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  1. tofulover

    Step-up transformer = Star-grounded LV / Star-grounded HV. How to calculate EPR?

    Many thanks 7anoter4. Appreciated your diagram above.
  2. tofulover

    Step-up transformer = Star-grounded LV / Star-grounded HV. How to calculate EPR?

    Hi Waross, what would be the steps then for me to determine the EPR in my case? Some high-level steps would be most appreciated.
  3. tofulover

    Step-up transformer = Star-grounded LV / Star-grounded HV. How to calculate EPR?

    Thanks for your reply. I agree with what you said. Much appreciated.
  4. tofulover

    Step-up transformer = Star-grounded LV / Star-grounded HV. How to calculate EPR?

    Thanks. If there is a SLG on the HV side - in this case 0.5kA, does this 0.5kA then go back to the neutral of the star side of the HV winding only? Does the 0.5kA HV SLG fault affect the LV side at all?
  5. tofulover

    Step-up transformer = Star-grounded LV / Star-grounded HV. How to calculate EPR?

    may be a silly question from me - wouldnt the 20kA SLG at LV side - most of the fault current will return via the earthing cable and then via the MEN back to the neutral of the generators being the source?
  6. tofulover

    Step-up transformer = Star-grounded LV / Star-grounded HV. How to calculate EPR?

    Hi, I am looking at a pre-existing electrical system which is an off-grid microgrid. This consists of 3 off low voltage 415V 500kVA generators feeding into 1 off 2000kVA 415V/11000V step up transformer to then connect to 11kV infrastructure for a small village. The 3 off generators at LV...
  7. tofulover

    LFI AC interference calculations using Australia Standards AS3835 and HB101 (and HB102) vs AS4835

    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...
  8. tofulover

    Operating temperature of PVC conduit for X90 and X110 rated XLPE cables

    Thanks for your comments. Sounded very logical to me!
  9. tofulover

    Operating temperature of PVC conduit for X90 and X110 rated XLPE cables

    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...
  10. tofulover

    Zigzag TX rating - Westinghouse T&D vs IEEE C62.92

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

    Zigzag TX rating - Westinghouse T&D vs IEEE C62.92

    Thanks dpc.
  12. tofulover

    Zigzag TX rating - Westinghouse T&D vs IEEE C62.92

    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...
  13. tofulover

    Zigzag TX rating - Westinghouse T&D vs IEEE C62.92

    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...
  14. tofulover

    CDEGS - FDIST - how to specify transmission and distribution feeders using underground cables?

    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...
  15. tofulover

    Multiple 11kV 2.5MVA emergency standby Generators - Earthing strategy

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

    Multiple 11kV 2.5MVA emergency standby Generators - Earthing strategy

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

    Multiple 11kV 2.5MVA emergency standby Generators - Earthing strategy

    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...
  18. tofulover

    Multiple 11kV 2.5MVA emergency standby Generators - Earthing strategy

    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...
  19. tofulover

    Multiple 11kV 2.5MVA emergency standby Generators - Earthing strategy

    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...
  20. tofulover

    Multiple 11kV 2.5MVA emergency standby Generators - Earthing strategy

    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...

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