| WELCOME TO THE WORLD OF STRAY VOLTAGE!
We sincerely hope these pages will help you in your dairy operation. We will try to give you an overview of our experience with stray voltage and how it has adversley affected so many dairy operations. We do not have all the answers by any means, but we have found some things that work.
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Stray voltage can come from on-farm or off-farm sources. Faulty dairy equipment is one example of a possible on-farm source. The electric utility system is an example of an off-farm source.
Stray voltage testing is best done using an oscilloscope. These instruments display not only the numerical value of the voltage, but also a picture of the waveform that can be used like a fingerprint to help determine the source if stray voltage is found. Each piece of electrical and dairy equipment should be operated during such testing, and the results can be saved to a computer disk. Some of the highly specialized oscilloscopes are battery powered and have on-board recording capabilities as well.
Many of todays motors and other electrical equipment are designed to be energy efficient. To achieve this, control systems are employed such as variable speed drives and electronic switching power supplies. These can be a significant source of stray voltage because of the high amount of harmonic energy they can introduce into the farm grounding system. An oscilloscope is always required to evaluate this problem.
Advanced testing can analyze such things as milker pulsation and vacuum at the claw, as well as electrically clean operation of power supplies for consistant circuit board performance.
Other more obscure equipment such as well pumps and underground cables, are properly tested using insulation leakage testers capable of appying high DC voltages. These instruments are known as Megohmeters.
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