Ground Fault detection

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
We’ve been doing work at a Dairy for quite a few years. This week I get a call that they had to pull thirty cows because of mastitis in one day. Usually one a month. The manager immediately thinks of stray voltage. I reminded him of the lack of EGs to three of the buildings. ‘Yes, you keep telling me that.’ Ok.

I send the guys up to make sure we don’t have a fault in the barns that hasn’t burned itself clear or tripped a breaker yet.

Not electrical. Turns out it was a two stage medication that was not triggering properly. The vendor responsible lost that contract immediately.

I think I finally got him to understand he needs the EGs.

There is not an overnight fix so in between I’m thinking of GF detection. We use a flex loop current imbalance as it is now with meters to trouble shoot. Do they make similar for semi permanent installations?
 

FionaZuppa

Senior Member
Location
AZ
Stray voltage, like bird on a wire, or stray current?

If there were a uncleared fault and all the return current was passing through the floor that they stand on, this affects them how?
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
Stray voltage, like bird on a wire, or stray current?

If there were a uncleared fault and all the return current was passing through the floor that they stand on, this affects them how?
Stray voltage is the common term
Current would be correct.
Affects milk production, fertility, general health. They feel the voltage difference front to rear hooves.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Engineer
I used to use some from a company called NK Technologies, they are sold through many vendors like Automation Direct.
 

Cow

Senior Member
Location
Eastern Oregon
No EGC's with the feeders? Are the neutrals bonded at the separate buildings with proper grounding electrodes? Do you have other metallic paths back to the service?
 

jusme123

Senior Member
Location
NY
Don’t the barns/ milking area/feeding area require an equipotential ground grid or something similar for the livestock?
 

GoldDigger

Moderator
Staff member
Don’t the barns/ milking area/feeding area require an equipotential ground grid or something similar for the livestock?
Yes. And with some attention to a smooth potential gradient where, for example, a ramp enters the building. No matter how far you extend the equipotential grid, you can still have step potentials at the boundaries unless you take precautions. Especially where there are significant ground potentials from inadequate POCO MGNs.
 

jusme123

Senior Member
Location
NY
Yes. And with some attention to a smooth potential gradient where, for example, a ramp enters the building. No matter how far you extend the equipotential grid, you can still have step potentials at the boundaries unless you take precautions. Especially where there are significant ground potentials from inadequate POCO MGNs.
Kinda makes sense to have, never realized it effects the milking til Pton mentioned it
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
The barns are 20 to thirty years old.
The Grid would be great, but I do not believe it is intended to replace an EG.

No EGC's with the feeders? Are the neutrals bonded at the separate buildings with proper grounding electrodes? Do you have other metallic paths back to the service?
480/277 at service Plus a step down for single phase for milking office area. All done properly for the time. AFAIK.
No EGCs with the buried feeders. Electrodes were used in lieu of EG at load end of feeders.
No 277 neutral load any where. (A good thing.)480/277 at service Plus a step down for single phase.
Small transformers installed in far areas for 120v, may or may not be floating.
Some buildings are wood frame with sheet metal siding, some steel.
Siding and typical gates at end of barns to common alley would be the only other metallic paths I am aware of. There is rotting EMT strung throughout the buildings.
 

Cow

Senior Member
Location
Eastern Oregon
The barns are 20 to thirty years old.
The Grid would be great, but I do not believe it is intended to replace an EG.



480/277 at service Plus a step down for single phase for milking office area. All done properly for the time. AFAIK.
No EGCs with the buried feeders. Electrodes were used in lieu of EG at load end of feeders.
No 277 neutral load any where. (A good thing.)480/277 at service Plus a step down for single phase.
Small transformers installed in far areas for 120v, may or may not be floating.
Some buildings are wood frame with sheet metal siding, some steel.
Siding and typical gates at end of barns to common alley would be the only other metallic paths I am aware of. There is rotting EMT strung throughout the buildings.
Recently, one of our good feedlot customers purchased a house that came with a small half circle, irrigation pivot and pump, etc.

He asked me to look it over. I noticed someone ran a 3 wire 480v feeder out to the pumphouse/pivot, and tapped everything off of it. No egc.

I gave him a price to replace the feeder with a 4 wire cablecon and address the grounding to the additional electrical equipment.

I would do nothing less than that in your instance as well. Replace it all. Or dig it up and lay an EGC next to the other wires.

As soon as you attempt to add a gf detector/relay, they'll never fix it properly.

Let me ask you this, if a couple cows die from a ground fault or a few drop in milk production, and the dairy manager goes back to the old standby "stray voltage" whether he's right or not, will he be looking at you and your ground fault relay as something that should have prevented that?
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
Recently, one of our good feedlot customers purchased a house that came with a small half circle, irrigation pivot and pump, etc.

He asked me to look it over. I noticed someone ran a 3 wire 480v feeder out to the pumphouse/pivot, and tapped everything off of it. No egc.

I gave him a price to replace the feeder with a 4 wire cablecon and address the grounding to the additional electrical equipment.

I would do nothing less than that in your instance as well. Replace it all. Or dig it up and lay an EGC next to the other wires.

As soon as you attempt to add a gf detector/relay, they'll never fix it properly.

Let me ask you this, if a couple cows die from a ground fault or a few drop in milk production, and the dairy manager goes back to the old standby "stray voltage" whether he's right or not, will he be looking at you and your ground fault relay as something that should have prevented that?
No, he is wanting a price so they can get some planning done. They are not dumping milk, but are losing money at every milking. Month to month means + or - cash flow. We did a complete rewire on one barn last year.

The relay is my thought that maybe we can be warned at the start of a fault. Short or long term. IDK how or if it will work out. I may put one together as an experiment. They do not appear to have a problem at the moment with stray current/voltage.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
480/277 at service Plus a step down for single phase for milking office area. All done properly for the time. AFAIK.
No EGCs with the buried feeders. Electrodes were used in lieu of EG at load end of feeders.
No 277 neutral load any where. (A good thing.)
So if the 480/277 feeder neutral conductor is not connected to any loads but it's bonded to the panel at the end of the feeder, it appears that electrically it would behave just like an EGC because there would be no load current through it to induce a voltage drop. Is this line of thought consistent with how the installation is configured?
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
So if the 480/277 feeder neutral conductor is not connected to any loads but it's bonded to the panel at the end of the feeder, it appears that electrically it would behave just like an EGC because there would be no load current through it to induce a voltage drop. Is this line of thought consistent with how the installation is configured?
The neutral is bonded at the SE.
There are no feeder neutrals. There are no feeder EGs. Three phases to the barns.
 

FionaZuppa

Senior Member
Location
AZ
Stray voltage is the common term
Current would be correct.
Affects milk production, fertility, general health. They feel the voltage difference front to rear hooves.
But how does a little stray current under their feed affect their milk production? Magnetic field sensitive ?
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
But how does a little stray current under their feed affect their milk production? Magnetic field sensitive ?
...feet...
They are very sensitive to voltage, hoof to hoof, mouth to hoof. If they don’t eat or drink, milk production goes down. Voltage in the milking process may cause them to not milk out and results in mastitis. That needs to be treated while the cow is removed from production and worse case, sent to slaughter.

Equipotential bonding grids, bird on the wire, is one way to alleviate the problem but these barns are old enough I doubt they have them. No or limited line to neutral loads is another.
 
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