Megger

Discussion in 'General Electronics Chat' started by Treeman, Mar 29, 2015.

  1. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    Hi,
    I have an old Megger that was given to me. I understand that it is used for testing shorts in Hi voltage lines. You wind the handle and it the ohmmeter falls if there is a short in the winding. I read a bit on the net but was not much wiser.
    I think I probably have no use for this ever - so what can I do with it that's fun?
    It puts out 1.5v with a good wrist action.
     
  2. ericgibbs

    Senior Member

    Jan 29, 2010
    2,499
    380
    The early Megger produce a very high voltage, depending how fast you turned the handle and was used to check circuit insulation.
    Post a picture or model number.
    E
     
  3. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    Thanks Eric. I got her up to 2 volts that's as fast as I could go. I'm thinking along the lines of using it as a switch maybe. Wind the handle turn on a transistor , some sort of simple circuit after - a timer probably!
     
  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    1,438
    368
    The text on the front suggests that you should be getting "500 Volts".
     
  5. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    I agree! This may be a case of If it is broke don't fix it!
    What could be broken so that it gives 2v instead of 500v?
     
  6. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    Well that could be fun; but I'd rather amuse myself by creating something meaningful to me not the rest of society. I need a life too.
     
  7. ericgibbs

    Senior Member

    Jan 29, 2010
    2,499
    380
    How are you measuring the volts out.?
     
  8. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    on a digital multimeter
     
  9. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,969
    744
    if you have a 1meg or higher resistor,put it across the terminals and try it, it should read the correct resistance.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,503
    2,366
    There were two types of megger of this era, one was high voltage insulation tester, which you have, and the handle is cranked at a certain rate to provide 500vac, at this point an internal clutch kicks in to maintain the 500v.
    The second type was a resistance meter, used mainly for ground path measurements, down to fractions of an ohm, and operated on lower voltage.
    They are fairly simple instruments so if you don't get anything out you could open it and take a look.
    Max.
     
    Last edited: Mar 29, 2015
    Lundwall_Paul likes this.
  11. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    With the output leads open, what are you reading on the meter? (of course, while cranking)
     
  12. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    The needle seems a bit floaty and sits around 1Meg all the time. In fact it seems to respond to gravity depending on orientation! It does respond to a crank though and if Zeroed by turning on its side and then laying flat carefully (!) it winds up to 1Meg and lives happily.
    Maybe this is not correct - seems likely.....
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,503
    2,366
    Connect it to a AC rated capacitor such as a 1ph motor cap and while cranking it whip the leads off, then short the terminals with a screw driver.o_O
    Max.
     
  14. Treeman

    Thread Starter Member

    May 22, 2014
    158
    15
    Do I have any of that lying around with the rest of the junk Max?
    Seems like a bad idea.
     
  15. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    The Megger you have seems to be labeled 500 Volts like most of its type.

    Ron
     
  16. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    My guess is that the cap inside the megger has become leaky. I remember we would "indoctrinate" a fresh trade school grad by showing him how a megger worked. We would hold the leads and have him crank it. Then, we would have him hold the leads, but would start cranking it before he could get his hands on both leads. Those were the good ol' days.
     
    Treeman likes this.
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,503
    2,366
    When I was a young apprentice we charged a cap up with the megger and left it on the bosses desk!!:p
    Max.
     
    Treeman likes this.
  18. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    The high resistance test generates 500V when you wind the handle, so you can charge up capacitors and leave them for people to find - but you have to pull the test clip off before you stop winding or it discharges through the meter.
     
  19. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Nowadays its easier to use the inverter from a disposable camera - smaller and more discrete.
     
  20. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    You'd get more excitement charging up a 385V 560uF reservoir electrolytic - but you'd have to stand there winding the handle an awfull long time!
     
    Treeman likes this.
Loading...