Transformer cost vs primary voltage..?

[MD88]

Hi there, does anybody know roughly what the cost differential (in percent) would be for a transformer of a given size, but with alternate primary voltages?

For example, take a 2MVA 600V secondary transformer.. if we take 13.8kV primary as the base, what would be a rough %-adder be for 24.94kV or 34.5kV? Just doing a very high level comparison at the moment, and any input would be much appreciated.

Thanks!

 

[prc]

It varies as (HV1/HV2)^0.3-0.5