Florian, As one would suspect this is far from a simple problem and it depends on what your needs are.
The complexity of calibrating a particular piece of equipment can range from simple 'hook it up to a known source and if it is withing cal, stick a sticker on it' to a many hour/day exercise in which things like drift with time and temperature are measured and corrected. It all depends on your needs. Lets take the relatively simple HP 3468A 5.5 digit multimeter on my bench here. The manual, available online has a 20 page section on performance test and calibration. This is for a meter that measures AC volts, DC volts, resistance, AC current, DC current and not much more. I keep it calibrated by comparing it to my 3456, (which is calibrated by a commercial service) because it is my main workhorse for doing electronics construction and debuging (and the 3456 is more accurate). The 3.5 digit multimeter I keep in the garage has never been calibrated, but it's used for seeing if I have 13.8VDC and continuity in circuits in the cars and not much more. And I'm happy with both. But I answer only to me. So the question is, what are your needs and requirements? Your industry may require NIST (or other defacto standard) traceable calibration for some things. Your factory may be using 3.5digit DMMs to see if there is mains voltage on lines and not much more. Or you might be in a semiconductor plant where you have a need for agreement in the last digit of several 3758 8.5 digit meters. All about what the requirement is. Bob On Wed, Jun 20, 2018 at 3:54 PM, Florian Teply <[email protected]> wrote: > Dear fellow nuts, > > just a few days after my last post to this list my boss made me > responsible for calibration of electrical measurement equipment in our > department. As funny a coincidence that might be - I'd be pretty > surprised if he was lurking here - this brought up a few questions > where I could use some insight and comments from guys with some more > experience in that than I have (which essentially is zero). > > Now, as far as I understand, calibration at first sight is merely a > comparison between what the meter actually reads and what it is supposed > to read. As long as the difference between the two is smaller than what > the manufacturer specifies as maximum error, everything is fine, put > a new sticker to the instrument and send it back to the owner. > > Now, as usual the devil is in the details: How to establish what the > meter is supposed to read. I'd be pretty surprised if it was as easy as > taking two meters and measure the same thing, say, a voltage, > simultaneously and compare the readings. Could some of you guys shed > some more light on that? > > Background of my questions is me wondering if it would be feasible to > do the calibration in house instead of sending equipment out for > calibration. I'm not so much looking for financial savings as I doubt > we get to the point where running our own calibration would be cheaper > than contracting it out, even though we have on the order of fifty > multimeters and about as many voltage sources listed, and probably some > more sitting in some cupboards without being listed. I'm rather looking > for convenience, as it is often difficult to arrange in advance when to > calibrate what and send everything in time. With the possibility in > house we could do calibration whenever we like, and whenever equipment > is not in use, and not having to ask a commercial calibration lab to > calibrate a few dozen more or less complex devices within two weeks > maintenance break in summer. And not needing to ship equipment out > would be a plus as well as some of our guys don't like the idea to send > a few hundred kilo euros worth of equipment around just to get a fancy > new sticker on it... > > Best regards, > Florian > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://lists.febo.com/cgi- > bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
