neutral earthing

[zub]

Hello all,

We have 4 generators star point grounded through the PT, 8 MVA each. Step up transformers 11/34,5 kV; 8 MVA; Delta-Wye; connected. These four groups paralleled on 34,5 kV bus and one synchronizing breaker connect the bus to the network. The question is we have just one neutral grounding resistor 66 ohm. We connect one of transformers while normal operation. If this grounded neutral transformer tripped in any case an automatic transfer system disconnect the resistor and connect to one of the operated transformer. Is there any inconvienent situation here.
Is there any possibilities to voltage increases between the Phase-Neutral of ungrounded transformers.

If you need more info please ask me.

zub.

 

[zub]

Hi,

Correction: I mean the voltage rising between phase-neutral voltage to phase-phase voltage when a EF occures.

regards.

zub.

 

[gordonl]

As long as there is always one NGR in service the phase to ground voltage wont increase, except for the brief period during change over. (assuming the system is always whole, if the system can split you should look deeper)