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    Originally posted by Sahib View Post

    Ok. But the OP must bond the POCO neutral to the 600V SWbd ground instead of at 13.2KV SWbd to have single point grounding.
    I have been trying to say this and also I cannot find it in NEC 2014 that 600VAC or less than 1000V system is required to be single point only. If anyone can find it then would maybe justify 600Vac N to G.

    Comment


      Originally posted by electrofelon View Post

      I think I already gave some plausible justification for that N-G bond in the 600V switchboard: 1) Call it an SDS (which IMO is a silly distinction that a field installed connection doesnt make it an SDS where has factory installed does) 2) use 250.30(A)(1) exception 2. As I said, this is not fully correct and may be a stretch to some people.
      Post #66 attachment xfmr nameplate their is some sort of neutral disconnect i wonder if that can separate factory install internal x0/h0 bond?

      I dont see how even with factory install internal bond x0/h0 neutrals are connected directly and xfmr is Not SDS. Based on post #2 Hv&Lv who says he/she does this everyday I have attempted to draw attached sketch 13.2kv concentric neutral is indirectly connected thru Earth ground ring electrode to 600V X0/H0 terminal exists on secondary side per post #66 xfmr nameplate and post #2. Their is no H0 connection 13.2kV primary side, concentric neutral are grounded and H1, H2, H3 are phase conductors only no neutral. Am I missing something? Hv&Lv can you help or anyone else? Unless you do #2 attachment in which case i guess one would remove conductor going from G bar 13.2kV to 600V swbd G bar?
      Last edited by hhsting; 12-03-19, 09:49 AM.

      Comment


        Originally posted by hhsting View Post

        Post #66 attachment xfmr nameplate their is some sort of neutral disconnect i wonder if that can separate factory install internal x0/h0 bond?

        I dont see how even with factory install internal bond x0/h0 neutrals are connected directly and xfmr is Not SDS. Based on post #2 Hv&Lv who says he/she does this everyday I have attempted to draw attached sketch 13.2kv concentric neutral is indirectly connected thru Earth ground ring electrode to 600V X0/H0 terminal exists on secondary side per post #66 xfmr nameplate and post #2. Their is no H0 connection 13.2kV primary side, concentric neutral are grounded and H1, H2, H3 are phase conductors only no neutral. Am I missing something? Hv&Lv can you help or anyone else? Unless you do #2 attachment in which case i guess one would remove conductor going from G bar 13.2kV to 600V swbd G bar?
        No takers no one knows?

        Comment


          Originally posted by hhsting View Post

          Their is no H0 connection 13.2kV primary side, concentric neutral are grounded and H1, H2, H3 are phase conductors only no neutral.

          I am having a hard time following this. The section I quoted above, is that a question about a possibility or a statement about how it is? Can you please post a good quality image of the entire drawing from post #36? We should have had this in the OP.

          I am rather lost at this point. This has been going on for so long and your responses are really hard to follow and we dont have the complete drawing. I cant remember what has or has not been established and I dont have time to go back and study all 8 pages. Submit the complete drawing and I will try once more to say if I think it is correct.

          I think the main point of confusion is that happens on each end of the concentric neutral.
          Ethan Brush - East West Electric. NY, WA. MA

          "You can't generalize"

          Comment


            Originally posted by electrofelon View Post


            I am having a hard time following this. The section I quoted above, is that a question about a possibility or a statement about how it is? Can you please post a good quality image of the entire drawing from post #36? We should have had this in the OP.

            I am rather lost at this point. This has been going on for so long and your responses are really hard to follow and we dont have the complete drawing. I cant remember what has or has not been established and I dont have time to go back and study all 8 pages. Submit the complete drawing and I will try once more to say if I think it is correct.

            I think the main point of confusion is that happens on each end of the concentric neutral.
            Drawings are still being revised I dont have any new.

            Statement is a possibility I am not sure i am asking following based on what is shown on xfmr nameplate post #66 and what post #2 says: If I am looking at 2000kVA 13.2kV xfmr primary compartment/door in field I should only see H1, H2, H3 for three phases and concentric neutrals from each phase bond to ground no other place for it and NO H0 and when I go to 600V xfmr secondary compartment/door I should only see X1, X2, X3, H0/X0 correct?

            My second question if their is no H0 connection primary 13.2kV only H0/X0 secondary then attachments post #107 are they consider SDS system and wired correctly?

            Comment


              Originally posted by hhsting View Post

              If I am looking at 2000kVA 13.2kV xfmr primary compartment/door in field I should only see H1, H2, H3 for three phases and concentric neutrals from each phase bond to ground no other place for it and NO H0 and when I go to 600V xfmr secondary compartment/door I should only see X1, X2, X3, H0/X0 correct?

              My second question if their is no H0 connection primary 13.2kV only H0/X0 secondary then attachments post #107 are they consider SDS system and wired correctly?
              It depends. Sometimes in the HV compartment they will have a HO bushing with a removable strap to the case, and sometimes there will not be an HO bushing, just a ground lug on the case. In LV compartment there will be an XO spade, almost always with a removable ground strap to the case.

              please un-secret the entire drawing you showed a piece of in post #36.
              Ethan Brush - East West Electric. NY, WA. MA

              "You can't generalize"

              Comment


                Originally posted by hhsting View Post

                I have been trying to say this and also I cannot find it in NEC 2014 that 600VAC or less than 1000V system is required to be single point only. If anyone can find it then would maybe justify 600Vac N to G.
                Why don't you just remove the 600v N to G connection and keep the single point grounding per your option2 drawing in consultation with the utility?

                Comment


                  The utility has the final say. But remember if there is no H0 bonding, you could have floating neutral problem on your side due to presence of Y-Y transformer.

                  Comment


                    Originally posted by Sahib View Post
                    The utility has the final say. But remember if there is no H0 bonding, you could have floating neutral problem on your side due to presence of Y-Y transformer.
                    Can you elaborate on this floating neutral problem?

                    This is one major problem with this design, is that it is based around a wye wye transformer with a specific grounding and bonding arrangement, and not being an expert at MV and wye wye transformers, I am reluctant to endorse rearranging the grounding and bonding just to meet NEC requirements.
                    Ethan Brush - East West Electric. NY, WA. MA

                    "You can't generalize"

                    Comment


                      Originally posted by electrofelon View Post

                      Can you elaborate on this floating neutral problem?

                      This is one major problem with this design, is that it is based around a wye wye transformer with a specific grounding and bonding arrangement, and not being an expert at MV and wye wye transformers, I am reluctant to endorse rearranging the grounding and bonding just to meet NEC requirements.
                      Suppose the 13.2KV side neutral point is not connected to POCO source neutral by bonding to grounded 13.2KV incoming cable shield. If there is any ground fault on 600V side, the protective device may not operate as there is only a small increase in current from inverter side and no contribution to ground fault current by POCO side as the faulted phase is pulled down to ground potential and there would be phase to ground over voltages on other two phases of 600V side.
                      Last edited by Sahib; 12-02-19, 11:52 AM.

                      Comment


                        Attached is second page of datasheet transformer: LV compart only has H0/X0, X1, X2 and X3. HV compart only has H1, H2, H3. By the way concentric neutral should be bonded to incoming POCO concentric neutral as stated in NEC 2014 Article 250.186(A) at 13.2kV SWBD. Service point is at 13.2kV SWBD. The question is lets say I have three cable each with concentric neutral on the HV compartment I only have H1, H2, H3 and ground bar. Where does the concentric neutrals of each phase go to?

                        Last edited by hhsting; 12-03-19, 10:07 AM.

                        Comment


                          hhsting, I humbly suggest that you hire a consultant with expertise and experience in this sort of thing rather than posing questions on the internet and trying to figure it out for yourself. MV can do a horrific amount of damage when something goes wrong.

                          Comment


                            Originally posted by hhsting View Post
                            The question is lets say I have three cable each with concentric neutral on the HV compartment I only have H1, H2, H3 and ground bar. Where does the concentric neutrals of each phase go to?

                            The the ground lug in the HV compartment. I am beginning to think that this WOULD BE an SDS, if you call that concentric conductor an EGC and not a neutral. When the definition of SDS and wye wye come together, things get kinda screwy and into semantics. So I am leaning towards: HV switchboard N-G bond, 3 phases plus EGC (concentrics used as EGC per 250.190(C)(2)) to transformer, then make N-G bond for SDS in transformer, then to LV switchboard probably with separate N-G depending on your reading of that exception in 250.30(A).

                            Ethan Brush - East West Electric. NY, WA. MA

                            "You can't generalize"

                            Comment


                              Originally posted by ggunn View Post
                              hhsting, I humbly suggest that you hire a consultant with expertise and experience in this sort of thing rather than posing questions on the internet and trying to figure it out for yourself. MV can do a horrific amount of damage when something goes wrong.
                              My fee is reasonable, just keep updating the thread this time.

                              To summarize I think we are really discussing 3 options:
                              Click image for larger version

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                              Comments based on 2017 NEC unless otherwise noted.

                              Comment


                                Originally posted by tortuga View Post

                                My fee is reasonable, just keep updating the thread this time.

                                To summarize I think we are really discussing 3 options:
                                Click image for larger version

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                                Can you attach a higher quality version?
                                Ethan Brush - East West Electric. NY, WA. MA

                                "You can't generalize"

                                Comment

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