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ST. CLOUD, Minn. - Listen to the cows. Your animals will let you know if there is a problem, if you watch them. That was the message that Stray Voltage Consultant Jerry Lush emphasized in his presentation, "New Developments in Stray Voltage," at Midwest Dairy Expo Nov. 28.
Stray voltage has been a major problem on dairy farms for many years. It's evidenced in many ways-cows that don't want to enter the parlor, are nervous while being milked, hold back milk, have reduced production, have increased mastitis, are reluctant to drink, and don't clean up their feed. Stray voltage causes stress that's reflected not only in reduced production but also in reproduction and animal health issues.
Stray voltage is defined as voltage that exists between two contact points, but is more properly defined as voltage between electrical neutral/grounding system and earth.
An alternating current (AC) with a stray voltage of 0.5 volts or more between the neutral and earth voltage is cause for concern and needs to be addressed. The reaction of animals to stray voltages varies with the amount of the voltage. Cows are more sensitive to small amounts of voltages than people, and will react to voltages that humans cannot feel.
Induced voltage is similar to static electricity but is always there, causing problems. It usually comes from a breakdown of wire insulation. It cannot be measured with a resistor, but is there, flowing through the cow. In stanchion or tie-stall barns, it may be reflected in animals that will not clean up feed from the concrete in front of them. Solutions include grounding the pipeline or stanchions, replacing wire, and/or putting wire in PVC conduit to protect it from physical damage.
Aging fluorescent light ballasts have been found to be another cause of stray voltage as they break down with age.
Using a farm near Ivanhoe, Minn. as an example, Lush pointed out problems when the grounding system is tied in to the rebar in the floor. In this example, water consumption was down, but no voltage was found at the fountains. The utility was disconnected and the farm ran on a generator for the weekend. Water consumption went up when on the generator.
"The only thing that changed was the current going into the rebar," Lush said.
He noted that an EMF meter wasn't sensitive enough to pick up the current but that he was able to find it with a Radio Shack Amplifier and microphone.
Electronic ballast lights as well as variable speed motors can cause harmonic voltage problems. Lush noted that LED lights, now on the market, cause no harmonic voltage problems, as they have no ballasts.
"They're expensive but will pay for themselves," Lush stated.[[In-content Ad]]

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