JacksonburgFarmer said:
Ok...havent got to use it yet, it was to late to mess around in the shop when i got home tonight...long day, changed motor on a silo unloader, the silo was full, so unloader was at the TOP of the silo...7.5 hp motor down the silo (150') was not much fun....but anyhow. When i megger a motor, circuit, or anything, how do I know what is a acceptable reading???? I have a fluke 1507, and understand how to set up the pass/fail, but needing some guidance here.....first time to have a megger....
a couple years ago, i got the 1587... the one you have didn't exist then...
fluke has to come out with a new meter every 51 seconds, it seems....
if you play with it a bit, you'll see that usually the reading goes off the
scale to infinity, but if you are working with an old motor, i've seen
working motors with 20k or so of resistance at 1000v., and the motor
still works... anything less than 1 megohm, and i'd be a bit concerned.
while a megohm on 480 volts won't fault, it's a sign that all is not well
for the future.
if the insulation is really leaky, and you are set at, say, 1000v. you
can see the resistance varying, and the voltage will not come all the
way up to the set voltage. that's a balancing act with a fault.
however, judging by the other posts, it seems marc is the resident
wizard on such things, so i'd like to see what his thoughts are....
i do love my little fluke meter however... after pulling feeders, you
can take 5 minutes, and know for certain things are well..... it's a
whole lot better than the standard "smoke test"..
randy
