It's just badly worded. The "calibrator" will be simulating an RCD disconnecting after x ms, and checking that the equipment under test registers that time ± the allowed margin.
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Megger MFT 1730 Calibration?
"Unlikely" since I would have thought that it would be extremely difficult to produce a 'box' that would do that - at least, for a sensible price.
There is no problem 'checking and verifying' that a meter is displaying a sufficiently accurate disconnection time when the 'true' disconnection time (as judged by the 'tester tester') was close to, say, 30.0 ms, but creating a situation in which the true disconnection time (under the test conditions) was exactly 30.0 ms would be far from trivial.
Kind Regards, John
Have you ever seen the prices of those "boxes"?
This also makes no sense as worded
Surely the tester's job when used is to create an x mA current imbalance to test the operation of an RCD. So in calibration wouldn't you want to verify that it was producing that current, not be applying it somehow?
And if, e.g., "30mA" has a tolerance of 1.5mA, surely that means an acceptable value is 28.5 - 31.5mA, so how is 32.15mA a pass?
Surely the tester's job when used is to create an x mA current imbalance to test the operation of an RCD. So in calibration wouldn't you want to verify that it was producing that current, not be applying it somehow?
And if, e.g., "30mA" has a tolerance of 1.5mA, surely that means an acceptable value is 28.5 - 31.5mA, so how is 32.15mA a pass?
Of 30mA yes, but not of the applied 31.50mA.
It is confusing, but I assume what they are saying is that the 1.5mA tolerance is around their 'applied current' of 31.5mA (not the nominal 30 mA) - so that the result would be a 'pass' if the observed current was in the range 30.0 - 33.0 mA - hence 32.15 is a 'pass'.
Edit - too slow again!
Edit - too slow again!
The 30ms @ 30ma, it is 0.2ms from the limit. 0.2ms From limit ÷ 1.3ms Tolerance = 15% Away from limit.
It is 31.1ms this year, it was 30.9ms last year; I am fearing it is going to keep going up over the years!
Do Britannia correct in firmware for natural drift characteristics when readings get out of range?
In that case the entire document is misleadingly laid out.
You should not have 'parameter' immediately followed by 'tolerance' if the tolerance does not apply to the parameter.
You should not have 'parameter' and 'tolerance' in a table where they share a column heading if the tolerance does not apply to the parameter.
What does this mean?
Surely that function of the meter is to generate 500V in a test of insulation resistance, and indeed the next few rows of the report list what the meter registered for each of the test resistances at that voltage.
So to what was 550V applied? And how, and why? And where did the meter display a reading of 542.1V, and why?
Of course the performance of that function needs to be tested, i.e. they need to check that it does put out 500±50V, and I can see how that might get a reading on the test device of 542.1V. But in that case what is the "550V applied"?
Surely that function of the meter is to generate 500V in a test of insulation resistance, and indeed the next few rows of the report list what the meter registered for each of the test resistances at that voltage.
So to what was 550V applied? And how, and why? And where did the meter display a reading of 542.1V, and why?
Of course the performance of that function needs to be tested, i.e. they need to check that it does put out 500±50V, and I can see how that might get a reading on the test device of 542.1V. But in that case what is the "550V applied"?
All sorts of relevant questions about that report are being posed but, as is often said in such situations, if someone is interested in discovering the answers, they should ask those who (undertook the testing and) generated the report, not members of this forum (who, at best can only guess and speculate about the answers to the questions).
They just got back to me:
Good Morning Elliott,
Thanks for getting in touch.
I can confirm that your payment has been received, thank you.
With regard to your meter drifting out, I really wouldn’t worry as they are very stable machines and we have the adjustment procedures here to adjust if required.
In the years of calibrating the 17XX series testers, I’ve probably only adjusted 3 or 4, and we must of have hundreds of them through the workshop.
The adjustment is covered in the calibration price.
Best Regards,
Phil Trattles
Regards: Elliott.
Good Morning Elliott,
Thanks for getting in touch.
I can confirm that your payment has been received, thank you.
With regard to your meter drifting out, I really wouldn’t worry as they are very stable machines and we have the adjustment procedures here to adjust if required.
In the years of calibrating the 17XX series testers, I’ve probably only adjusted 3 or 4, and we must of have hundreds of them through the workshop.
The adjustment is covered in the calibration price.
Best Regards,
Phil Trattles
Regards: Elliott.