Metrel insulation testing issue

[Lestat]

I have a Metrel 17th edition multitester with a potential issue in the insulation testing mode. With no leads connected, I would expect a value of 500-900 MΩ but instead I get something around 50 MΩ.

Am I right to think there's something wrong with it?

 

[Richard Burns]

I would say that there is something wrong.
The reading without leads connected (or even with leads connected but not in contact) should be >1000MΩ.
Initially check that there is no contamination or water tracking across the leads connector point ( and the leads plug), this is the easy hope. If everything is OK there then it is probably something internal which can be much more difficult and costly to resolve.

 

[mhar]

I have a Metrel Mi3101. Testing at 500V my max IR is >1000MOhm, testing at 250the max is >200MOhms, using the easyswitch the max is >30MOhm.
Is the tester new to you? If so I would check the settings.
Can you do an IR test without the leads connected, (not loose but unplugged from the tester)? What result do you get? Could you post a photo of your Metrel screen?

 

[Deleted member 72666]

Try the settings L-PE, L-N and N-PE at separately at 500 volts as opposed to 'all' and then see what you get.

 

[Octopus]

What happens if you IR a "known" piece of cable? Are you on the "auto" setting?

 

[Midwest]

My Megger 1730 started exhibiting some strange readings on continuity, with one lead attached to an MET and then as I put the other lead near (not on or connected to) a copper pipe, its started to show a fluctuating low reading. I recall it was doing some other daft things.

After ringing Megger, it went back to them for repair.

 

[DPG]

As above - there must be a problem with it surely.

 

[Former Sponsor TM]

I have a Metrel 17th edition multitester with a potential issue in the insulation testing mode. With no leads connected, I would expect a value of 500-900 MΩ but instead I get something around 50 MΩ.

Am I right to think there's something wrong with it?

Hi - give Steve Jackson a call in our tech dept on 0113 248 99 66 option 2 - he was Metrel's service manager for many years and he'll be able to diagnose the fault for you over the phone.

 

[MJPD29]

We have 2 of these testers in work and this is a very common problem, leave it in to get repaired, we were told 1 of ours was repairable but the other was beyond it and it's o my 3 years old . They aren't very reliable overall

 

[Lestat]

Maybe I should have mentioned, it's doing 50MΩ with no leads plugged and the back of the unit off, with that plastic socket plate hanging loose. Before I took the back off, it was doing 15MΩ with no leads plugged in. So 50MΩ is actually an improvement and gives me hope the unit is not compromised, but the fault has to be traced still. I'm attaching a picture with the screen.

The way the tester works is, it has 2 wires (L and N) coming off the main board > into the ceramic fuses > then to a 1Ω resistor > and back on the main board. The external test leads connect (T-joint) just after the resistor.

The thing is, if I take the fuses off and test (all test leads unplugged of course), the meter shows 0Ω (continuity). Somehow counter-intuitive, but that's what it does. So in other words, it needs a solid continuous path to show the many MOhms. By this logic, it looks like it might be a dry or cracked solder joint somewhere, rather than a short condition.

Matthewd, do you remember what the problem was with yours?

Test-meter, thanks for the suggestion. I'll give the man a call.

 

[MJPD29]

That is the same one as we had that sadly couldn't be fixed, We had it in 2 different places and the insulation resistance was never correct it was even occasionally detecting a dead short even without lead connected and the Zs values were up the left, reading far too high and when we tested them with the working tester found they were no where near correct. They advised we sent it back to metrel as they had seen it before but for the price the boss opted to spend a little extra on a new fluke one, which I have to say has been great. Sorry for the lack of help I'm not sure what the exact problem with it was