Testers failed calibration but perplexed now :-(

[plugsandsparks]

My MFT failed calibration on some insulations resistance measurements but i am a little confused. I used a different more local calibrater as i needed the least downtime but his certificate is very different from the manufacturers one that was done before (now i have had time to compare side by side)

Basically my tester has failed 4 tests (one on 500V range and three 1000V range) of these 4, 3 readings are at a different much higher resistance tests than the manufacturer used before.

The only reading that is of comparison that failed is in the 1000V range and was marginal

So if i return it to the manufacturer i can see it simply being returned without needing anything doing.

Question: do i go back to calibrater and ask why has he tested at settings different from manufacturer (and harder to be accurate test modes)
Or do i send it back to manufacturer and just get it "done" ( i think i have been anyway)

Do i carry on regardless as the areas it has failed "1000V" range is not exactly used alot (at all really)
and the one on the 500V range is nothing that would make any difference to anything an electrican needs to measure on cable - however my tester has a new sticker saying calibration due august 2013 with fail written by hand in pink..... puzzled.

What do you think guys - always used manufacturer before and it just comes back OK.... this is new territory.

 

[Knobhead]

If you’ve sent it for calibration I would expect the test house to make any adjustments to bring it in to accepted range.

I used Dowding and Mills when I was working, (the company paid).

 

[Silly Sausage]

Did they even attempt to get it within range?
As Tony says, that's the whole purpose of calibration, to bring the instrument within limits! Not just test it!

If they've attempted to calibrate it and can't, it is probably in need of repair.
Get back to your so-called calibrators.

 

[plugsandsparks]

I was open mouthed when they told me, i did say "how can it fail calibration" and i did ask say to them " I thought you just made an internal adjustment" but they said no they dont do that, but did put in fresh batteries.
Going to ring Kewtech tommorow and see what they say.
Need the tester all week, then go on hols.

 

[Silly Sausage]

I was open mouthed when they told me, i did say "how can it fail calibration" and i did ask say to them " I thought you just made an internal adjustment" but they said no they dont do that, but did put in fresh batteries. Wuppee frigging do!
Going to ring Kewtech tommorow and see what they say. Good idea.
Need the tester all week, then go on hols.

Hope you get sorted.
Let us know what Kewtech say.

 

[Swicade]

It would be more suspect if the calibration company you used also sold meter's tbh.

 

[telectrix]

methinks you have picked the wrong calibration firm.

 

[Knobhead]

P&S, for other members of the boards information what's the name of the test house you used?

 

[plugsandsparks]

Not happy about stating test house at the moment as i am slightly embarrassed about my expectations that it would come back "sorted" and i need answer to e.g.

IR on 500V - applied values were 1M, 10M, 50M, 100M, 500M and 1000M, the one which it failed on was 1000M were it read 653M.

However last calibration done by Kewtech on 500V setting was 1M, 10M and 100M

quite frankly i dont give a monkeys about anything over 100M, think they are trying to be too clever.

Its the same story on 1000V setting, applied value 1M, 10M, 100M, 500M and 1000M
readings were 1.00M, 9.88M, 93.7M (fail), 452M (fail) and 620M (fail)

I have checked the specs of the tester and its claims of accuracy and this testing house is doing it literally by the book but them why does the manufacturer not do the same and why have a tester trying to accurately measure stuff like a 1000M
FFS

Anyway will talk to Kewtech in morning and report back

 

[telectrix]

strange, because most testers have a max of either 199meg or 299 meg. anything over is a >---

 

[trev]

My Metrel reads >1999 Meg. I thought the whole point of a calibration is to make sure that the meter reads correctly within tolerances. If that means adjusting the instrument then so be it

 

[plugsandsparks]

Mines KT65 auto ranging 20/200/2000 so its actually claiming this level of accuracy.
However even last job i did was still getting >1999 on 500V and a really long cable run almost got it down to 1700M

 

[topquark]

I would be tempted to ask the "calibration company" what they would charge you to fix it. If they give you a price, then they're trying it on!! If it's capable of being fixed they should have already done it for what you've paid (unless they're own T's n C's say otherwise, but that would be unusual).

 

[ruston]

I would be tempted to ask the "calibration company" what they would charge you to fix it. If they give you a price, then they're trying it on!! If it's capable of being fixed they should have already done it for what you've paid (unless they're own T's n C's say otherwise, but that would be unusual).

Yes I agree with that , after all you have sent it for calibration not a check, you could have done that on your check box if that was the case.

 

[thekingiam]

calibrate (k l -br t ) 1. To check, adjust, or standardize a measuring instrument, usually by comparing it with an accepted model.