Calibrating MFT

[gazdkw82]

Iv recently purchased my first MFT and will get it calibrated soon

however, I was thinking, what is actually happened to the machine to warrant regular calibrated? Is something physical moving in the machine that needs adjusting? Is it a software thing?

 

[Pete999]

Iv recently purchased my first MFT and will get it calibrated soon

however, I was thinking, what is actually happened to the machine to warrant regular calibrated? Is something physical moving in the machine that needs adjusting? Is it a software thing?

Why calibrate test equipment? from Cole-Parmer United Kingdom

 

[gazdkw82]

Thanks that was a good read

in terms of calibrating, how do I go about finding somewhere local to calibrate my MFT?

just run a Google search?

Im not actually using the machine yet for any real work purposes, I'm just using it to practice doing all the tests, would advise to still get it calibrated considering the results don't really have to be accurate?

 

[Richard Burns]

You will need your MFT calibrated before you start doing any work so that it is ready to use, however for check purposes just do a comparison check on a check box, dedicated RCD / circuit to ensure nothing odd is going on, but before you start using it for true testing get it calibrated (and remember when it was done so that the next one is not such a surprise!, or is that just me.)

Have look at similar posts for calibrators there are often questions about them.
However anyone local who can perform calibration traceable to national standards should be OK.
Wholesalers have calibration days where you can drop of the machine and pick it up at the end of the day.
The precise calibration of an MFT should take a reasonable time if it is done well, but this does not seem to happen in a lot of cases, but does not seem to cause a problem.
However if you are a stickler for correct procedure then your MFT should be stabilised to the local test environment for a day before calibration.

 

[gazdkw82]

And what test is that? Just a regular RCD trip test? What am I looking for when I do the test?

the last calibration was done a good few years ago so it way out of date

 

[telectrix]

Thanks that was a good read

in terms of calibrating, how do I go about finding somewhere local to calibrate my MFT?

just run a Google search?

Im not actually using the machine yet for any real work purposes, I'm just using it to practice doing all the tests, would advise to still get it calibrated considering the results don't really have to be accurate?

ring mike at OSCS. he will come to you at workplace or home. 07776 200146.

 

[Richard Burns]

As a check of your meter it is generally recommended that a check of consistent results is undertaken on say a monthly basis.

This involves measuring low ohms, IR, EFLI, PFC, RCD on the same test box or circuit each time and recording the results.
Then the result from last month can be compared to this month and see if there is a significant change or if there is a slow drift over several months, this ensures that you are not slowly getting more and more inaccurate over time. (a lot can happen in a year).

There are dedicated check boxes that can test all the functions of an MFT, but they are fairly costly.
Decade boxes (boxes of accurate resistors with test points) are available but still costly, check boxes tend to be a bit cheaper and have resistances for testing the MFT resistances ranges.
For the RCD, EFLI, PFC tests this can be done from a dedicated socket in your workplace that is solely for this purpose and (barring network changes outside the property) should be consistent over a year.
View attachment Check box results form 2.pdf
View attachment Check box results form 1.pdf
You could use a result sheet like either of these to record your test results and compare. (I have just had to convert them to pdf as excel files will not upload, sorry)
Your competent person scheme may also want you to do this.

 

[telectrix]

any road. my 1934 analogue voltmeter has never been calibrated since the year dot, and it still reads accurately. all it's needed over the last few years is some furniture polish on the solid oak case.

 

[telectrix]

As a check of your meter it is generally recommended that a check of consistent results is undertaken on say a monthly basis.

This involves measuring low ohms, IR, EFLI, PFC, RCD on the same test box or circuit each time and recording the results.
Then the result from last month can be compared to this month and see if there is a significant change or if there is a slow drift over several months, this ensures that you are not slowly getting more and more inaccurate over time. (a lot can happen in a year).

There are dedicated check boxes that can test all the functions of an MFT, but they are fairly costly.
Decade boxes (boxes of accurate resistors with test points) are available but still costly, check boxes tend to be a bit cheaper and have resistances for testing the MFT resistances ranges.
For the RCD, EFLI, PFC tests this can be done from a dedicated socket in your workplace that is solely for this purpose and (barring network changes outside the property) should be consistent over a year.
View attachment 32461
View attachment 32462
You could use a result sheet like either of these to record your test results and compare. (I have just had to convert them to pdf as excel files will not upload, sorry)
Your competent person scheme may also want you to do this.

or check them against a wet finger. :lol:

 

[Pete999]

Thanks that was a good read

in terms of calibrating, how do I go about finding somewhere local to calibrate my MFT?

just run a Google search?

Im not actually using the machine yet for any real work purposes, I'm just using it to practice doing all the tests, would advise to still get it calibrated considering the results don't really have to be accurate?

No Mate any or most of the Wholesalers offer a Calibration service, why not ask one of the Sponsors CEF if they can advise.

 

[gazdkw82]

There's a local company (Expert On Site Calibration Of Equipment | OSCS) they can calibrate at my house for £50 including certification.

is there anything special I need to ask for? My MFT last calibration was about 4 years ago

 

[Richard Burns]

That is the company Telectrix recommended.
Nothing special to ask for, just an annual calibration of a "make" multifunction tester that has not been calibrated recently.

 

[gazdkw82]

Thanks telectrix