Herivelto,
The non-zero happens due to high DC off set meaning very high X/R ratio. Depending on the transformer design meaning its X/R ratio,
it may happen.
If we are going to break the current during the short in-rush duration, then the non-existence of current zeros may be a problem for the...
CLEAN EARTH was an old idea when the manufacturers were not able to explain some erratic behavior
of process control units. It is no longer valid now. Bond them together to make an equipotential.
Also by separating them 5m in the soli do you think that it is possible to stop influencing the other?
I have no further comments until I see the transformer connections (vector group) at the other end of all feeders H01 to H06 feeders which I have already requested
from newelecteng by my post on 28 Sep
1)Yes, you are correct. It is 2400V to ground.
Therefore, no questions. You cannot use a 2400/4160Y PT on an impedance grounded system.
Instead you have to use DUAL bushing, 5kV class, indoor or outdoor
with a VTR=35 if your secondary system is 120V AC.
Therefore, rated primary accuracy...
beyond86
Yes, but does it mean that the 33kV system has got 643A as charging current?
How do you account for that?
Before I make any further comments I am curious to know,
1) Is the 33kV system a real "DELTA" system?
2) Does the 33kV system really needs an earthing transformer?
3) If yes, how...
beyond86,
Yes I noted it. See the feeder relay results.
Io_calc =643.458(A) meaning 3I0=1929Amps is the earth fault current.
How do you justify that amount of large earth fault current if the 33kV side is DELTA?
If the 33kV system is really a DELTA bus then there is only the charging current...
newelecteng:
I noted the following.
From the incomer relay, I Found that U0=14407.808(V)=14.4kV
Per your SLD the incomer is solidly grounded. Therefore,U0 cannot be 14.4kV.
It should read 76kV.
Per SLD there is no VT at the 132kV side.
Any comments?
newelecteng:
Few questions to you please.
1)What is the reason for using WYE EARTHED transformer for the 132kV side?
2)Are all feeders H01 to H06 connected to generators exporting power to 132kV side or are they normal feeders connected to typical loads?
3)What is the vector group of the...
1) What is the earthing method of your 33kV system?
2) You have mentioned that an earthing transformer ZNyn1 is feeding your 400V system. Bit unusual for me. Could you please upload your SLD?
1) You are correct. The existing grounding transformer is directly connected to the existing 12.47kV distribution system.
Per the given SLD, currently, the existing 12.47kV distribution system is ALREADY effectively grounded
(Utility will not tolerate non-effectively grounded systems) and...
I donot know what you meant by frequency scan in insulation coordination study. Normally it is for harmonics.
You can do the equivalent calculations of protective margins (PRL1, PRL2, PRS) for the surge arrester using a EMTP software.
After modeling the substation at least for 5 spans, you allow...
Since your T2 is solidly grounded and single phase loads are served, any GF current will return back to the NEUTRAL of
T2. Therefore, your 480V system fed by T2 is eff. grounded irrespective of T1 grounding method.
If you perform a SC study you will find that COG of T2 system is less than 85%.
