Quote Originally Posted by aelectricalman View Post
I have a customer that has come to me and said they are having major transformer overload due to harmonic distortion. We are seeing about 11% Vthd. They have some equipment where they have drilled through the concrete floor and drove a separate ground for the new peice of equipment. They have grounding issue and are tripping and burning up drives like NASCAR tires. This is a large primary user.

There are many ways to skin this cat. I understand a power quality study should be the first approach in providing a direction. Once this is done, what type of grounding studies are out there that we could have performed to help determine if there are ground loops, high Vthd, high Ithd. I am looking at some line reactors as well but i don't want to get the cart in front of the horse.

Thanks for your help, all.
In my opinion, I should first check and correct the grounding system of the customer then measure the %Vthd after the correction. I think there was an issue on the customer's equipment where they drove a separate ground rod for their "isolated ground" I presume, this may create a "ground loop" or potential difference between the electrical system and the equipment.