Harmonics and dairy cattle

[stray spark]

Help! I am having some problems with harmonics in Wisconsin and am at wits end on where to turn. If I remember my harmonics from aprenticeship class 15 years ago, harmonics cause heat and do not travel far from their source. Do any of you have any experience with the mitigation of harmonics in relation to a dairy? We were using a 1 to 1 ISO transformer on a 480 system to isolate the drives from the rest of the system. Now we are being told to get rid of the transformers and go to special filters from Canada. The company is displaying data of 262 to 2198 mv of harmonic current, but at all different frequencies. any books or hints etc would be greatly appreciated. p.s. The facility has been inspected by 2 state inspectors, the psc, and 2 independent stray voltage "experts" and all give it a thumbs up. Utility says there is no "stray voltage" but both independents and my Fluke 434 say different. Thanks in advance!:-?

 

[Rockyd]

Good place to start

Click here

 

[ptonsparky]

Are the animals or production suffering from these harmonics?

 

[stray spark]

Suffering in Wi

Suffering in Wi

Are the animals or production suffering from these harmonics?

Yes, cell count went from 114 thousand to 340 thousand, water intake dropped, huge impact on immune system. Once they get sick, they are DONE. I just don't buy that it is harmonic related, but I also am not real educated on the effects of harmonics. Not much for RELIABLE research out there. Seems like everybody who seems to know something wants to sell something instead of fixing the problem. Also hearing a lot of talk about voltage injection systems that inject voltage 180 degrees out of phase to cancel out any stray voltage on the grounding system. Any one ever had any experience with these? Any tidbit of info would be greatly appreciated. I am too young to go bald from pulling my hair out and will look real dumb with a flat face from banging my head against a brick wall.

 

[Bob NH]

Help! . . . We were using a 1 to 1 ISO transformer on a 480 system to isolate the drives from the rest of the system. Now we are being told to get rid of the transformers and go to special filters from Canada. The company is displaying data of 262 to 2198 mv of harmonic current, but at all different frequencies. The facility has been inspected by 2 state inspectors, the psc, and 2 independent stray voltage "experts" and all give it a thumbs up. Utility says there is no "stray voltage" but both independents and my Fluke 434 say different.

Is there any chance that "the company" measuring 2.2 Volts of harmonics (sounds pretty small compared to 480 Volts) is the company trying to sell the special filters from Canada?

What is the rationale for concluding that a wide range of experts don't know what they are talking about?

Harmonics travel on wires just like the current from the 480 Volt system. Why is it necessary to "migtigate" the harmonics? If you can't measure real voltages in places that the cattle will be touching, what is the problem?

 

[mhulbert]

This sounds like stray voltage issues, not harmonics! If the harmonics are getting to the cows, then the fundamental 480V sine wave is going to get to them too! In other words, the wire insulation will stop a harmonic current/voltage just the same as it will stop your 60Hz voltage. This sounds like a stray or touch voltage type of problem, where minute amounts of current are flowing through the animals because of different voltage levels on the ground/equipment/building steel, etc.

Have you checked the motors that are on VFD's? Perhaps they are not invertor duty and the insulation is breaking down, leaking current to their chassis and thus the piping--->animals?

Good luck with this one!

 

[ptonsparky]

I don't believe it matters to the cattle whether the voltage applied is DC or 480 hz and without going back and studying this all over again, I think .4 volt starts to be a problem. I know your dairy is different than the ones I worked on years ago, but I actually had a galvanized water tank sitting in manure that created over .5 volt dc measured both with on an old analog Simpson meter and a digital that could tell the difference. Moved tank, DC volts dropped to zero and cattle settled down. I am bald but I use to beat the back side of my head against a pole to save my face. Good luck.

 

[George Stolz]

I agree, I don't see the correlation between harmonics and stray voltage, but harmonics are not my strong suit.

Not to say my stray voltage knowledge is my strong suit, but...

When you do the testing, where and what exactly are you testing? From what I've heard, tracking down stray voltage is a tedious, recording data event.

Is there a stock tank or something along those lines that shows a voltage to the earth around it? Is there a specific lot that are more effected by the voltage, or is it the whole herd? If there is a piece of equipment on the premises showing a voltage, does the voltage stop when the motors are disconnected?

 

[allenwayne]

Oh just turn up the voltage and stop when they are medium rare. I hate well done beef YUCK

 

[brian john]

1. Why do you feel the harmonics are harming the cattle?
2. Have you tested for current and voltage THD and all levels of harmonics with a disturbance analyzer?
3. Have you check for neutral to ground voltage, stray current and or neutral grounds downstream from the service.
4. Is the equipment properly installed, not just per the manufacture specs, (I have seen equipment installed in a non-NEC compliant manner per manufactures specifications.
5. As mentioned is the specifier a salesman? Often the case. The number of times I have heard sales engineers push their product over what is necessary, too many to count.

 

[stray spark]

Stray and well done.

Stray and well done.

I have to wait until Sunday night to post the data from all the tests as it is all on site. Needless to say I never thought in one day I would have this many intelligent responses. and I loved the one about turning up the voltage. Nothing better than med. rare beef and cottage cheese. And I never thought of hitting the back of my head so it would not hurt my face. Just goes to show even when you are so frustrated you could scream, A group of your peers can make you think about things different and laugh. Thank you all. It is nice to finally find a place that has both humor and intelligent people. :smile:

 

[ptonsparky]

I watched/assisted two guys (engineers) from the University of Nebraska do a check for stray voltage in the 80s. They came with a whole van of equipment that didn't even come close to the Fluke meter you are using. The trick is going to be deciphering what it tells you.

 

[JohnJ0906]

Do you have an equipotential plane in place? (547.10)

 

[ramsy]

Searching for the word equipotential using google's advanced search with mikeholt.com defined as the URL shows prior comments on this topic, including discussions of how to eliminate the service (charged earth or neutral) as the source of livestock agitation on a dairy or farm.

The service is a usual suspect for a charged earth (stray voltage), but I don't remember VSD's being included in those discussions. DC drives produce high frequencies, increased motor-circuit reactance, & sometimes leak to earth, AKA "fluting".

Your Fluke 434 might be able to compare frequencies between these motor casings to motor shaft, or casing to neutral, against the locations where earth is charged (leaking) 2vac. If your 434 can pick up the noise or show identical distortion / frequency signatures then you may have one of those rare VSD drive bearings that is fluting, shaft-to-earth.

If the leak is not related to noise / harmonics at all, your fluke should still pick up any distortion in the fundamental signature @ 60Hz, which can also be compared against different pieces of equipment you may suspect leaking to earth.

 

[ramsy]

For checking out the service, please see georgestolz excellent stray voltage diagrams in the NEC forum, "stray voltage" thread, by jinglis; beginning with post #7.

George superbly illustrates how high-impedance neutrals and bootleg grounds can charge the earth between distant xfmrs and structures or equipment.

The less reliable URL below may be invalid in a few days.
http://www.mikeholt.com/code_forum/showthread.php?t=82041

 

[ptonsparky]

For checking out the service, please see georgestolz excellent stray voltage diagrams in the NEC forum, "stray voltage" thread, by jinglis; beginning with post #7.

George superbly illustrates how high-impedance neutrals and bootleg grounds can charge the earth between distant xfmrs and structures or equipment.

The less reliable URL below may be invalid in a few days.
http://www.mikeholt.com/code_forum/showthread.php?t=82041

iwire has a post on this same thread about using listed low impedance meters to eliminate the possiblity of phantom voltages.

Back in '06 we used a 500 ohm resistor in parallel wtih the meter leads, but I also knew electricians, now dead, that used their fingers to check for voltage across 220v receptacles.

 

[don_resqcapt19]

The biggest source of the stray voltage is the voltage drop on the utility primary grounded conductor. This conductor is bonded to earth at least 4 times per mile as well as at each transformer where it it connected to the secondary grounded conductor. This places the earth in parallel with both the primary and secondary grounded conductors and will often result in stray voltage problems. These problems are most often noticed at dairy farms and pools where the low level voltage causes problems.
Don

 

[ptonsparky]

The biggest source of the stray voltage is the voltage drop on the utility primary grounded conductor. This conductor is bonded to earth at least 4 times per mile as well as at each transformer where it it connected to the secondary grounded conductor. This places the earth in parallel with both the primary and secondary grounded conductors and will often result in stray voltage problems. These problems are most often noticed at dairy farms and pools where the low level voltage causes problems.
Don

This also means that your neighbors problem is now yours. The problems your customer is experiencing may vary well originate the next farm or two away.

 

[George Stolz]

The biggest source of the stray voltage is the voltage drop on the utility primary grounded conductor.

Don, can you elaborate? Is it due to the already high voltage of the primary, or ... I'm all out of guesses.

Is it just due to the extensive earthing of the primary? If so, what aspect?

Ramsy, thanks for the kind word, I just bluff well and doodle worse.

 

[don_resqcapt19]

George,

Is it just due to the extensive earthing of the primary? If so, what aspect?

The primary neutral has current flow and therefore has voltage drop. Remember that even a 1% drop can be a lot of voltage at the primary level. The earth is in parallel with the primary neutral. The current flows through the earth in an unknown path. If you are remote from this path, and you measure from the electrical system grounding system to this remote earth you are measuring the voltage drop on that primay conductor.
Don