Mistakes of Insulation Resistance Test | Correct Method of Megger Test

insulation resistance test or megger test is very important test to access the insulation condition of electric machines and cables. But most of the time we make common mistakes while performing megger test. In this video I have highlighted four major mistakes that should not be made. Also I show how to interpret insulation resistance test results.
#insulationresistancetest #meggertest #electricallectures

[@Krispy1011]

I have meggered hundreds of motors during my over 35 years of testing etc... if the motor or the cables have bad insulation - I always knew it within a few seconds of performing the megger test. I always megger 480v volt motors at 1,000 volts, 240 volt motors at 500 volts and 120 volt motors at 250 volts and never had an issue finding a good or bad motor or cables. Plus, we always kept records of motor testing to go back and look at trends. Trending is very important if you have lots of 250 volt DC motors in your facility.

[@electricallectures]

Yes that is true. Trending is always belpful. But you cant deny these factors also. The readings can be misleading specially on motors where insulations starts to deteriorate. Where motor insulation is already damaged then these factors are meaningless

[@Krispy1011]

If motor insulation is starting to break down you will see it in your trends as I have witness many times and then the motor is changed out for PM reasons(low megger reading). If the motor insulation is damaged you will probably be at the motor cuz it will not run and when motor is meggered you will get bad megger readings@@electricallectures

[@30mAkills]

Other 3 common mistakes:
1. Not checking the megger before using.
2. Using the megger on energised circuits!
3. Not discharging the item after testing is over.
Thanks

[@myasir1355]

greeat work done sir,

[@deddie4645]

Nice

[@bashiruosman473]

Well done. ❤

[@electricallectures]

Thabks. Stay tuned and dont forget to subscribe plz

[@aldrincallejo4548]

Tips on how to test the Motor even iti is running. "Essential Load"

[@kapitbahaychanel]

Thank you master

[@electricallectures]

Thanks. Stay tuned and dont forget to subscribe plz

[@hari_prasath_prudent]

Bro's one doubt
If need to check meggar insulation check for alternator in between ground to windings is that require to disconnect connections from main winding terminals in alternator....if checked without disconnecting avr what may occur

[@electricallectures]

No need to disconnect . You can check but remember for 400v alternator only apply 500v megger

[@evanreyes2054]

hi sir what is the difference in result if we IR test the motor applied with 500v and 1000v?

[@electricallectures]

The motor rated for 400V shall be tested with 500v megger. If you apply high voltage it may rapture the insulation

[@rafinostalgia1009]

I have megger mit310 insulation tester.when i check 250&500 volt readings showing e31 .what is the complaint is that. How correct that..

[@electricallectures]

Your instrument internal hardware error. Need service

[@HassanMajed]

Hello sir
If you can help me, I have this device showing a wrong value for the resistors, what can I check to discover the defect?

[@electricallectures]

How can you test resistance of resistors with it

[@HassanMajed]

@@electricallectures sorry sir I mean resistance not resistors
For example when I Check 1 MOhm this device showing 100 Ohm

[@raulm9847]

Can I do megger test in a hot motor?

[@electricallectures]

There is apparently no issue to apply megger to hot motor except if there is a moisture , that would be dried up when its hot and you will get good reasult but derection of moisture is evident

[@JDT738126]

Very good narration, too bad the video didn’t have a live example on how to do it properly

[@electricallectures]

Thanks for the video. It is not about hiw to do megger. It is about highlightling the mistakes which are normally ignored. And you can learn without actually doing it

[@jhunacosta6621]

Megger is a brand

[@electricallectures]

Megger is a device to test insulation resistance.

[@buttheadya]

​@@electricallecturesLMAO

[@nikolayhristov8493]

​@@electricallecturesreally 😂

[@kingofslotsmillion3263]

So I'm megging a motor a 480 v motor and reading 78.9 mega ohms to ground. Is that bad

[@electricallectures]

Perfect. No issue

[@kingofslotsmillion3263]

@@electricallectures omg ITS A LARGE 350 AMP MOTOR AND THEY BRINGING A CRANE OUT TODAY TO PULL IT. WE HAD A FIRE ON A FORGING PRESS. and there was a fire near the motor melted alot of stuff. So I figured the varnish must have been compromised. So when I was getting the 79-90 mega ohms I called it bad. On what if one Legg was .079?

[@electricallectures]

Megger value must be large for all windins

[@lhadytagupvlog]

Nice

[@electricallectures]

Thanks. Stay tuned and dont forget to subscribe plz