How accurate are digital meggers ?
How accurate are digital meggers ?
(OP)
Today, I had the uneasy experience of meggering a generator rotor winding (same temperature, time span of 10 minutes, same voltage of 500 V) with 3 different digital meggers (Two Fluke USA and one Kyoritsu Japan)and getting 3 widely differing values of about 600 megohms, 1500 megohms and 5000 megohms.
Is the case of no two clocks show the same time ? Is it time then to go back to the old & trusty hand-cranked analog meggers ?
Is the case of no two clocks show the same time ? Is it time then to go back to the old & trusty hand-cranked analog meggers ?
Muthu
www.edison.co.in





RE: How accurate are digital meggers ?
Muthu
www.edison.co.in
RE: How accurate are digital meggers ?
Check the resistance function at a few points. Check the output voltage function.
By the way... make sure the battery is charged before you begin testing, too.
old field guy
RE: How accurate are digital meggers ?
These meters are less than two years old and come with a 2-year OEM calibration validity.
And yes, their batteries were fully charged too.
I still have my old original motor operated Evershed Vignoles "megger" . Plan to use that as a calibrator and see how these "state-of-the-art" digi meggers fare.
I must admit that my trust in all digital metering is taking a beating today.
Muthu
www.edison.co.in
RE: How accurate are digital meggers ?
RE: How accurate are digital meggers ?
Yes, I discharged between the tests (though it was only 500 V and the winding is pretty much like LV motors - no solid insulation like MV motors for much of polarization to take place). And I repeated the test and the values are in the range I've posted. Well, at least they're consistent in their errors, I guess. :)
Muthu
www.edison.co.in
RE: How accurate are digital meggers ?