Pages containing 'uncertainty'

Usage of 5520 FSC for Power - Uncertainty Measurement

Hello All,

There has been a concern arise about the uncertainty in measurement using the 5520 FSC. For power measurement uncertainty, Met/Cal uses RSS of uncertainties arising from voltage, currentand power factor. These are done with "relative" uncertainties as a percentage result. 

Now, JCGM 100:2008 requires sensitivity coefficients be used in the computation of uncertainty. In power calibration, and 100V, 1A, 60Hz as example, the sensitivity coefficients are not unity. 

Defaulting to CMCs When Reported Uncertainty is Lower

Hello all,

We recently found a case where the reported uncertainty on a test via a met/cal procedure was lower than the CMC value on our scope of accreditation. While we have submitted a revision to improve our CMCs, we have to ensure that our reported uncertainties default to the CMC values if they are in fact better (less than) our CMC values. 

90 day vs 1 year accuracy

Looking for a way to change the MET/CAL default use of the 90 day ACC file to the 1 year ACC file. Has anyone done this? 

Measurement Uncertainty


why I don't have Measurement Uncertainty in the table that showing Full Results of calibration? What and where I must to set ? Please see images. Thanks for helping me.

Best and fastes way to calculate uncertainty using external tool

What is the best and fastes way to calculate uncertainty using external tool?
I don't want to use Metcal to calculate uncertainty, as my auditor don't like it.

So I want to automatize the calibration using metcal, and then calculate the uncertainty using my formulas in excel (or other tool like Matlab).

The problem is that I don't know how to do it. It has to be a fast way (as the calibration could have 50 or more results and I can't manage every results "by hand").

Setting the Exp_Unc number of Significant Digits correctly

Hi Everyone,

I've been working on getting Met/Cal to calculate measurement uncertainties using Met/Cal v7.3 sp1 and have come across a little bit of an issue.

I want to set the uncertainties to have 2 significant digits, in reading through the documentation it would seem that this is done via: VSET NSD=2

However, this doesn't work when the uncertanty calculated has leading 0's. So when the uncertainty should be 0.023, it instead becomes 0.02.

It was my understanding that the leading 0's were not supposed to be counted for purposes of significant digits.

Uncertainty and Guardbanding in MET/CAL

Use the attached documents to better understand how MET/CAL calculates uncertainty and determines when and how to guard band.   The uncertainty mechanism can be modified and customized by using the VSET/TEST FSCs.  Reference the MET/CAL Help system for details on VSET/TSET. 

MET/CAL Guardbanding (metcal_guardbanding.pdf)


What is required to obtain measurement uncertainties in my report?

MET/CAL requires certain information before it can calculate and report measurement uncertainties.  When using an Instrument FSC, the minimum information required can be found in this sample procedure for a handheld digital multimeter:

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