New MFT - opinions

[pirate]

We will be swapping out battery packs in the next decade, for sure. It's here already for some vehicles, and the rate of progress is climbing

 

[NDG Elecs]

Continuity tests shouldn't show negative results, you can't have negative continuity!

I don't know what tester you use Dave so you may not be grasping what I am saying. Maybe my wording could have been better.
With the Megger 1500's you could null the leads and get 0.0 ohms (obviously if they are nulled!), then you could take the probes apart and if you then touched them together again and got slightly better contact the nulled result would show as -0.2 or whatever.
With the 1700 series if you did the same as above the screen will only state <0.0 ohms....<0.0 is not a helpful value to man nor beast, as it could be -1.8 or whatever..it's the not knowing that kills me!!

Obviously on a length of copper you can't get a negative continuity value, but the nulling process is a baseline to account for the resistance in the test leads and MFTs internals. The 1500 series approach was more informative and useful..

 

[davesparks]

Displaying the less than symbol, a negative value or just an error message would all achieve the same thing, it alerts you to the fact that the nulling of the leads is wrong.

Whether the null is off by 10ohm or 0.1ohm doesn't really matter as it is wrong whatever and needs to be addressed.

 

[NDG Elecs]

Displaying the less than symbol, a negative value or just an error message would all achieve the same thing, it alerts you to the fact that the nulling of the leads is wrong.

Whether the null is off by 10ohm or 0.1ohm doesn't really matter as it is wrong whatever and needs to be addressed.

Predictable answer Dave with all due respect. In the real world with both Megger testers I have had, both have had a tendency to drift marginally from the original 0.0 benchline.

For whatever reasons I often find nulling leads repeatedly over a short duration can result in differences that usually range no more than 0.08 ohms. This is not a critical issue in my view for the work I do. The 1500 series displayed a tangible baseline value that could be deducted as and when necessary. The 1700s do not.

Maybe other brands of tester have better, more stable low ohm testing. I would be interested to know.

 

[static zap]

nulling leads repeatedly over a short duration can result in differences that usually range no more than 0.08 ohms.

My antiquated Fluke 1651B has none of these below 0 warnings , but I created a 0.07 Ohm confirm "0" ...
If it reads less than 0.03 I get clues of this 0.08 wander !
(Low ohms with pointed probes -is very much about surface hardness / cleanliness )

 

[Sparks82]

I’ve had the megger 1741 for just over a year I like it except for one problem.
I’ve just had a fuse blow and the circuit board damaged when carrying out 3lead low trip zs.
This is the third time it’s happened already sent it back to megger twice for repair and only used it a few times after getting it back. Anyone else had this problem?

 

[static zap]

when carrying out 3lead low trip zs.

@Sparks82
If you don't mind me asking are you doing this in a Domestic or Industrial situation ?
(Lowest readings I've seen yet ,a dedicated kitchen RFC near CU / domestic !)... Well done Kev ...

 

[SparkySy]

I haven't heard of that problem before but am interested having just yesterday bit the bullet and ordered the 1741+

 

[Sparks82]

Mostly domestic, when ever it’s happened it’s just been in a regular house!!

 

[Teddy Lop]

Used robins on the electric board. Forum rules probably prevent my expressing the depth of my feelings on the insulation tester, but after a row with our tool guy (a nepotism benefitting slob who was about as useful as ---- on a bull) I can only conclude gloucester is plagued by floating pockets of low resistance air.. Had a megger CM500 for years (original MFT?) which was a great tool, but the rotary selector got a bit iffy and meggers attitude with their enormous "standard repair fee" was that I should bin it and buy a new one which annoyed me so much for what I felt was repairable, I did and bought a metrel, £1k jobbie. 3 (theft) metrels later, 3rd was playing up at sub 3 years old, metrels 2 week turnaround plus rental added up to so much I just bought the cheap £500 martindale for about the same. Never really got on with it, supplied croc clips were thrown in the trash on day 1 and after a couple of years it got to the point I didn't trust what it was telling despite calibration. And thats no good for anything let alone fault finding, which I find myself doing much of. So I went back to megger and just accepted we live in the use-it-and-bin-it age, once you do its far and away the best instrument I've used.

I like what the guy above said about password protection though - really annoys me with such a specialised, serialised piece of kit that requires calibration through limited operators that stolen kit cant be traced.

 

[Gavin John Hyde]

I thought about the metrel all singing all dancing one with the EV charger test sequence but kewtech have an adaptor or bit of kit in the pipeline for testing them so will keep the trusty kt64dl for now.

 

[Mpe123]

Does anyone know if it would be possible for megger to upgrade all the 1700 series to carry out the 6mA RCD test, or if there is a hardware issue that restricts it to the 1741 only?

 

[HappyHippyDad]

I have one, I love it. Good bits (not saying other manufacturers don't do these things...) :

- 2 lead RCD test. No need to faff around with a neutral connection (common on all Meggers)

- Use the same 2 leads (red and green) for Ze, PEFC, and PSCC (on single phase), on the same setting: I don't bother using the separate "L-L" setting on the dial and plugging in the blue lead to measure PSCC on single phase, I just use the "L-E" setting (on "2Hi") and put the green lead on N

- Quicker, and possibly and more accurate low current Zs than other Meggers, I like the confidence indicator

- 100V IR for when you're fairly confident, but not totally confident, that there's nothing plugged in. Useless for test results, but fantastic for verifying that nothing's plugged in

- I like the long thin pointy probes, for getting in some tight spots

- Bag is great for carrying all my testing bits (jump leads, R2 adapter, lightmates etc), over-shoulder strap means I can carry my toolbox in one hand and my little ladders in the other

- in "3Lo" Zs mode, you can tell it there are Type B RCDs in play (long press on <-> ). Even if there aren't, and it's just a tetchy Type AC RCD (or maybe a lot of inherent leakage current), it's sometimes useful for getting a Zs result without using The Alternative Method (or, when you really, really don't want to trip an RCD!)

Negatives (common to all Meggers, I think):

- It's far too easy to "un-null" your leads when on continuity setting. Pressing either of the test buttons - which is very easy to do, there's one on each side and just knocking one will do it - will remove the saved null setting. A right pain in the **** if you're the other end of a wander lead! So quite often I either turn it off, or just put it on a different setting, if I'm carrying it around on my neck

- Would be nicer if the backlight light stayed on a bit longer

- Usual Megger lead incompatibility with most third party bits and bobs, so I have a couple of cheap Kewtech leads to connecting to wander lead, lightmates, R2 socket etc.

Do you use the kewtech leads with the megger Steve? Any particular ones? Link please ?

 

[Gavin John Hyde]

I am holding out for the new kewtech one in early 2021 as it will be able to do all the ev charger tests i need. aint cheap though at a rumoured £1300

 

[happysteve]

Do you use the kewtech leads with the megger Steve? Any particular ones? Link please ?

A basic set of 2 leads is all you really need, this one will do: Kewtech ACC020S Test Leads - https://www.screwfix.com/p/kewtech-acc020s-test-leads/28760

This 3-lead set is more versatile, though: Kewtech ACC016E Test Leads - https://www.screwfix.com/p/kewtech-acc016e-test-leads/72941