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davechow
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Join Date: Dec 2013
Posts: 10

Data Center VTs Failure

12/07/2013 12:10 AM

Our data center has a VT failure (phase A only) every two months or so in a different location. Each set of VTs connected Yg-Yg 34kV/380V. I have noticed floating ground in some locations. What can be the cause?
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TonyS
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#1

Re: Data Center VTs Failure

12/07/2013 6:04 AM

What is the VT used for?

Yg Yg to me seems strange Y Y with one leg earthed (grounded) on the secondary is the norm in the UK.

Can you give more information?

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jack of all trades
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#2

Re: Data Center VTs Failure

12/08/2013 2:16 PM

More information is required, such as what side of the transformer they are connected to, if you are overloading the output of Phase A VT, etc.

If I had to guess I would say they are failing due to voltage spikes or over voltage (eg- power quality issues).

Have you considered connecting up a voltage data logger?

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Instruform
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Join Date: Feb 2009
Posts: 35
#3

Re: Data Center VTs Failure

12/09/2013 4:03 AM

Does the "floating ground" mentioned mean that the system has a distorted neutral, how was this detected?

"Snap shot" checks of the 6 secondary voltage measurements-3 line to line & 3 line to earth at different VT locations might yield some important indications of what your problem is.

Recommend you peruse my thread on Tarrif metering with earthed VTs.

Your VTs may require inversion damping.
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