cuky2000
Insulation levels are as follows:
HV : 650/275kV (Lightning inpulse/Power frequency)
HVN : -/91.7kV (Lightning inpulse/Power frequency)
According to text in the effectively grounded system the voltage on the healthy phase (in the event of a L-G fault on one of the phases) will rise...
Hi rraghunath
I guess I should explore further whether the solidly earthed source is in fact "effectively" earthed with X0/X1 < 3.0 and R0/X1 <1.0.
If the above is established, I think you are correct that the graded floating neutral will not be subjected to the excessive overvoltages due to...
Thanks rargunath
The 132kV source is indeed solidly earthed.
The 33kV side neutral is earthed through a NER.
33kV side has some big induction motors. The largest being 20MW.
The magintued of the rise on helthy phases for a sigle phase to ground fault will be determined by the system's...
Thanks Ralph
the question remains. Should the xmer neutral be earthed or not given that it has graded insulation.
Your feedbak will be most appreciated.
Regards
This 132/33kV YNynD1 transformer has been operated for years with the HV neutral floating even though the HV primary winding has graded insulation (270kV line and 90kV neutral end) and the HV neutral is brought out. The LV star netral is earthed through NER. Delta tertiary has one tip...
