OptiSpeed harmonic filter issues

[chillerguy81]

Just took over contract on a 400 ton Yk which we had lost two years ago. I visit the site and find the the breaker has been locked out since December by the previous contractor. Opened up the drive panel and find the filter trap assembly is fried, wires from the trap assembly burnt up to where the connect to the CT's. The three 50 mf capacitors check out ok but the other smaller capacitors and resistors are toast (some completly disintegrated). I'm trying to determine what caused the problem and what all components are bad besides the obvious.
I tested the VSD module and Harmonic filter module following the instructions in the service manual. VSD module checks out fine using the diode test method. When I checked the Harmonic filter module I'm at .401 vdc where I should have .36 vdc. The manual states that "if any one of the readings are not correct" the module must be replaced. My question is what kind of tolerence is there? Is .401 vdc bad? The opposite terminals go to OL as they should, if you reverse the polarity the same thing occurs just backwards as it should.
I took a quick look at the fault history on the other chiller which also been shut down for the winter but is still powered up. It has multiple incomming power type faults (generator exercise schedule ??) that I can post later. Thats as far as I got today, I plan on returning next week and megging the motor. Anyone else have any ideas on other possible issues to look for?

M# VSD351 KFT-46

[bobby m]

Maybe the other people damage the drive by incorrectly megging it.

[york56]

Go back into the fault history and look at the voltage and running data for the motor you can retrieve all the running data you will see a snap shot. You can go back numerous times. See if something doesn't look right , also I believe you can run that Chiller with the harmonic filter all unpluged.

[9675]

The biggest clue I can find in your story is GENERATOR test, you need to find out if this is done with machine running. If so this will cause major componet failure because it is not in sync with the sign wave that the scr were just seeing and this could cause a short or all kinds of crazy stuff. Start there and let us know.

[york56]

I also did find this SB on the trap filter which may explain why that is all burnt up.

[chillerguy81]

Thanks for the input men, I know I have some more detective work ahead of me next week. I will secure the drive so that I can at least power up the display and check the fault history. I have seen generators cause lots of damage to electronic equipment so thats one of the first things that came to mind. Any thoughts on the slighty higher voltage during the harmonic filter diode test?

[chillerguy81]

Thanks 56 I'll take a closer look at that. Here is mine :( 80882

[klove]

.04 (4/100ths) volts? Your meter ain't accurate enough to say that's a problem. The only CT's that are on the filter are downstream of the inductor - are you saying that the wires are burned all the way thru the inductor? As far as the generator thing, we run 'em all the time on gens and I don't recall ever having a problem. It's not unusual for the filter trap power resistors to burn and create problems. Get the new style that jci wants an arm and a leg for, and call Electronic Concepts about the small white capacitors (I just saw your pic - they were white at one time)mounted on the board. Best of all, just disable the thing and run it. They didn't have filters at all thru the TMII's and it never really created a problem. You can actually run around 30% distortion before stuff gets out of whack.

[chillerguy81]

Hi Klove thanks for the reply, I didn't think .04 vdc would warrant a problem but I guess I don't know exactly what that test is doing, just following directions :grin2: I'd be glad to listen if you could explain. Yes the filter trap wires are burnt up down to the plugs at the inductor CT's. Here's another pic, ain't camera phones great! 80902

[9675]

Ok now I saw the picture and then read first post again, I originaly thought you ment the filter power assembley, that what I get for reading to quickly, this could just be a failure or short of coponet of trap, looks like all that will need to new, sorry I couldn't help more.

[Randy S.]

Thanks for the info, York56.

I'll be servicing three of these in the next week or so.

[klove]

Hi Klove thanks for the reply, I didn't think .04 vdc would warrant a problem but I guess I don't know exactly what that test is doing, just following directions :grin2: I'd be glad to listen if you could explain. Yes the filter trap wires are burnt up down to the plugs at the inductor CT's. Here's another pic, ain't camera phones great! 80902

Sometimes, you just have to go with the flow of life. Unfortunately, that's the way component level testing is a lot of times on electronics. You don't always know why you're doing what you're doing, you just do it because that's the way the book says. In this particular case, you're simply seeing how much power it takes to trigger the diode to pass voltage (I don't know if that's a very good explanation - it certainly wouldn't impress a drive engineer), but you have to remember that you're not building a watch. Lot's of subjective stuff goes on in the bowels of these things.

I've found that more often than not, there's a certain amount of educated estimating in power electronics troubleshooting. A friend called me the other day and asked about a drive they were having problems with and they had narrowed it down to the drive logic or the microprocessor, and he wanted another opinion. I asked which one he thought it was. He said the microprocessor. I said change the logic. He said "why?". I said, it's always the other one or the one that costs the most when you have a choice of two :grin2:. Sort of like where it says in the checkout that if it's >5000 ohms then it's good, but if it's < 500 ohms it's shorted. What the heck is that supposed to mean???!!! :limb::gah: Where did the other 4500 ohms go?? Do they not matter??? :eek2::eek2: Sometimes, troubleshooting electronics is pretty easy, but more times than not, it'll just make you want to :bsing:.

[chillerguy81]

Thanks for the explaination Klove that helps. I like troubleshooting this kind of stuff, the only problem is this customer always wants everything quoted including diagnostics, how and the heck are you suppose to quote diagnostics. So I'm spending a little time on it during the maintenance and trying to get as much info as possible. Chances are it's just the trap assembly, we'll find out if .04 volts means anything when I throw the switch. :grin2:

[9675]

Hopefully the factory smoke will stay in for you!

[txhvac]

Thanks for the info, York56.

I'll be servicing three of these in the next week or so.

I'll second the thanks, I've gotten some good stuff from you. Much appreciated.

[mathias]

I had the same problem on a new chiller, the top of the contactor feeding the resistors - the right lug was very loose, u need an extention and open end wrench to get to it. Make sure power completely off and give capacitors time to bleed down. Go to lunch!

[chillerguy81]

Hopefully the factory smoke will stay in for you!

10-4 on that. Thanks to you all for your input, I'll keep you posted.

[Randy S.]

I looked at two today from that time frame that didn't have the filter.
Maybe a different drive, I dunno.

[york56]

The harmonic filter is an option either it is purchased when the machine is new or on a retrofit not all VSD's have them.

[chillerguy81]

Just wanted to give an update on this thread so you guys didn't think I wasn't sharing my findings. :grin2: I never did get a chance to dig into this further and find out whats wrong. As I said before this customer wants everything quoted and doesn't want to spend any money. Quoted the replacement of the filter trap and wiring that I knew was bad and didn't get the job. Thanks to everyone that had input and info to share.