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Variable Speed Drives And Stray Voltages In Dairy Farm


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There is a lot of fog and theories about Variable speed drives creating stray voltages and causing problems to cows in dairy farms.


I know cows are sensitive to stray voltage, but do VSd's cause such voltages ?.


What are the methods to avoid/measure these voltages?


Any thoughts/ideas are appreciated.

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Hi chaterpilar


This a definite fact and the problem can be minimized by the correct installation of the correct VFD.


The VFD generates a high voltage high frequency carrier on its output terminals. This is connected to the motor and the high frequency currents can leak in all directions.


There are a number of steps that can be taken to minimize the problem, but the first is to ensure that you start with a good drive that is easily able to comply with the European EMC requirements. Some of the cheaper VFDs just can not be quietened down sufficiently.


I have a page on installing VFDs in irrigation installations for minimum EMC and these steps are exactly the same in cowshed applications. see http://www.lmphotonics.com/vsd/vsd_05.htm


If you have any further questions, ask them here.


Best regards,

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