The cream in your morning coffee relies on a stable grounding grid.
Most dairy milking parlors or carousels today are highly computerized and require many different electrical devices to operate. Farms are usually in areas where there is open country and/or acreages with large metal buildings. Concrete, metal, and stainless steel, combined with humid milking conditions, will create conditions that can make it difficult to keep the ground grid stabilized.
Cows eat from automatically fed stainless steel stalls that are computerized and give each bar-coded cow exactly the correct feed combination. While being milked, the cow is treated to their special meal, then washed, rubbed, and cleaned. Cow’s mouths are extremely sensitive, and stray voltages can come through the feeder, shocking them. They then stop eating and the milk production is reduced.
On a Wye connected electrical system, grounding stability is a challenge. In perfect conditions, most farms do not run into problems. The typical application to use on milking farms or pig farms is the neutral isolator transformer. It is a 1:1 turns ratio transformer installed onto a service feed neutral conductor. It separates the physical ground with a transformed connection. On the secondary side there are fused terminals, and they need to be measured and checked. If contamination is an issue or if lighting or GFI failures occur, these isolators can quit.
Circuitry balancing, grounding theft and other industrial influences can cause stray voltage rises. Ultra-high voltage corridors, large water or gas lines with cathodic protection or faulty pumps can create complicated problems. I also had a case where rail lines were being induced, creating issues on a neutral system.
I had the privilege to work with one of the best specialists in the world in dealing with stray voltages. He and I would use many different specially designed ground metering devices and sleuth out the design issues. Proof of situational losses due to stray voltages often will only appear after investigation or in situ testing. This is worth the effort as the utility company needs to protect itself from potential lawsuits, as many farmers around the world have had large claims. The agriculture industry deserves to be compensated for its’ loss of milk production, so finding a solution to the cow’s moo-ving experiences is paramount.
Grounding on Delta and Wye overhead systems is complicated, just like phase balancing, circuitry revenue losses and power quality. Especially today, with more electronic loads and controls that are operating together.
The cows are fortunate they do not live in the cities!
Keeping them safe is very high on our list — Linemen can always appreciate a nice glass of milk with homemade cookies at the end of a shift!
Bruce Masse _ Trouble Technician