What is the voltage of the NEC (zig-zag) trsf? 11kV?
How is it been earthed? Solidly (normally an old system) or through resistors? (newer system)
What is your intention with the test? To see if the NEC is fine? To see if your NEC is connected sufficiently to ground?(It is giving a good grounding point) Or just for relaying purposes?
Voltage is 11kV, earthed through a resistor. All protection checked by secondary/primary injection. Client wants to see that the TX/resistor 'works'. Ideally he would like to induce an 11kV earth fault on his system, but not prepared to take the risk on a working industrial site, so wants another 'real' test method. See the problem?
If the protections are electronic and settable to completely different settings, try connecting a temporary 110V supply (backed up by a GFCI) and simulate the fault.
I think primary and secondary injection for relaying puposes is enough. But if the client still insists on a "real" test, use 380V or a variac. With the ratio you can determine the current, measure it with a clamp-on over the neutral or through the neutral CT while you simulate the fault, and confirm. NEC's are designed to carry fault current usually for 10sec, (sometimes up to 30sec) so a 11kV fault simulation can be done, but do not exceed the time on the nameplate.
