitors to drain down. So, just be cautious. If you're used to waiting 2 minutes for drive to power down, wait five if you don't have anything on there that actually drains it down. Someone was nice enough to install these washers on the bolts. So, I couldn't just lift the drive up and pull it off. But, if you take them off one at a time, you can remove the washers, put the bolts back in without the washers, and then you can just take it right off. So, really wasn't a big deal. There is the old drive and the new drive. As you can see, they are identical.

[00:11:03]>> Are you twins in real life?

[00:11:05]>> No.

[00:11:06]>> He had a lot of work done. You know, it's a little like this >> because uh it's kind of the point. But getting the new drive in wasn't too bad.

[00:11:14]This can be awful if you have like a big 2, three, 400 horse drive. But 100 horse in a spacious cabinet isn't too bad.

[00:11:22]Thought it was funny with these lugs. I thought maybe they had special lugs to go on the drive cuz they have that rounded port in there, but they clearly just ground the edges off these mechanical lugs, which I honestly I respect. And also, they're not burning up. So, for now, they're going to stay.

[00:11:37]But really, they should have bought crimp lugs with rounded edges that are actually meant for this drive. Once I got the power module all installed, wires snugged up, I actually put the existing control unit back on that wouldn't power up at all, cuz I thought maybe the power module was the reason it wouldn't power up. And if I can just slap the control unit back on, everything will just start working. I don't even have to move the parameters over. It should already be configured.

[00:12:00]But of course, no lights. So, I'm pretty sure whatever caused the control unit to burn up or whatever caused the power module to burn up also caused the control unit to burn up. So, pretty much losing every part of this system. After that, I reverted back to my out ofthe-box control unit that I tried on the other drive, the disco mode control unit. And that one finally actually powered up properly. You can see it got a bus fault flashing because it doesn't have any parameters. But now I have to move all the wires over. Don't forget your dip switches in the control unit.

[00:12:31]That will mess up your analog signals if you forget them. I have chased those problems for way too long in the past.

[00:12:38]And I cheated. I pulled these terminal blocks off. I I don't know if you're supposed to do this, but they come off.

[00:12:44]So I just took them off and snapped the old ones back in. These are not set screw connections. They're they're spring connections on the wires. So, it's not like they should have loosened up. I did pull on all of them, make sure they're tight. And I didn't add fererals to the wire because fererals won't fit in these connections. And it's not because of the insulating sleeve on the fereral. It's just the diameter itself.

[00:13:04]If you put a fereral on a 16 gauge piece of MTW, it will not fit in those terminal blocks. So, I just don't use them. I did have difficulty getting the parameters set into this drive, the existing parameters set, which was annoying because it's the same age equipment with the same firmware and everything. I had to break out the IOP2.

[00:13:21]Had to get it out of a different drive with the same parameter set. I compared them to make sure it was accurate.

[00:13:26]Compared motor data, all that stuff, and it turned on, so that is good news. It is hard to see it running because you can't see the pump itself, but I did my best. Here's the motor. And if we look in the forbidden cage, you can see the shaft is in fact going roundy round. So that is good. I also had a seal water issue, but you already saw that. And while I was at it, I checked the fans.

[00:13:50]They weren't running. They had voltage.

[00:13:52]They weren't spinning. These fans are hot garbage. If you ever have to work on these, I'm sorry. Do not buy them. Buy a different brand. Buy a different style.

[00:14:03]Buy something that fits in the same hole. They suck. They suck bad. the the the clearances are too tight and the plastic warps so they drag and you have to adjust the crap out of them. I've been complaining about this for too long, but I can't stop. It just made me so mad. But I replaced the fans. I guess that's the moral of this story. And the final issue I had was the escape button on the IOP did not work, which also drove me insane when I was trying to download the program. So, I did replace that as well. You just got to make sure that you re-upload the parameter set onto the new IOP or you will lose your copy of the parameters. Even pulling this plastic off didn't go very well.

[00:14:42]It's just that this job kind of fought me the whole time. I was about ready to set this pile of parts on fire, but uh I didn't. So, there it is. The new drive, which looks identical to the old. I even labeled when it was replaced so someone can be shocked when it dies next month.

[00:14:57]And I also tried to see why it died. And just like with the soft start video, I didn't find a whole lot. And I also don't know what I'm looking at. People were worried about the capacitors in the soft start. Look at the capacitors in here. Um, some stuff definitely looked like it got kind of hot with the conformal coating, especially this bottom circuit board. I don't know if it's supposed to be the color that it is, but the smaller circuit board definitely looked like it had some heat on it. So, I like I said, I think the power portion of this was still working.

[00:15:27]It was still creating DC, but the control side, something went wrong and it burned up all sorts of stuff. So, in summary, we had a burned up fuse block, we had a bad power module, we had a bad control unit, we had a faulty IOP, we had issues with the seal water, and we had two bad cooling fans. But the good news is I did leave you some spare parts in the cabinet. And hopefully this thing runs for another 38,000 hours. I doubt it, but maybe. See you on the next one.