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    Megger

    http://www.netaworld.org/
    http://www.nema.org/
    Last edited by George Stolz; 05-07-08, 08:03 PM. Reason: Brian requested the correction of the value of a trillion ohms
    Brian John
    Leesburg, VA

    #2
    FIRST POST WAS TOO LONG.......


    What megger should you buy?

    In my opinion there are 3 basic meggers I would consider

    All should have variable testvoltages up to 1000 VDC, be digital with analog scale, 2000 megohms or more full scale readings. And just my experience buy a Fluke, AVO Biddle Megger, or AEMC brand. Additionally I would recommend calibration of you megger, multimerter and amp clamp at least every few years (we cal all our equipment yearly). Figure on spending between 300.00-700.00 dollars. Obviously the better meters with options to include multiple test voltages are going to cost you... Get a good case and hopefully treat it like you do your multimeter (which is like you life depends on it, because it does). At a minimum select an insulation resistance tester, with 250, 500, 1,000 VDC ranges a tester with 100 VDC would be included in any megger I purchase.
    Fluke and AEMC do not mention the Trade name Megger [I think] they list these testers as insulation resistance testers Megohmmeters.
    AEMC
    http://www.aemc.com/techinfo/Charts/...ison_Chart.pdf
    Megger
    http://www.biddlemegger.com/cgi-bin/...nk--bi2820.htm
    Fluke
    http://us.fluke.com/usen/products/categoryinsul.htm
    -------------------------------------------------------------------------------------------------------------------------------------
    The best way to familiarize yourself is to test everything and document your results (for many reasons) and test often. Play with the tester. If the results seem questionable, question yourself, your test procedures, check the megger, leads apart then leads shorted.
    Additional reading:

    AEMC
    http://www.aemc.com/techinfo/techwor...ech_megohm.pdf

    Megger
    http://www.omnicontrols.com/articles...ch_in_Time.pdf

    Fluke
    http://support.fluke.com/find-sales/...15_ENG_C_W.PDF

    Additional reading
    http://www.hipot.com/faqs/insulation.shtml
    http://ecmweb.com/mag/electric_testi...ave/index.html
    http://www.sefelec.com/en/insulation...tance-test.php
    http://bg.ecmweb.com/ar/electric_ins...ting/index.htm
    Brian John
    Leesburg, VA

    Comment


      #3
      The paper test (about the 5th time posted here) but it is sooo much fun to set fires.

      Double click on the image below.

      Brian John
      Leesburg, VA

      Comment


        #4
        Megger

        Good post Brian, the megger is required tool for commissioning and testing gear, equipment and systems. Even though we have all our gear, motors and large cables tested by an independant test co. I still like to check again before we energize. It is important to document your readings, it may come in handy down the road.

        Charlie

        Comment


          #5
          Originally posted by brian john
          ICircuit breakers disconnects, motor starters - with the load disconnected, pole to pole line, pole to pole load, line to load (CB open).
          ---
          Well done Brian, I was thinking we needed a good FAQ on this topic. I have to point out that on breakers/starters, it should be Phase to Phase (Breaker closed), Phase to Ground (Breaker closed) , line to load (Breaker open)

          I have some good stuff on the 3 currents measured, I will post and you can add if you like.

          Comment


            #6
            Please add and post corrections as necessary.
            Brian John
            Leesburg, VA

            Comment


              #7
              ". . .it is sooo much fun to set fires."

              Brian John, I would think you will soon be hearing from Charlie Eldridge.

              "I know we are all electrical professionals; however, everyone who reads these posts is not necessarily an electrical professional. I would hope that no one would be stupid enough to actually follow your advice. Assume for a moment that there was enough impedance in the circuit to delay the overcurrent device for the circuit from opening; have you caused someone to start a fire? OK, assume the available fault current was high enough to do as you have suggested; has the practical joker been aware that maybe there shouldn't be anything around that would catch fire?

              I know I am coming down with both feet but this is something for either an accident or a test bench, not to be done on purpose to someone with limited electrical knowledge.
              __________________
              Charlie Eldridge, Indianapolis, Utility Power Guy"

              Comment


                #8
                Some more app's,....

                Here's some more application notes for anyone else interested.


                http://us.fluke.com/usen/support/app...(FlukeProducts)


                Enjoy!
                Old and in the Way.......

                Comment


                  #9
                  Originally posted by Lxnxjxhx
                  Brian John, I would think you will soon be hearing from Charlie Eldridge.

                  "I know we are all electrical professionals; however, everyone who reads these posts is not necessarily an electrical professional. I would hope that no one would be stupid enough to actually follow your advice. Assume for a moment that there was enough impedance in the circuit to delay the overcurrent device for the circuit from opening; have you caused someone to start a fire? OK, assume the available fault current was high enough to do as you have suggested; has the practical joker been aware that maybe there shouldn't be anything around that would catch fire?

                  I know I am coming down with both feet but this is something for either an accident or a test bench, not to be done on purpose to someone with limited electrical knowledge.
                  __________________
                  Charlie Eldridge, Indianapolis, Utility Power Guy"
                  Huh? What are you talking about, he is talking about a test bench. And why are you using Charlies signature?

                  Comment


                    #10
                    Originally posted by brian john
                    The paper test (about the 5th time posted here) but it is sooo much fun to set fires.

                    Double click on the image below.

                    That is a painfully slow scroll. I gave up waiting for the fire.
                    BB+/BB=?

                    Comment


                      #11
                      Brian
                      Thank you for taking your personal time to help us all out with the what now seems to be a common topic, "meggers".
                      Instructor, Industry Advocate

                      Comment


                        #12
                        Originally posted by brian john
                        There are additional megger types for special test, but I have not included these as they are outside the scope of what the average electrician should have in his “tool case”
                        Brian,

                        I would also like to thank you for taking the time it
                        obviously took to put together this educational post.

                        I am a little confused on the relationship with another
                        form of testing, earth-ground testing. I have heard
                        a number of times, "you can test ground resistance
                        if you have a megger.", including on a post this evening
                        about ground rods.

                        E.g. ground and insulation testers are aimed at opposite
                        ends of the resistance scale, although I have yet to
                        ascertain what voltage earth ground resistance work at
                        which is leaving some unclarity in my mind.

                        I have read through manufacturer literature on ground
                        testing (pointed at from you in another post - thanks!).
                        It appears to me that while Megger (and AEMC, Fluke)
                        manufacturers both insulation testers and ground testers,
                        these functions are completely distinct. Is this correct?

                        Sorry if this is kind of a newbie question, but I wanted to
                        make sure I had this straight next time someone talked
                        about testing ground resistance with a "megger".

                        Thanks.

                        Comment


                          #13
                          Originally posted by rexowner
                          Brian,

                          I would also like to thank you for taking the time it
                          obviously took to put together this educational post.

                          I am a little confused on the relationship with another
                          form of testing, earth-ground testing. I have heard
                          a number of times, "you can test ground resistance
                          if you have a megger.", including on a post this evening
                          about ground rods.

                          E.g. ground and insulation testers are aimed at opposite
                          ends of the resistance scale, although I have yet to
                          ascertain what voltage earth ground resistance work at
                          which is leaving some unclarity in my mind.

                          I have read through manufacturer literature on ground
                          testing (pointed at from you in another post - thanks!).
                          It appears to me that while Megger (and AEMC, Fluke)
                          manufacturers both insulation testers and ground testers,
                          these functions are completely distinct. Is this correct?

                          Sorry if this is kind of a newbie question, but I wanted to
                          make sure I had this straight next time someone talked
                          about testing ground resistance with a "megger".

                          Thanks.

                          Don't feel bad for asking that question Rex. Testing ground resistance with a megger:confused: I'd love to hear more on that. Never even heard that discussion before!!!!!!!!!!!
                          Old and in the Way.......

                          Comment


                            #14
                            Originally posted by 76nemo
                            Don't feel bad for asking that question Rex. Testing ground resistance with a megger:confused: I'd love to hear more on that. Never even heard that discussion before!!!!!!!!!!!
                            It's in the fifth message on this post tonight:
                            http://forums.mikeholt.com/showthread.php?t=99235
                            I don't mean to pick on anyone - the poster is probably
                            just referring to the Megger brand of earth ground testers,
                            and it's really more of a side point than a main point,
                            but since "megger" usually means an insulation tester,
                            I find it somewhat disorienting because I am only
                            currently learning about these testers.

                            I also heard it at an solar class about a year ago, but
                            that was before I understood anything about meggers
                            (which I basically learned from this forum and the
                            pointers to other materials posted) and to be honest I
                            didn't have a high degree of confidence in that instructor.
                            Last edited by rexowner; 05-06-08, 12:42 AM.

                            Comment


                              #15
                              Digital analog megger 250 VDC-5,000 VDC with close up of meter.






                              Hand Crank/120 VAC line voltage analog megger.





                              Battery/120 VAC line voltage Analog




                              Voltage selection on analog meters



                              Fluke Multimeter with Megohmmeter feature 500 VDC and 1000 VDC ranges.



                              Brian John
                              Leesburg, VA

                              Comment

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