High Resistance Grounding: Neutral conductor contribution to 3-phase charging current?
High Resistance Grounding: Neutral conductor contribution to 3-phase charging current?
(OP)
Greetings:
The generator neutral conductor of a HR grounded system is rated 5kV, 1/C, #2/0, 100'. In totaling the system capacitance, how can it reasoned to include the shunt capacitance of the neutral conductor? Under balanced operation, the voltage across the neutral should be zero, which shouldn't permit the shunt capacitance to charge (Vng=0). During the fault this becomes Vng = Vln, providing a charging current. Can the shunt capacitance (a zero-sequence neutral to ground) be added in parallel with those in the unfaulted phases? Thanks for your thoughts.
The generator neutral conductor of a HR grounded system is rated 5kV, 1/C, #2/0, 100'. In totaling the system capacitance, how can it reasoned to include the shunt capacitance of the neutral conductor? Under balanced operation, the voltage across the neutral should be zero, which shouldn't permit the shunt capacitance to charge (Vng=0). During the fault this becomes Vng = Vln, providing a charging current. Can the shunt capacitance (a zero-sequence neutral to ground) be added in parallel with those in the unfaulted phases? Thanks for your thoughts.






RE: High Resistance Grounding: Neutral conductor contribution to 3-phase charging current?
RE: High Resistance Grounding: Neutral conductor contribution to 3-phase charging current?
RE: High Resistance Grounding: Neutral conductor contribution to 3-phase charging current?
The generator is neutral grounded through a high resistance scheme (through a distribution transformer, 10 kVA, 4160/240V, with 4.2ohm on the secondary.).
My main question was: given that the components which determine Xco (the 3-phase capacitive reactance) are coming from the 3-phase system, how can I add in the contribution from the neutral conductor (a 5kV, 1/C, #2/0, 100' cable, which would create a shunt capacitance to ground, even though Vng = 0 under normal balanced conditions), when this is a "neutral to ground" quantity and shouldn't be lumped with the "3-phase" shunt capacitive quantities?
Thanks for your thoughts.
RE: High Resistance Grounding: Neutral conductor contribution to 3-phase charging current?
During a fault, the return current will go through the neutral grounding resistance then back to the winding X0 point and your neutral and the earth bond together so they are at the same potential.