I refer to the last post by electricpete - many thanks for your input.
The issue is "A", one design. So why would a particular design have this behaviour? I would have expected the ratio to be maintained at any flux density. I base this thinking on the transformer equation
E = 4.44 Beta X area X...
My general approach is to give the CT manufacturer all the information regarding ratio, fault level, accuracy class, relevant relay requirements, etc, and let them play between the KPV and Rs to get the most economical solution.
Many thanks for the comments.
Scottf, the unit is great at 2000 volts, using the CPC100, but this is not readily available to me. So I usually use the multimeter test at 100 volts, and this is where the large error occurs - but only on this VT. On most VTs the results with multimeters is...
Many thanks for your comments they are much appreciated.
Regarding instruments: At voltages up to 600 volts I used Fluke 175 true RMS multimeters,swopping the HV and LV meters around in case one was faulty. I then managed to get an Omicron CPC100 test set,which is able to go up to 2000 volts on...
When testing voltage transformers and their associated wiring I normally apply about 1% of the rated primary voltage and get a secondary voltage exactly primary voltage divided by the VT ratio. On some transformers however, I get ratio errors of up to about 10% when doing this. If I then...
