Discuss megger 1552 sine wave symbol in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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maudy

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Don't know if any one can help here. Today whilst doing a Zs test my megger produced a weird symbol that looked a bit like a sine wave with a vertical line dissecting it at the top. It have the correct Zs result at the same time. But id never seen the symbol before
Can't find anything about it in the instruction manual.
 

topquark

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Probably the symbol for "noise on the line" whilst sampling.

Edit: the upshot being is you can't trust the reading (if obtained).
 

telectrix

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i'm not sure, but i would agree with topquark. dammn, that'as twice in a week. LOL. :13:
 
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maudy

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It was in a school, the reading was on a ring and was exactly what I was expecting. Just that this symbol came up and earlier that day, on a different circuit, on a different board (but in the same building) the fuse went in my meter. Coincidence maybe?

The wiring is pretty old school, as is the protection lots puff beneath. Most of the boards in the building are isolated -10 or so.
 
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maudy

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It was in a school, the reading was on a ring and was exactly what I was expecting. Just that this symbol came up and earlier that day, on a different circuit, on a different board (but in the same building) the fuse went in my meter. Coincidence maybe?

The wiring is pretty old school, as is the protection lots puff beneath. Most of the boards in the building are isolated -10 or so.
Sorry - predictive text went mad on me then - i meant to say lots of bs88 fuses - not lots of puff beneath !
 

JD6400

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If i remember correctly , this is what my megger used to show when it went up s""t creek ?
Each time was followed by a rather expensive repair and get this ! The need to pay for a recalibration as megger would not do it at the same time as the repair ???
It happened 3 times in one year about 5 years ago and thats when i went for a top line fluke and touch wood to date !!!
 

SPARTYKUS

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Had my 1552 for over 4 years. It has displayed that symbol maybe 3 times.

It did not go tits up immediately after.


It would be nice if a megger chap gave a thorough detailed explanation of what this symbol means?
 

JD6400

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Had my 1552 for over 4 years. It has displayed that symbol maybe 3 times.

It did not go tits up immediately after.


It would be nice if a megger chap gave a thorough detailed explanation of what this symbol means?
It may of been another symbol that used to appear , it has been 5 years since i have used a megger !
It should still be in the stores where it got placed in disgust , i suppose i should send it off again and get it sorted as a spare .
 
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maudy

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Had my 1552 for over 4 years. It has displayed that symbol maybe 3 times.

It did not go tits up immediately after.


It would be nice if a megger chap gave a thorough detailed explanation of what this symbol means?
Yea right, it must be a feature of the model. Whatever it is trying to tell us.
 

telectrix

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It may of been another symbol that used to appear , it has been 5 years since i have used a megger !
It should still be in the stores where it got placed in disgust , i suppose i should send it off again and get it sorted as a spare .
i'll buy it if the price is right, i love megger gear.
 

JD6400

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i'll buy it if the price is right, i love megger gear.
Off on holiday in the morn for a week , if i remember i will have a look for it when i go back down to Bucks and i am at the stores again .
It will probably around the 5th Sept , so feel free to pm me and remind me around then .
 

telectrix

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dp, i'm 65. how in hell do you expect me to remember as far away as after tomorrow?
 

JD6400

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For that little gem tel , i will actually now go and write it in me dairy . Thanks for that one , made me chuckle !
 

telectrix

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actually, after tomorrow was being optimistic. i'm lucky to remember after the next pint.
 
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MarkieSparkie

Had my 1552 for over 4 years. It has displayed that symbol maybe 3 times.

It did not go tits up immediately after.


It would be nice if a megger chap gave a thorough detailed explanation of what this symbol means?
The noise warning symbol is a sine-wave with a spike on the positive half cycle, seen at the top of the display just right of centre on an Megger MFT 15xx.

The noise warning symbol on a Megger MFT 15xx, 17xx or 18xx is very rare event, due to the multi-pulse, noise cancellation measurement method employed. It is because of this patented technique that the Megger MFTs gets unfair criticism from users of other MFTs (Fluke devotees in particular) for it's apparently slow "No-trip" test, however, Megger users get the last laugh because they very rarely have their test inhibited by a noise error whereas Fluke users see their equivalent, Error 5, fairly regularly even in the domestic environment. Most Megger users reckon on it occurring about once a year, maybe a few more if you do lot of industrial work, and usually on a No-Trip loop test.

The noise warning symbol is displayed when there is excessive noise on the supply. Noise or transients on the supply voltage can effect the accuracy of the loop measurement during the test and introduce an error in the reading. The noise or transient on the supply voltage are usually caused by active appliances or equipment on the supply, the source usually this internal to the installation, but equally may be caused by an external source. Internal sources can usually be isolated (switched OFF) eg. automatically switched loads and motor controllers, however, when external sources are the cause it may require testing at a different time of day to avoid the active period, during their lunch hour or after normal working hours eg. A garage down the road maybe using welding equipment or the Vets /Doctors surgery using X-ray equipment.

If the noise warning symbol is displayed the reading should be treated as in-accurate and the test repeated, usually a second test is all that is required to get a reliable reading. If the noise symbol continually appears on repeated test the cause should be investigated.
[FONT=&amp]In an industrial environment where continuous production must be maintained and the noise source cannot be isolated, often the only thing you can do in the short-term is to take a series of readings and record the average value to minimise the error.

[/FONT]
 
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MarkieSparkie

If i remember correctly , this is what my megger used to show when it went up s""t creek ?
Each time was followed by a rather expensive repair and get this ! The need to pay for a recalibration as megger would not do it at the same time as the repair ???
It happened 3 times in one year about 5 years ago and thats when i went for a top line fluke and touch wood to date !!!
This type of behaviour is typical of a faulty Megger MFT continually displaying the hot warning symbol, when Hi-current loop testing, despite ensuring the MFT has cooled down between tests. Usually caused by a loop load that has reduced in value outside the manufactured tolerance and is being 'cooked'.
The hot warning symbol is a 'thermometer' seen at the top of the display on the far right hand side, on a Megger MFT15xx.
Because the repair of this type of fault requires the replacement of a number of components parts the instrument inevitably requires adjustment and re-calibration to ensure its intended accuracy is brought within the manufacturer's original specification.
 
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maudy

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Had my 1552 for over 4 years. It has displayed that symbol maybe 3 times.

It did not go tits up immediately after.


It would be nice if a megger chap gave a thorough detailed explanation of what this symbol means?

Thanks Markie
Exactly what I wanted to know
 

JD6400

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Hi Telectrix , i know it has taken about 8 months but here it is !
It has been in a flight case on a shelf in the stores for the last 6 years or so after it played up last time .
 
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