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Emc Levels In Dairy Sheds


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I have been asked to hep to sort a problem in a dairy shed where cows are milked.

It is common practice today, to use VFDs to control milk pumps, vacuum pumps, backing gates and the turntable.


One of the problems with using VFDs, is that there is always a level of conducted emissions that get into the earth system and appear as stray voltages.

A cow is many times more sensitive to these stray voltages than a human and it is not uncommon to see problems in the milking shed due to the irritation caused by these stray voltages.

After considerable investigation, I have not been able to come up with an acceptable stray voltage amplitude that can applied to the dairy shed.

Does anyone have an authoritive reference that gives threshold voltages that should be applied around cows?

Also, has anyone come across specific testing methods for conducted stray voltages in dairy sheds?


Reducing the emissions is not a major issue, I can give simple instructions for this, but I need a reference to show that the remedial action needs to be taken.


Best regards,


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