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    4160V cubical

    I think I know the answer but wanted a 2nd opinion. I have a 4160 volt breaker cubical, the breaker has been removed and I have a project to upgrade the overcurrent relay. The shutters are closed and the PT fuses pulled. The back of the bus is still energized. The arc flash is a catogory 3 if I'm working on the breaker. If I'm doing the relay install do I still need Cat 3 gear? I say yes, even though its a pain in the butt to wire up relay with all that gear. I'm I over thinking things here?

    #2
    Tables or arc flash study? If you are going off the results of the arc flash study the control section where the relays are should have a separate label, if not check the study results, it should be in there.

    My question is why do you have to rewire anything to replace a relay? Just pull it out of the case and replace (After using the shorting block/switches of course)

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      #3
      Originally posted by zog View Post
      Tables or arc flash study? If you are going off the results of the arc flash study the control section where the relays are should have a separate label, if not check the study results, it should be in there.

      My question is why do you have to rewire anything to replace a relay? Just pull it out of the case and replace (After using the shorting block/switches of course)
      I would think that if a risk assessment of the job is done, one may find that there is no arc flash risk as there are no exposed energized conductors. CT wiring should have no voltage on it since the load is de-energized.

      As far as rewiring, I can see that if an old electromechanical relay is being replaced with a modern microprocessor based relay....new case, maybe outputs...etc.

      Comment


        #4
        Originally posted by wbdvt View Post
        I would think that if a risk assessment of the job is done, one may find that there is no arc flash risk as there are no exposed energized conductors....
        Agreed.

        There are no exposed conductors nor are you interacting with any equipment in any way that may cause a failure.

        We sometimes see customers' in-house requirements that far exceed those of 70E, so be aware of that, but otherwise we routinely do relay swaps under identical circumstances with no flash or voltage PPE because those risks are not present.

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          #5
          I like the draw out relays, but our engineers decided they wanted to use Siemens 7sj82 relays. That why I have the rewire.

          Comment


            #6
            There are plenty of options for multifunction microprocessor based relays that are direct replacements for old EC styles that plug and play into the old case with no wiring, easiest way to upgrade.

            Comment


              #7
              Originally posted by zog View Post
              There are plenty of options for multifunction microprocessor based relays that are direct replacements for old EC styles that plug and play into the old case with no wiring, easiest way to upgrade.
              But they may not be what the customer wants, or is standardized on, now.
              Just because you can, doesn't mean you should.

              Comment


                #8
                Originally posted by jim dungar View Post
                But they may not be what the customer wants, or is standardized on, now.
                True, easy for the EE to say who doesn't have to rewire everything Bet cornbread would prefer direct replacement ha ha.

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                  #9
                  Originally posted by zog View Post
                  True, easy for the EE to say who doesn't have to rewire everything Bet cornbread would prefer direct replacement ha ha.
                  So true Zog, you know us EE's can get awed by all the options and data available....whether it be used or useful is another discussion!

                  Comment


                    #10
                    Originally posted by wbdvt View Post
                    So true Zog, you know us EE's can get awed by all the options and data available....whether it be used or useful is another discussion!
                    See that everyday, communicating trip units with ZSI but nothing even hooked up in the cell. Big $ options that never get used.

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