[volt-nuts] traceable calibration

[Andreas Jahn]

> Hi Andreas,

Hello Greg

> You wrote:
>
>>Under which conditions the instruments will be adjusted
>>during calibration?
>> When missing the 1 year spec or
>>When missing the 24 hours spec?
>
> Good question! The term "calibration" means different things in different
> disciplines and application of it varies by company and product even 
> within
> a given discipline. In some disciplines, there's an expectation that the 
> lab
> will *adjust* your instrument. But I think most of the time in electrical
> metrology the lab runs a *Performance Test" but does not adjust unless a
> parameter is out of tolerance (OOT). Some paper standards and/or customers
> require the lab to adjust if a parameter's value reaches the limit of a 
> spec
> *guardband* limit. There has been much debate about this topic down 
> through
> the years within metrology organizations and paper standards writing
> committees.
>
> If you want to know how the German Keithley lab handles this topic with
> regards to Keithley 2000 calibration, you will have to ask them. Do please
> let us know what they tell you. (I'm curious too!)

In the meantime I have found the Keithley calibration page on web which
answers the questions:
http://www.keithley.com/services/calibration

So on Keithley calibration as standard procedure the instrument is
adjusted when the 70% level of the 1 year accuracy is not met.
So for the 10V range 70% of 35 ppm will give 25 ppm which
correspond approximately to the 90 day accuracy.

With best regards

Andreas