Oh well

[ptonsparky]

Last fall I started a series of threads on a local Dairy starting I think with information on RFI, electric fencers, a battery connected to earth with antenna for ground loop disruption, a rebar circle for the same thing, and utility pole grounds.

At the start we found 10 amps flowing on equip grounds, ground loops, etc. Owners purchased thousands of dollars of line filtering equipment which along with the battery & rebar circle were supposed to start improving things within days. No changes. We waited several weeks before starting the least glaring fixes to ensure a gap. With exception of total rewire we have done what we can do and have been given permission for. Went out to check on latest repairs and a PR call. I asked how things were going.

"Cell count is down, heifers are healthier, more cattle coming into heat, vast improvement in foot condition. Those filters must have worked" was the answer.

Hope they pay the last bill cause it is good one.

 

[brian john]

Did they try testing for neutral ground issues, multiple ground electodes on sub services, zero sequence testing at each sub panel?

 

[mdshunk]

Looks like I need to put some more serious effort into developing that zero sequence alarm that I had talked about a few months ago. It is dairy farmers who could really benefit from that. If they'll spend good money on hocus-pocus like battery operated rebar rings (?), then they ought to at least spend a couple shekels on something that is measuring something real.

 

[satcom]

Did they try testing for neutral ground issues, multiple ground electodes on sub services, zero sequence testing at each sub panel?

It the utility return path conductors sized for the present day usage, or is it like most of the countries older rural electric distribution systems way undersized, and the utilitiies are not about to spend the money to upgrade, until they are forced to.

 

[mdshunk]

It the utility return path conductors sized for the present day usage, or is it like most of the countries older rural electric distribution systems way undersized, and the utilitiies are not about to spend the money to upgrade, until they are forced to.

I'm not sure how the size of the serving conductors could ever present stray current problems for the dairyman.

 

[ptonsparky]

Multiple neutral bonds were corrected, EQ used as return corrected, faulted electronic speed control for fans removed from use, fan motors faulted disconnected, mv ballast neutral leads repaired so they were not using eg as return, pop cooler fan repaired, home made extension cord discarded, pole grounds repaired by POCO, underground feeder faulted to ground replaced, 4 wire feeders to subs replaced to include EG & isolate neutrals. Fencer grounding moved and new fencer installed.

Neutral load to POCO is very low and served by 240v hi leg delta of adequate size. 480v wye service has no neutral load. 208 derived from 480 problems were corrected. Low neutral current and viewed with Fluke 43B. Nothing that jumped out other than noticing how distorted the current draw of mv fixtures are.

Still multiple code violations and I have yet to talk them into allowing me to meg the branch circuits, motors, etc. Most faults were found with a 3v discontinued tester by Greenlee.

 

[Lxnxjxhx]

10 amps flowing on equip grounds

10 amps flowing on equip grounds

I'm having trouble imagining the current paths and the origins of this 10 A.
If you used a scope, is this current at 60 Hz? In any case, is it sinusoidal?

Can you post a simplified diagram of this setup?

It's hard for me to imagine an electric field in semiconductive soil that is high enough to harm cattle. I'd think it is not doing the people any good, either.

 

[iwire]

There is no question at all that stay currents in the earth effect cattle and milk production.

Four 'bare' hoofs, often standing in urine and feces covered soil etc.

Do some 'Googling' :smile:

The source is 60 hz and is often from open neutrals on the utility or customer side.

 

[mdshunk]

It's hard for me to imagine an electric field in semiconductive soil that is high enough to harm cattle. I'd think it is not doing the people any good, either.

That's okay. You don't need to imagine it. The effect on milk production is quite real and remarkable.

 

[satcom]

I'm not sure how the size of the serving conductors could ever present stray current problems for the dairyman.

Your not alone, we have a lot of utility engineers that can not grasp it or they do enderstand and refuse to step up to management.

Here in Jersey, we have large areas of utility distrubution with undersized return paths, some of the areas they can not use their swimming pools, or walk bare foot in their yards, poor pole line returns, and under rated sub station grounding, causes stray problems in wide areas.

The ground rods for poles are band aids the usually have little effect on supressing the problems, the real cures are expensive utility upgrades to an aging system.

The same is true of the building services, the service conductors are not the problem.

 

[ptonsparky]

I'm having trouble imagining the current paths and the origins of this 10 A.
If you used a scope, is this current at 60 Hz? In any case, is it sinusoidal?

Can you post a simplified diagram of this setup?

It's hard for me to imagine an electric field in semiconductive soil that is high enough to harm cattle. I'd think it is not doing the people any good, either.

The 10 amps was fairly easy. It was on the EG of a MWBC feeding some MV fixtures. A 2x the nm cable was stapled to had been broken and one of the staples shorted the EG to the Neutral. That and some problems with leads that had corroded off of the ballast(s) and shorted out to the metal case of the fixtures. By the time my help had spent a day in a bucket repairing fixtures and the cable that problem was gone. Some of it will be back again some day because it is nm cable in a dairy connected to fixtures that should not be there.

The electric field is hard for most of us to imagine and I haven't bought into it at all.