No one to my knowledge (and I work for an instrument transformer company in the US) makes PVT's above 230 kV. At 345 kV about the best you're going t oget is a VT with a thermal burden of about 10 kVA at most. We have sold some in 3-phase sets to deliver a 3-phase power of 30 kVA.
To DPC's question, it is possible to have a PVT with a metering winding. The metering winding can be set to be accurate at full load (i.e. when the PVT is supplying station power) or it can be set to be accurate when the PVT is not supplying station power. A typical application is to have the PVT as a back-up source for station power, in which it is used under normal conditions for metering/protect, and in the event of loss of primary station power, it can step and provide needed power. Of course, under this arrangement it will not deliver metering accuracy when used for station power.
ABB got out of PVTs in the US when they closed their plant in Bloomington, IN. They are really on in instrument transformers now up to 34.5 kV in the US.
DPC-
I'm pretty sure Trench does not. You can check with them, but I'm about 99.9% sure they don't. I work for Ritz (now part of Areva) and we are only 1 of 2 companies that go up to 230 kV for PVTs for the North American market.
Yes...ABB still has HV IT's outside of the US. I believe they produce in Sweden, in addition to other factories around the world.
pcwebb,
Check with Kuhlman. They are making station service transformers that have a high primary voltage for applications that are remote. Don't know if they can get the accuracy you need though.