# Plant Problems



## Cletis (Aug 20, 2010)

I was called to look at some problems of a local plant. They have a large number of VFD's btw. They are having your typical burning up of neutrals, short life spans of transformers, computer problems and so on. They had a power quality analysis already. Not sure of results. They mentioned they had some bad 3rd, 9th, and 15th harmonics as well. There local maintainance guy says they need to drive some ground rods in at large motors and see what happens after that ? huh? Anyhow, I think we are going to have to come up with a VFD mitagation plan. I plan on starting with each VFD supplier and go one by one until the power quality analysis starts to straighten up. We may run some new neutrals right after some os this and replace a few transformers as well. Any other tips would be greatly appreciated on a total harmonic reduction plan.


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## user4818 (Jan 15, 2009)

Nobody believes you.


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## Nick0danger (Aug 19, 2012)

Harmonic filter? Why do they not have an engineer involed it being a plant?


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## Cletis (Aug 20, 2010)

*?*



Peter D said:


> Nobody believes you.


So what would your plan of action be mr. master electrician...quick. No answer=you don't know


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## MHElectric (Oct 14, 2011)

Dang Cletus, how do you go from hustling 200 amp upgrades at old ladies houses to high end industrial establishment troubleshooting? 

Heck I dont even know what triplen harmonics do. Id say call a pro.


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## user4818 (Jan 15, 2009)

*answer*

I bet that your hot dogs are taking too long to cook in the microwave, aren't they? Tie the microwave into the stove circuit. The stove circuit is 240 volts. That is what you need to operate your microwave correctly. Talk to one of the home improvement experts at your local home depot or Lowes. They can explain how to do this and provide you with all of the materials required to complete the project.


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## Cletis (Aug 20, 2010)

*yep*



Peter D said:


> I bet that your hot dogs are taking too long to cook in the microwave, aren't they? Tie the microwave into the stove circuit. The stove circuit is 240 volts. That is what you need to operate your microwave correctly. Talk to one of the home improvement experts at your local home depot or Lowes. They can explain how to do this and provide you with all of the materials required to complete the project.


Just as I expected...your not really an electrician are you ? :thumbup:


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## user4818 (Jan 15, 2009)

Cletis said:


> Just as I expected...your not really an electrician are you ? :thumbup:


If I'm not an electrician, does that mean you're not one either, since we're the same person?


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## Cletis (Aug 20, 2010)

*PF*

Anyhow, I am thinking about using passive filters and 6 pulse AC drives to start. seems to be the most effective solution from my current state of knowledge on the subject


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## BBQ (Nov 16, 2010)

Cletis said:


> Anyhow, I am thinking about using passive filters and 6 pulse AC drives to start. seems to be the most effective solution from my current state of knowledge on the subject


I am thinking you should pop open another Pabst Blue Ribbon and relax in your hot tub


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## MDShunk (Jan 7, 2007)

Cletis said:


> I was called to look at some problems of a local plant.


Sure you did.

Your post reads like the introduction to a bizarro world line reactor case study.


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## JRaef (Mar 23, 2009)

I'm so confused as to whether or not "Cletis" is a real person or an insider joke that I'm not in on, I feel reluctant to respond. But here goes anyway, just in case...

Given the scenario you describe, you are not 100% sure where the harmonics are coming from exactly (other than "the VFDs"), so your course of action needs to address the system as a whole unless proved otherwise. You can therefore go two ways from there: investigate it to the nth degree, or address it as a single system, which is likely where you will end up anyway. If you chose to address it as a single system, then you have a few choices, one of which you have already mentioned: passive filters on each and every VFD. That will likely work, but will be very expensive. A more reasonable alternative, in my recent experience, is to go with what's called an Active Harmonic Filter, connected as close to the Point of Common Coupling (PCC) as possible. I've been using the TCI H5 series AHF units lately, they have been fantastic. The big advantage to doing it this way is that they correct what you have now and what you add later (provided they are sized for future expansion). Plus, they don't over correct because they MEASURE the harmonic content and only react to the problem. So far every installation I have done with these has been a rousing success as far as harmonic mitigation goes, meeting or exceeding the IEEE 519 guidelines.

And no, I don't work for them, in fact my company brand-labels MTE reactors instead of TCI so there is a little bit of conflict for me there. But I had seen the TCI H5 filters work before I stared using them and once I see a success, I stick with it. The MTE Active Filter may be fine, I've just not experienced one in action yet. I know that there is another big brand out there called Acusine or something like that, I have never seen one in action but heard a few complaints about them.


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## etb (Sep 8, 2010)

whoops double post


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## etb (Sep 8, 2010)

Cletis, do you know what is special about 3 9 15? There are simple solutions......



JRaef said:


> A more reasonable alternative, in my recent experience, is to go with what's called an Active Harmonic Filter, connected as close to the Point of Common Coupling (PCC) as possible. I've been using the TCI H5 series AHF units lately, they have been fantastic. The big advantage to doing it this way is that they correct what you have now and what you add later (provided they are sized for future expansion). Plus, they don't over correct because they MEASURE the harmonic content and only react to the problem. So far every installation I have done with these has been a rousing success as far as harmonic mitigation goes, meeting or exceeding the IEEE 519 guidelines.


I think active filters are going to be the future. Industry stepped up to PFC power supplies for PCs and servers, and that was a great step. From what I've seen of the electronics side of several European countries (mostly I read about UK & Germany) their equipment must meet harmonic standards. I don't know what standards must be met in the states, but as far as I understand there are only recommendations. Anyway my point is that the European way of correcting harmonics at each load makes more sense.....you take harmonics out of the building electrical design, for the most part. Of course there's a difference between industrial and non-industrial world..... I digress, but it's the same ole, plug the hole in the boat instead of relying on the bilge pump..........


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## denny3992 (Jul 12, 2010)

3 
9 
15


the dates of the month cletis' dogs are ovulating


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## Del (Feb 10, 2011)

In the UK, with any addition of a VFD over 7.5Kw, a power study has to be done, and the mitigation of the Total Harmonic Disturbance has to be included with the VFD design, precisely to avoid the issues Cletus talks about in the intro post.
I would hazard a guess, there are no output or input filters on the VFD's, coupled with using non shielded cable on long runs, and add in a high ground fault resistance.
First thing is to address the cables, and filters.
Note shielded VFD cable also nees to have an exterior grounding conductor as the functional ground.
Second get the ground tested.
This is where Fluke are missing a trick in not letting north american contractors have a crack at the installation testers (Fluke 1651/2/3 series).
We had similar problems on a plant, I brought out my 1651(imported personally from UK)and found the sparkys had not connected the Xo point to ground, via a 347V single phase to ground loop test.
This will be a money maker for Cletus.


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## Peewee0413 (Oct 18, 2012)

Cletis said:


> I was called to look at some problems of a local plant. They have a large number of VFD's btw. They are having your typical burning up of neutrals, short life spans of transformers, computer problems and so on. They had a power quality analysis already. Not sure of results. They mentioned they had some bad 3rd, 9th, and 15th harmonics as well. There local maintainance guy says they need to drive some ground rods in at large motors and see what happens after that ? huh? Anyhow, I think we are going to have to come up with a VFD mitagation plan. I plan on starting with each VFD supplier and go one by one until the power quality analysis starts to straighten up. We may run some new neutrals right after some os this and replace a few transformers as well. Any other tips would be greatly appreciated on a total harmonic reduction plan.


Running new neutrals might be smart. Or possibly try and find loose or disconnected xo's


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## albert (Mar 17, 2011)

Del said:


> In the UK, with any addition of a VFD over 7.5Kw, a power study has to be done, and the mitigation of the Total Harmonic Disturbance has to be included with the VFD design, precisely to avoid the issues Cletus talks about in the intro post.
> I would hazard a guess, there are no output or input filters on the VFD's, coupled with using non shielded cable on long runs, and add in a high ground fault resistance.
> First thing is to address the cables, and filters.
> Note shielded VFD cable also nees to have an exterior grounding conductor as the functional ground.
> ...


 
Isn't the 1653 meter only rated for 500VAC for CAT III? Unless I am misinformed you could potentially use it on a 480 or 600 volt system and get hurt.


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## D-Bo (Apr 15, 2012)

Cletis said:


> I was called to look at some problems of a local plant. They have a large number of VFD's btw. They are having your typical burning up of neutrals, short life spans of transformers, computer problems and so on. They had a power quality analysis already. Not sure of results. They mentioned they had some bad 3rd, 9th, and 15th harmonics as well. There local maintainance guy says they need to drive some ground rods in at large motors and see what happens after that ? huh? Anyhow, I think we are going to have to come up with a VFD mitagation plan. I plan on starting with each VFD supplier and go one by one until the power quality analysis starts to straighten up. We may run some new neutrals right after some os this and replace a few transformers as well. Any other tips would be greatly appreciated on a total harmonic reduction plan.


It sounds like you just Google these obscure electrical scenarios and then regurgitate it back to us as a real life situation to make yourself sound credible. If I'm wrong I'm sorry


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## SparkyBrodie (Oct 31, 2012)

Ground Potential rise may have a issue with the premature failed equipment. Meaning voltage from a ground strike can be induced on you grounding system and back feed your electrical system. I have seen it before in a similar situation with equipment failing prematurely. I would stay away from driving ground rods for each piece of equipment as this will cause a difference of potential at each ground rod and piece of equipment. 

my 2cents


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## Peewee0413 (Oct 18, 2012)

There is actully more to GPR. Did u google that? Also it really is no concerned to the normal operations. To have problems you would need very high potential to travel large distances and mess things up. Chances are grounding anything with a ground rod wont hurt anything. Also if you don't have grounding problems with the device, it wont help it neither lol. Burning neutrals and destroying.g transformers? Is the transformer correct for the application? I think that's your problem


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## SparkyBrodie (Oct 31, 2012)

I was summing up what GPR rise is and no I didn't google anything but you may if you like. I don't take chances I like to give solutions. So if this is a chest puffing match you can win, Im just trying to help. and yes adding additional ground rods if they are not all connected will cause problems because there will be different paths to ground and not all of the same resistance. And last I consider a lightning strike a very high potential.....actually thats about as much potential you are going to get so google that...


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## Peewee0413 (Oct 18, 2012)

Lightning is high frequency, it cant travel through plant ground system long distances, sparky! "Puff,Puff" XL=2 pi*F*L. Im just messing with you. Nobody in this forum are geniuses or we wouldn't be in here talking. Its more fun to mess around with weird answers than to even read the problem up top


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## Peewee0413 (Oct 18, 2012)

I don't find the reason behind this question. I tell u what its either power problem. Wiring problem. Or a crappy VFD other than that its just electricity bro.( if you can't branch power, wiring down to find the problem ..go wire up houses). The only problems I can't always find out myself involves parameter settings on instruments, which sometimes is still easy.


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