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Hi everyone, I am wondering for those of us who are based in Australia, could we use the calculation methodology as per HB101 and HB102 for AS3835 to evaluate the AC induction voltages for a pipeline? The AS3835 is titled "Earth Potential Rise - Protection of telecommunications network users...

Thanks for your comments. Sounded very logical to me!

Hi all, Where we use X90 and X110 rated XLPE cables and we "push" the cables to run at a higher ampacity with a higher conductor operating temperature, say we take 80deg in this instance. If we run these cables in PVC conduits (typically buried in-ground), would these PVC conduits not be an...

Thank you all. It is clear now. Appreciated the help.

Thanks dpc.

Thanks VTer. If I calculate the value using the formula you mentioned, i.e. 400A/3 x 11kV x Sqrt(3) = 2540kVA. Surely that is too big a size? Thanks RRaghunath. I also think the IEEE is a bit more correct - but I am not sure why there is such a big discrepancy with the Westinghouse T&D which is...

Hi all, I am trying to size the kVA rating of the zigzag TX. The parameters are: 11kV, Ineutral = 400A, 60sec rating. Based on Westinghouse T&D book, the rating is calculated to be 11kV/sqrt(3) x 400A x factor of 0.104 = 264.2kVA. Based on IEEE C62.92.4:2014, the rating is calculated to be...

Happy new year 2021 to everyone. In the CDEGS FDIST module, I want to define a terminal using underground 11kV cables. I am trying to get to the user interface where it shows the following (the screenshot below is taken from the manual) but I could not find a way how to get to this screen...

Hi everyone, could I please get some comments on my questions? Thanks in advance.

Hi Dave, appreciate if you could spare a moment to review the fault current paths as per above please? Thanks in advance.

Thanks waross. Thanks Dave. I have now saved the higher resolution pictures, accessible via the following links. Could I please trouble you to have a look please? Current paths - fault at generator bus S/C currents for fault at generator bus Current paths - fault at generator winding S/C...

Thanks waross. Appreciated your help. I will double check the input for the zigzag transformer as per your advice. But magnitudes of fault currents aside, could you please have a look at the fault current paths as per my markups above? I would like to know if the fault currents do indeed travel...

Thanks pped, waross, dave. I think I finally got the idea now and to make sure that I actually understand it all, I markup the following sketches to show the current path flowing when the fault is at the generator bus and when the bus is at the internal winding. Could you please have a glance...

Thanks again Dave. Following your recommendation, I have now added a short section of cable from the generator bus to the generator and adding a bus to it. This looks like the following: Then I simulate a generator bus fault and observe the fault levels with 1 x generator connected, 2 x...

Thanks Dave for your comments. Although I work in the IEC world, sadly for HV earthing of generator there are no known IEC standards or references I can draw upon. I stand corrected so if anyone has a suitable IEC references please do tell. The current HV generator earthing design is drawn...

Thanks pped. I actually size the NER the zigzag TX based on 11kV/Sqrt(3) = phase voltage then divide this by 400A to get 15.8877 ohms thereabout. This is what I put into the EasyPower input. I am unclear why you would say that the SLG of 394A will cause the genset to burn beyond repairs? Isnt...

Thanks again Waross. I have carried out a quick analysis using hand-calc and via EasyPower. Could you please have a look below... I am using a 3MVA LeroySomer alternator as an example here and the data sheet indicated the following: X"d = subtransient reactance = 13.7% on 3MVA base = X1 = X2...

Thanks waross for that explanation. In this case would you think that the solution of putting a 10A HRG for the generator and a 400A LRG for the zigzag is the way to go for the generator system as mentioned?

Thanks waross. Just trying to get my head around what you commented. if I have an 10A NER to each generator and a 400A NER to the generator common bus, and therefore any earth fault will be limited to 400A but would the 10A NER to the generator not also limit the earth fault seen by the...

Thanks kiribanda. I am in Australia so yes we will have to follow the IEC standard pretty much but there is very little guidance from the IEC what should/should not do for the HV generator earthing - If you know any suitable standards please let me know. So the bulk of the current proposal is...