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- Thread starter Darren
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That's an option too. Thanks!
@Darren - that’s was talking about with Megger test - cool they did one
i have never seen it done before, was pretty cool. It started sizzling and vibrating at less than 500v. I'm pretty happy that i decided to go see them. As soon as i walked in they were willing to listen, and wanted to help. I have a good feeling about this. The cost for them to try to save it is minimal, so it's worth a shot.
Brent H
Ultra Member
For all you electrical guys basically megger testing wires or motor windings:
You hit the wire with a voltage well above it’s used specification -
So on the ship we would megger a 600 volt line/motor at 1000 to 1500 volts. The insulation will saturate with that increased voltage (like a capacitor type event) and you can read on the meter what the insulation rating is for what you tested. Typically anything below .5 Mega ohms is cause for immediate repair. We strive for over 500 plus mega ohms.
The old meters were dyno’s and you cranked them. Lot of guys got zapped for fun. The bad thing was if you left anything on the circuit you were testing you could blow it up - like TV’s and computers. Shooting 1000 volts into a new TV sucks.
For our large generators etc. we test them and if they are low we will have them cleaned and baked to remove moisture. Depending on the motor they can further dip it/increase the varnish to try and save it - as in Darren’s case.
The reason I asked if it was a 220/440 motor is sometimes the 440 windings are not great but the 220 combination can still work fine.
There are some cool things you can do with a megger tester. It is an annual event on the ship. I have one at home somewhere- was great for checking the condition of my well pump with out having to pull out 180 feet of pipe -
Except the test proved I had too -
Dang test!!! LOL.
You hit the wire with a voltage well above it’s used specification -
So on the ship we would megger a 600 volt line/motor at 1000 to 1500 volts. The insulation will saturate with that increased voltage (like a capacitor type event) and you can read on the meter what the insulation rating is for what you tested. Typically anything below .5 Mega ohms is cause for immediate repair. We strive for over 500 plus mega ohms.
The old meters were dyno’s and you cranked them. Lot of guys got zapped for fun. The bad thing was if you left anything on the circuit you were testing you could blow it up - like TV’s and computers. Shooting 1000 volts into a new TV sucks.
For our large generators etc. we test them and if they are low we will have them cleaned and baked to remove moisture. Depending on the motor they can further dip it/increase the varnish to try and save it - as in Darren’s case.
The reason I asked if it was a 220/440 motor is sometimes the 440 windings are not great but the 220 combination can still work fine.
There are some cool things you can do with a megger tester. It is an annual event on the ship. I have one at home somewhere- was great for checking the condition of my well pump with out having to pull out 180 feet of pipe -
Except the test proved I had too -
Dang test!!! LOL.
LOL thats awesome. I want one for my shop now.
I feel you on the well pump...mine is 220' and we had to pull it one January at -25c due to a broken wire. I though i was going to die. You can't stop and rest once you start. Whoever installed it used marettes.....
I feel you on the well pump...mine is 220' and we had to pull it one January at -25c due to a broken wire. I though i was going to die. You can't stop and rest once you start. Whoever installed it used marettes.....
Brent H
Ultra Member
Marettes!!! OMG! That is crazy insane!!!
Our well is 217’ and the pump sits at about 180 ish. It is a pain in the arch to haul out - spans a good deal of the back yard / slimy and slippery 1” ABS all the way down to a heavy freaking pump and that PITA torquer. I have my trusty 1” pipe puller made up just in case. We have the well head with the side spigot for outdoor watering. Lots of fun!
Our well is 217’ and the pump sits at about 180 ish. It is a pain in the arch to haul out - spans a good deal of the back yard / slimy and slippery 1” ABS all the way down to a heavy freaking pump and that PITA torquer. I have my trusty 1” pipe puller made up just in case. We have the well head with the side spigot for outdoor watering. Lots of fun!
200' of vertical, slimy 1" abs, full of water, instantly freezing on the way out of the hole, with a 30?ish pound pump on the end definitly has some gravity to it. I actually have to do it again this summer, to add to the casing. It's too low for the grade. I'm going to replace the pump when i do.
That is a great idea of using it for testing the well pump. I have been contemplating pulling ours replacing it as I have no idea how old it is .
Many years ago when I actually worked for a living we used a megger all the time for testing grounds and transformers.
Thanks for your insights Brent, I’m developing rules of thumb for when we should replace (600/347V operating) cables with low megger results.
Your suggestion is helpful to build upon.
Brent H
Ultra Member
@StevSmar - the marine electrical standards are under transport Canada TP127 and an excerpt:
An insulation resistance test should be made on all motors, generators and main cabling in the cold condition immediately before the machinery is put into operation and in the warm condition immediately after completion of trials and the values obtained shall be not less than 1 megohm; the insulation resistance values obtained shall be recorded and kept onboard as a permanent reference for future insulation resistance tests.
On board a ship, in a damp or wet environment we seldom see lower than 50 meg - usually it is off scale or “infinite”.
If you are getting poor readings on cables it can typically be traced to a failure of the protective sheathing letting in water, a nick in the insulation, moisture wicking through cable ends etc. a lot of times only a small length of conductor is the offending culprit and can be fixed by shortening the conductor or by drying things out and making repairs to the insulation. We have had poor readings from wires exposed to overheating (continuously) by negligence and the insulation is pooched - sad to chuck a cable out that weighs in at 15 lbs a foot- alas …..
An insulation resistance test should be made on all motors, generators and main cabling in the cold condition immediately before the machinery is put into operation and in the warm condition immediately after completion of trials and the values obtained shall be not less than 1 megohm; the insulation resistance values obtained shall be recorded and kept onboard as a permanent reference for future insulation resistance tests.
On board a ship, in a damp or wet environment we seldom see lower than 50 meg - usually it is off scale or “infinite”.
If you are getting poor readings on cables it can typically be traced to a failure of the protective sheathing letting in water, a nick in the insulation, moisture wicking through cable ends etc. a lot of times only a small length of conductor is the offending culprit and can be fixed by shortening the conductor or by drying things out and making repairs to the insulation. We have had poor readings from wires exposed to overheating (continuously) by negligence and the insulation is pooched - sad to chuck a cable out that weighs in at 15 lbs a foot- alas …..
Thanyou again Brent, that’s very helpful.
140mower
Don
Way cool man! Good luck!
Boy, that turned around pretty amazing!
You Dancin? If so, post a video so we can all laugh at you..... Er, I mean dance with you!
