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Is there a minimum separation established between a Data Center and a 115KV Substation. There is a concern about the EMI to the servers, routers, etc. The Ground Potential Rise in a Data Center adjacent to a 115KV Substation is 809V, is that ok or too high?

Hi Hugo, Ben, Bhimesh,

Thank you for your question regarding Ground Potential Rise (GPR) on a data center, it is our pleasure to help.

Data Center’s are big energy consumers, and as such they often have substations and generators located nearby.  The Ground Potential Rise that can form during the normal operation of these systems, and which will get dramatically worse should one of them fault, is certainly something to be concerned about.  The GPR is used to determine various engineering factors, the most important of which are the Step & Touch Voltage hazard.  These voltages can cause serious injury or even death to personnel and can destroy equipment. 

When someone says that their GPR is 809 volts, what they are saying is that the maximum voltage at any one point within their facility is 809 volts.  This also means that there is a minimum voltage and thus a difference between the two voltages which is called Ground Potential Difference or GPD.  Consider that the corner of the data center that is closest to the high-voltage substation will see the greatest voltage, and the corner furthest away will see the least.  This difference in potential from one corner to the next, can often be several hundred volts.

Why can a bird land on a high-voltage wire without being electrocuted?  Because there is no difference in potential that could cause current to flow.  The same is true for your data center.  As long as the difference in potential (GPD) is low enough, your data canter can easily handle a 809 volt GPR (or even greater).  What your real concern should be is the difference in potential (GPD) within your data center.  A 200 volt difference in potential from one side of your data center to the other side, will allow a lot of current to flow which can damage sensitive electronics and possible injure or kill personnel.

Rest assured, it is quite normal to see data centers located adjacent to substations, and to see GPR values far greater than 809 volts.  It’s just that the greater the GPR, the lower the GPD needs to be to mitigate the effects.  A properly designed grounding system will be able to protect your data center and the personnel that work in it.

Please feel free to call us at 310-318-7151 California time, and we will be glad to discuss your project free of charge.

Best regards,

The Engineering Team at E&S Grounding Solutions


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