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Faunsdale, AL | In the link to dairyland isolators, one of the on-farm causes mentioned was unbalanced 120 volt loads. That can be hard to totally eliminate as different things are turned on and off around the farm, but some time spent in the breaker box with a clip-on ammeter can be very rewarding. You would want to do this during milking as well as between milkings etc and record the amperage on the lines coming into the panel When you find a big difference between the amp load on a phase/line, the solution can be as simple as moving a single phase breaker from one space to the one above it or below it which moves a circuit from one line to the other. Do note that there are 3 phase services with a "power leg" that is NOT USABLE for 120 volts, so plugging a 120 volt breaker onto that "every third space" down the 3 phase panel will result in the circuit getting about 200 volts instead of 120. Some electricians and codes split all the single phase off into a separate panel from these type 3 phase services, so this isn't a problem unless someone comes along later and adds 120 volt circuits into the 3 phase panel.
Back in the days of parlor feeders, we had a set of Clay electric trickle feeders. A small 120 volt electric motor about as big as a clock would switch on a certain % of a minute etc and dribble grain into the feeder. We discovered that every time these switched on, there was a voltage surge between feeder and grates the cows stood on. Once I measured it and knew it was in the range of 3-5 volts, I could take a damp finger if there were enough scratches on it or touch two wires to the tip of my tongue and feel the similar buzz that you get when we used to touch a "dead" 9 Volt transistor battery to our tongue on a dare.
The solution to the feeder problem was to break the feeders into halves so 1/2 fed from one line and the second 1/2 fed from the other line. Since they alway came on at the same time, the load was balanced and the stray voltage was eliminated.
I have also heard of the same happening every time the milk pump clicked on.
It helps if as much of the equipment in the parlor as possible is 3 phase or 240 volt vs 120 volt so it doesn't use a neutral connection at all.
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Stray Voltage
