Sub-Meter Electricity Monitoring

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  • John Winter
    Automated Home Sr Member
    • Dec 2007
    • 56

    #16
    Sorry for hijacking the thread somewhat but thanks for that! I think a trip to Maplins at the weekend is on the cards.

    Jamie - would it not be much simpler to use a pressure mat?



    Cheers
    --------------------------

    www.nodeone.blogspot.com

    Comment

    • KirasHome
      Automated Home Jr Member
      • Oct 2006
      • 37

      #17
      Originally posted by John Winter View Post
      Jamie - would it not be much simpler to use a pressure mat?
      It'd probably work on the stairs but the downstairs is all hard flooring so nowhere to hide the mats :-( Hence the thought about a beam to create a virtual doorway.

      Jamie

      Comment

      • Karam
        Automated Home Legend
        • Mar 2005
        • 863

        #18
        Originally posted by John Winter View Post
        I know the thread's about sub meter monitoring - but how would one go about monitoring entire usage? My thought was to physically connect some sort of photodiode arrangement to the front of the led flashing in my meter, and then count pulses from that. Or am I missing something obvious?
        I think a single photo-transistor tied straight across the digital input terminals via a screened cable might be able to do the job simplty and cheaply but I haven't got one on hand to try and am too lazy to try and guess irradiance level from the meter LED, but you need to get enough light to get ~ 0.6mA through transistor to detect an ON LED. Obviously it also has to get dark enough when LED is off. Go for an NPN one which has a an optical rather than IR spectral response (though usually the response will spread to optical ranges with less sensitivity). To reduce effects of ambient lighting and improve contrast shroud the viewing window with an externally dark tube so transistor can just see what's infront of it. Even better if tube goes all the way to meter LED.

        Karam
        IDRATEK LTD

        Comment

        • Karam
          Automated Home Legend
          • Mar 2005
          • 863

          #19
          Light barrier

          A light barrier or retroflective sensor such as the Sharp (GP2D12?) may well help in this situation. Certainly Cortex v23 has an object representation for such a sensor (for connection to a digital input object). I think the results will depend on the detection patterns for such sensors but also what you want to achieve: We are aware of the need to consider open plan spaces but it also comes down to what type of automation might be required in such spaces even if you could zone the presence accurately. For example would you want lighting to behave as if each zone were a different room? Also how to deal with light level spillover, and so on. So its partly about sensing (and positioning of such) and partly about desired behaviours.

          Karam
          IDRATEK LTD

          Comment

          • Karam
            Automated Home Legend
            • Mar 2005
            • 863

            #20
            Pulse counting

            Originally posted by chris_j_hunter View Post
            AH also had a thread on this maybe a year ago ... inconclusive, though, IIRC ...

            presumably pulse-counting doesn't tie Cortex up - or does it ??
            Just so that you get this from the horse's mouth :-) :

            Some (but not all) modules with digital inputs have a pulse count feature. As others have suggested, this means the module counts pulses within a certain time frame and only then sends the data to Cortex. This avoids the network being hogged by a packet every pulse - though let me tell you that one of our Polish installations actually tied the output of an anemometer to a non pulse count digital input and still happily ran their network alongside several pulses a second on a windy day (NOT RECOMMENDED). The counting time frame is a settable parameter and the value chosen gives a balance between network hogging and rate of information update. For electricity metering it is typically set to 1 minute. And whilst on this subject, when you choose a meter make sure you look carefully at the resolution (how many pulses per Whr) since it obviously determines the resolution with which Cortex can estimate consumption rate (as opposed to consumption).

            Modules which presently have Pulse count feature on digital inputs are: QRI, QRH, ODI, DIO (newer variants of latter two). If in doubt ask before assuming :-)

            Karam
            IDRATEK LTD

            Comment

            • Paul_B
              Automated Home Legend
              • Jul 2006
              • 608

              #21
              Karam,

              On the subject of the ODI has the module been "improved" to allow more 0V connections? I believe the one I bought originally has just one terminal for 0V?

              Paul

              Comment

              • Paul_B
                Automated Home Legend
                • Jul 2006
                • 608

                #22
                For anyone monitoring this thread I have had a further email from a previous supplier offering a bulk discount for 10 or more ADM1TE's. The unit price is £18 which I believe is very good and I think I will be ordering some shortly. If anyone else is interested let me know.

                Paul

                Comment

                • Karam
                  Automated Home Legend
                  • Mar 2005
                  • 863

                  #23
                  ODI module

                  Originally posted by Paul_B View Post
                  Karam,

                  On the subject of the ODI has the module been "improved" to allow more 0V connections? I believe the one I bought originally has just one terminal for 0V?

                  Paul
                  Yes there are now 4 0V terminals.

                  Comment

                  • KirasHome
                    Automated Home Jr Member
                    • Oct 2006
                    • 37

                    #24
                    Originally posted by Paul_B View Post
                    For anyone monitoring this thread I have had a further email from a previous supplier offering a bulk discount for 10 or more ADM1TE's. The unit price is £18 which I believe is very good and I think I will be ordering some shortly. If anyone else is interested let me know.
                    Paul,

                    Fairly dumb question, but I can't work it out from the spec sheet - Do you know what the maximum ampage these things can take? ie can you use them to monitor a ring main with a 32A fuse? Thanks, Jamie.

                    Comment

                    • Paul_B
                      Automated Home Legend
                      • Jul 2006
                      • 608

                      #25
                      Jamie,

                      From the Tech Sheet I have been sent for the ADM1TE it shows a maximum of 30A.

                      Paul
                      Attached Files

                      Comment

                      • Gumby
                        Moderator
                        • May 2004
                        • 437

                        #26
                        I'm a bit nervous of 30A rating, surely needs to be 32A to match typical ring breaker ? I thought that one of the suppliers I looked at for DRM100S was now stating a 32A rating and the Carlo Gavazzi ones were also (I think) 32A.

                        I also found: http://cgi.ebay.co.uk/DIGITAL-WATTME...ayphotohosting on eBay and their other product http://cgi.ebay.co.uk/WATTMETER-ENER...sid=p1638.m118 which is a £1 cheaper for mechanical counter. Be nice to find an even cheaper version with no counter ! Disadvantage of these folks are that the T's & C's a in German and of course no experience with the units.
                        ----------------------
                        www.gumbrell.com

                        Comment

                        • John Winter
                          Automated Home Sr Member
                          • Dec 2007
                          • 56

                          #27
                          Well,
                          I've finally got around to playing with photodiodes and digital inputs - and FYI Karam's theory works - direct connection of a photodiode to the inputs and shining an LED on it results in a change of state in Cortex. Only problem is now, I had an external LTH lined up to do the pulse counting and reading back through the thread it appears LTH's are not capable of sending packets with pulses counted.

                          Karam - can I perhaps reflash the LTH to allow for pulse counting? How did the anemometer example work? Do I have to put in my next order for more parts? ;-)

                          John
                          --------------------------

                          www.nodeone.blogspot.com

                          Comment

                          • Karam
                            Automated Home Legend
                            • Mar 2005
                            • 863

                            #28
                            We are considering introducing the pulse counting feature to the LTH, PLH and the like (higher integration small modules). In fact some firmware exists but is awaiting test. If it works out ok then it would be just a simple matter of uploading to your existing module in situ using the Cortex firmware loader. I can't give you an exact ETA since to some extent it depends on whether we encounter any problems along the way, but the LTH will probably be one of the earlier ones.

                            Comment

                            • chris_j_hunter
                              Automated Home Legend
                              • Dec 2007
                              • 1713

                              #29
                              the more pulse-counting the better, please ... even better if it's got some flexibility, to allow fairly crude pulses (eg: simple photo-diode sensing of things) ... things like pulse-counting being best handled locally, of course, for reliability & minimum network tie-up !
                              Our self-build - going further with HA...

                              Comment

                              • Kevin
                                Moderator
                                • Jan 2004
                                • 558

                                #30
                                For me having the pulse counting on the QLD would be most useful. My main application for pulse counting is electricity consumption so it seems logical to provide these inputs on DIN modules that reside within the consumer unit - and the QLD has eight such inputs. I do use the QRH's 4 inputs.

                                Also - it seems a missed opportunity that the mains powered modules (QLH) don't supply the IDRANet power... Is there any way of having dual power supplies onto IDRAnet - such that one is redundant ? Maybe I could do this via a couple of diodes and a slightly raised PSU voltage ?

                                K

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