HV transformer VT on secondary side? 2

[hallmg]

Hi,

I was wondering why on an HV transforemer,(33KV down to 11KV in this case) the VT is at the secondary side board incomer OCB, there appears to be no VT at the primary feed OCB? Does the VT at the secondary feed the control and protection n the primary then?

 

[davidbeach]

It depends. The best transformer protection is all current based, so the VT isn't truly necessary; desirable, but not absolutely required. If you're going to trip the transformer as backup for uncleared system faults the VT will let you do distance or directional overcurrent.

 

[Power0020]

I doubt the VT is for downstream protection (11 kV), this is usually used for metering purposes

 

[ScottyUK]

Generator transformers require a VT to provide over-fluxing protection. The GSU transformer is almost always going saturate long before the generator stator, and the generator can throw a lot of power into heating the core. It's unusual to see this protection omitted on medium / large GSU transformers, but I'm less certain about smaller embedded machines. If this isn't a generator transformer then I agree with davidbeach's comment.