What does this message mean on my Metrel MI3000?

[HappyHippyDad]

Hello all..

I have been wondering what this message means for sometime, its now happened once too often and I have at last got around to taking a picture which I am posting to you guys!

I have a Metrel EasiPLUS MI 3000.

This problem occurs perhaps once in every 20 homes. When trying to take a Zs, if this message comes up then however many times I try to get a Zs at that particular point (e.g FCU or socket or lamp) I will get the same message. The reading I get is shown below, it is the squiggly line that is present in the message field that I cannot find a meaning for in the entirety of the Metrel manual? Does anyone know?



Cheers all

 

[GEOFF S]

Hi

Its possibly telling you there is too much noise on the system.

Cheers

 

[Fox]

Agreed - I've had this before as well. There is too much electrical noise on the circuit under test for the meter to calculate an accurate impedance value.

 

[DuaneMHunt1976]

Guessing its Noise, tho it looks like you have not power running in it
http://www.metrel.si/fileadmin/BAZA...02_EurotestXE_ANG_HW_3_Ver_3.1_20_750_131.pdf

 

[HappyHippyDad]

Hi

Its possibly telling you there is too much noise on the system.

Cheers

Could you expand a little on that please Geoff? Noise?

Agreed - I've had this before as well. There is too much electrical noise on the circuit under test for the meter to calculate an accurate impedance value.

As above Fox? Is there any way around this (other than taking a Ze and R1+R2) and more importantly is this more a problem with this particular Metrel? If it is I may may be inclined to purchase a different MFT, perhaps a Megger unless 'noise' is a common problem amongst all MFT's when testing for a Zs?

Guessing its Noise, tho it looks like you have not power running in it
http://www.metrel.si/fileadmin/BAZA...02_EurotestXE_ANG_HW_3_Ver_3.1_20_750_131.pdf

It does look like that Duane doesn't it!

There was power running to it, I can only assume the tester reverts to this state after this particular test result or I had switched power off after!

 

[DuaneMHunt1976]

about as close as you get to a Tooth/saw wav format
i know there is no power because it says 0 between all connections

Ive tried my MI3100 on Loop mine just has Zs and Zsrcd, tried to google it but seems your the only one in the WORLD with this problem! or who is admitting to it! guess Email Metrel!

 

[Fox]

As above Fox? Is there any way around this (other than taking a Ze and R1+R2) and more importantly is this more a problem with this particular Metrel? If it is I may may be inclined to purchase a different MFT, perhaps a Megger unless 'noise' is a common problem amongst all MFT's when testing for a Zs?

Low impedance supplies prone to electrical noise will have an affect on your loop test result and although a nuisance, it's a good thing your tester is giving you a warning. I know Megger and Fluke MFT's do a similar thing where high levels of noise are present.


Most modern test equipment likes a nice pure sine wave in order to time the start/stop period of measurement. Try disconnecting appliances and temporarily bypassing/disconnecting RCD's and electronic equipment. If this has no effect, there could be a power quality issue supplying the property in question, although fairly unlikely.

 

[Brightspark2]

I have a metrel, not that one though, but mine has started to do it a lot, it's really annoying.

Was on a fully isolated db, Site **** down, and it was still throwing it up, it does all the time now, Its a fault, I have to use different tester instead which gives the result no problem.

 

[HappyHippyDad]

I have a metrel, not that one though, but mine has started to do it a lot, it's really annoying.

Was on a fully isolated db, Site **** down, and it was still throwing it up, it does all the time now, Its a fault, I have to use different tester instead which gives the result no problem.

Interesting Brightspark.

Unfortunately I only have one MFT otherwise I would try a different tester at the same time to see if the same message is given. However as mine is intermittant and usually I do get a result I shall stick with it for now.

Thanks all for the replies.

 

[davesparks]

If you have any concerns about your test equipment you need to get it checked out.

 

[Richard Burns]

I have just had the noise signal on a Zs today, I was testing RCD protected sockets and could not get a reading, then the builder stopped using his SDS on the same socket circuit and I got a reading, I think the SDS may have had an effect.

 

[DuaneMHunt1976]

Is getting it calibrated each year.the same as maintenance... Some thing Richard said one time about the warrant and such


So there ya go, get everyone to turn off their.vibrating toys

 

[DuaneMHunt1976]

http://www.metrel.co.uk/fileadmin/B..._s__EurotestEASI_UK__Ver_1.0._20_752_165_.pdf

High electrical noise was detected during measurement. Results maybe impaired.

 

[Farmelectrics]

must admit ive had similar on my metrel m1300 but it did give me areading eventually . can someone explain what electrical noise is must admit its a new one on me

 

[DuaneMHunt1976]

Im not the best one to explain as my English is too poor,

As i see it Nothing is Perfect, that 230v AC isnt a Smooth sign wave, it picks up sounds that boost or take down in places ]
you can hear Motors on Audio, or hearing a Mobile Phone being called up via the TV Speaker.

https://en.wikipedia.org/wiki/White_noise

Networking cables being kept away from power lines as the leaker just a fraction and could change a 0 to a 1

 

[Farmelectrics]

not what i tried to copy ha ha

 

[ackbarthestar]

must admit ive had similar on my metrel m1300 but it did give me areading eventually . can someone explain what electrical noise is must admit its a new one on me

Interference is another name for electrical noise, historical forms of interference used to be high voltage sparks generated from motor distributors, or something called poor suppression. Using a Bandpass filter, that is something akin to just a capacitor to ground will do the trick. However, there might be other problems. Google bandpass filter and add in the F1 and F2 range.

 

[Richard Burns]

When you are measuring the earth fault loop impedance on a no trip setting that is using less than 15mA of current to test with the meter is attempting to use ohms law to calculate the resistance i.e R =V/I, since I is only 15mA any variation in current draw due to unstable waveforms will have a very noticeable effect on the result.
For example if the current was varying by 5mA this would be very significant.
On the high current test you tend to be using a 20-25A current (which can trip 6A MCBs) but a variation of 5mA would not be significant.

The Metrle takes a series of measurements (which is why it takes so long) to get an average reading.
If the standard deviation of the results is too great then a meaningful value cannot be obtained so the meter shows the noise signal.