VOL O-L on Megger 1720

[electricbill]

Hi all - when testing ring final continuity in a small shop the other day my Megger 1720 wouldn't carry out the test and displayed "VOL O-L" on the L and N legs (CPC was OK). I believe this message is due voltage present on the cables....MCB was off. When switching the board off at the main switch the circuit was reading open on both legs.

Obviously I have a discontinuous ring that would need investigating...but usually the meter will just read >999 and not VOL O-L.....so my question is, is the VOL O-L error due to induced current from adjacent circuits or is there likely to be something else going on here?

Many thanks - Bill

 

[Pete999]

Hi all - when testing ring final continuity in a small shop the other day my Megger 1720 wouldn't carry out the test and displayed "VOL O-L" on the L and N legs (CPC was OK). I believe this message is due voltage present on the cables....MCB was off. When switching the board off at the main switch the circuit was reading open on both legs.

Obviously I have a discontinuous ring that would need investigating...but usually the meter will just read >999 and not VOL O-L.....so my question is, is the VOL O-L error due to induced current from adjacent circuits or is there likely to be something else going on here?

Many thanks - Bill

Just checked the manual on google VOL-O-L is voltage overload

 

[electricbill]

Just checked the manual on google VOL-O-L is voltage overload

Yes - thats right...I was really more trying to ascertain the reason for it though.

 

[tony mc]

It is a safety element on your Megger which stops you testing further you will have to find out why and how much voltage is present and eliminate it before yo can continue,

You will get the same when IR testing im affraid



1

5

 

[Pete999]

Any UPs present on that RFC?

 

[electricbill]

Ah...good call, may well be - Thanks!

 

[Pete999]

Ah...good call, may well be - Thanks!

Let us know what you find

 

[electricbill]

Ah...good call, may well be - Thanks!

Actually - no it can't be as the Voltage overload fault cleared then the whole board was isolated and just showed open on those 2 legs.

 

[Pete999]

Actually - no it can't be as the Voltage overload fault cleared then the whole board was isolated and just showed open on those 2 legs.

You could have a small workstation UPs plugged insomewhere on the RFC

 

[Midwest]

Hi Bill, I've had this a few times on my 1730. I think you'll find it may be phantom/induced voltages, being sensed by your MFT, IMO. The MFT reacts to these voltages with different error messages, depending on the test being carried out, in my experience. As you've said, when you've isolated the whole installation, the MFT carries out the test.
The only way to be sure, is testing the circuit for voltage with an analogue tester, or meter not affected by phantom voltages.
I’ve found Megger technical quite helpful, to explain the error codes the MFT displays, as the manual is a bit unclear. I have the name of a particularly helpful guy, on another PC. I’ll PM you’re his details in acouple of days.