Thanks! I'll take a look. I generally log with LabView or direct into an Excel spreadsheet, maybe I can get an Excel VB Script to post expected times.
One of the concerns I am dealing with now is how to determine stability when there are cyclical operations going on. I am using the prescribed stability criteria and using this on the minima/maxima of the temperature variations as it moves up and down. Funny, as I sit starting at thermal data moving in this way, I think of it "porpoise-ing" up and down. All the best, Doug -Doug Douglas E Powell Laporte, Colorado USA doug...@gmail.com http://www.linkedin.com/in/dougp01 On Fri, Jan 6, 2017 at 2:10 PM, Brian O'Connell <oconne...@tamuracorp.com> wrote: > Rough pseudo code for my transformer algorithm for logging and monitoring > temperatures for normal operating conditions: > > time constant = (material ksp * mass) / (24*60) > sample interval = time constant / (mass * material kx) > breakpoint flags = false > > if sample interval < min interval > sample interval = min interval > > interrupts: > temperatures to circular buffer > log samples and windowed averages to network storage > > loop: > for each channel > verify exponential and set breakpoint flag for each channel > update thermal lag time > adjust sample interval if time constant > thermal lag/2 > find least dT/dt channel > find largest thermal lag time per ambient time per matching indices of > windowed means > if all breakpoint flags > indicate done > > Brian > > > From: Doug Powell [mailto:doug...@gmail.com] > Sent: Friday, January 06, 2017 11:11 AM > To: EMC-PSTC@LISTSERV.IEEE.ORG > Subject: Re: [PSES] Thermal equilibrium - 10% rule > > John, > > I agree with the common sense approach and use it frequently. It's always > interesting to me how I can look at a screen plot of 60 thermocouples and > in a second or two decide, "yes this is stable". I can even estimate how > much time it will take to become stable as a test nears the end (usually > about the time of a lunch break). More than once I have attempted to write > an algorithm to make the same projection and have failed every time. The > non-linearities and multiple heat sources & sinks makes this nearly > impossible. > > On a side-bar, Voltaire is quoted as saying "Common sense is not so > common", which mean he is man with similar sensibilities as myself. > > Those who know me personally have often heard me say what I consider to be > a corollary, "Common sense is usually neither.. common or sensible". > > > -Doug > > > Douglas E Powell > Laporte, Colorado USA > doug...@gmail.com > http://www.linkedin.com/in/dougp01 > > > > On Fri, Jan 6, 2017 at 11:30 AM, john Allen <john_e_al...@blueyonder.co.uk> > wrote: > Minor comment: > Having been the Secretary to a number of BSI committees many years ago, I > sympathise with Ralph's last para as the Chairmen can be even worse than > the > other Members - they "know what they know" and it can take an awful lot of > "effort" to "persuade" them that they need to "think again" - once had to > refuse to publish a Chairman's version of a new standard because it did not > meet the basic BSI guidelines for how a product standard should be written, > until I had rewritten a large part of it to make it at least reasonably > "testable" for the EMC-related requirements - a little (sometimes a lot!) > of > subject knowledge is required to set appropriate test and assessment > requirements! > > Unfortunately, nowadays, a large number of Committee Secretariats appear to > employ non-SME staff to run their committees and so they can be lead by the > nose by the Chairmen. > > FWIW, in the context of this thread, I used to use "commonsense" in > deciding > when the temperatures appeared to have stabilized - -taking into account > where the probes were located - particularly when the observed > temperatures > were substantially below the relevant Insulation Class limits. > > John E Allen > W. London, UK > > -----Original Message----- > From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] > Sent: 06 January 2017 17:20 > To: EMC-PSTC@LISTSERV.IEEE.ORG > Subject: Re: [PSES] Thermal equilibrium - 10% rule > > For what it's worth, we measure and log temperatures at 1 minute intervals > (sometimes quicker, depending on what is being tested) and graph each data > set in Excel and look at the curves. When they go flat (even with some > ripple), we call it stable. Good enough for all the agencies we work with. > And I like the term steady-state much better, but what it is called isn't > terribly important as I see it. The temperature can be stable (no further > increase observable) over a period, even if it's oscillating slightly > around > a mean value. The mean value could be the average of the last 20 or so > reading for instance. It requires some judgement. > > I empathize with John's experience about it taking "many tellings" on a > committee to get something right. I have stopped just short of the Makita > Khrushchev United Nations technique at times! > > Ralph McDiarmid > Product Compliance > Engineering > Solar Business > Schneider Electric > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to < > emc-p...@ieee.org> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher: <j.bac...@ieee.org> > David Heald: <dhe...@gmail.com> > -- Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
