Live circuit detection

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  • achapman
    Automated Home Jr Member
    • Jan 2006
    • 43

    Live circuit detection

    Just an observation really. One of the nice things about Idratek is that the modules give state feedback, but I was thinking that the ones with changeover relays could be improved by signalling not only which output was switched to connect to the input, but also whether the result was a live circuit. You could achieve this with the existing modules by putting a relay in series with the input, which could switch a detection circuit connected to an Idratek input. Achieving this in a fashion that would meet Electrical regulations might be rather challenging though.

    One use for this occurred to me when considering lighting switched using a traveller or multiway system. With a two-way traveller system there is no simple on position of the switch as this depends on the state of the other switch. Hence system state cannot be inferred from the switch position. If both switches' states are known, there is no problem, but if only one is known then it is not possible to say whether the light is on or off. Another example is where the Idratek power relay is fed though a switched spur (not an uncommon arrangement) where it is possible the power to the spur might be off. In both of these cases it would be helpful to know if the result of activating the relay was a live circuit or not.
  • chris_j_hunter
    Automated Home Legend
    • Dec 2007
    • 1713

    #2
    if it's lighting, maybe a light-level sensor could give useful feedback ?
    Our self-build - going further with HA...

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    • achapman
      Automated Home Jr Member
      • Jan 2006
      • 43

      #3
      Yes, that's certainly possible. My point was, though, that I didn't want to get into these workarounds of the sort that you have to use if you are using X10 devices. For example, if your room has other light sources, how do you determine if it's the one you are interested in and not a different one? What if someone moves a table lamp into the room? Direct state feedback from the device in question is always better than trying to check via an external sensor. Doing the latter potentially opens you up to a logic failure that could create a failure condition, due to some unexpected state that you failed to anticipate.

      Comment

      • chris_j_hunter
        Automated Home Legend
        • Dec 2007
        • 1713

        #4
        yep, quite agree ...

        OTOH, if (eg) a motor-valve is drawing current, it doesn't necessarily mean it's passing water ...

        not an easy one to cover !

        when we've finished our install (not many months to go), one of the things we have in-mind is to explore how best to have Cortex keep an eye & deal-with and/or flag-up high-level things that aren't going quite right ...

        we've been generous with sensors, so pattern recognition / neural nets maybe could help ...

        OTOH, response-times with things like heating can be rather slow ...
        Our self-build - going further with HA...

        Comment

        • Karam
          Automated Home Legend
          • Mar 2005
          • 863

          #5
          Originally posted by achapman View Post
          One use for this occurred to me when considering lighting switched using a traveller or multiway system. With a two-way traveller system there is no simple on position of the switch as this depends on the state of the other switch. Hence system state cannot be inferred from the switch position. If both switches' states are known, there is no problem, but if only one is known then it is not possible to say whether the light is on or off. Another example is where the Idratek power relay is fed though a switched spur (not an uncommon arrangement) where it is possible the power to the spur might be off. In both of these cases it would be helpful to know if the result of activating the relay was a live circuit or not.
          In the first example do you mean like a multiway conventional swich operation? Unless you are running IDRATEK relays in conjunction with conventional switches this should not happen, i.e you just have one relay/dimmer operating a light and then you can operate this from any number of IDRATEK connected sources with no confusion. Granted there is assumption about availability of power to one side of the relay contacts, which I think is effectively what you are saying in your second example. As you say question of how to measure it. One possibility is measuring current flow but not with a relay as you describe. On the other hand if you have access to the Neutral then a mains coil relay (or optoisolator) could be used in parallel with the switched load. In fact we did create some bespoked XRM style units for a customer some time ago which did just this. If current in series is to be used then probably an off the shelf hall effect based sensor might do the job whilst providing the isolation (assuming assembled and wired appropriately) but there are some very light loads these days so you'd have to be able to detect very low currents as well as allowing 16A through.

          Comment

          • Karam
            Automated Home Legend
            • Mar 2005
            • 863

            #6
            Chris,

            There is of course an existing 'Verifier' object in Cortex which allows you to set up some expected criteria to be checked a certain time after an event and an action taken if the criteria not met.

            Comment

            • chris_j_hunter
              Automated Home Legend
              • Dec 2007
              • 1713

              #7
              ah, magic, thanks ...
              Our self-build - going further with HA...

              Comment

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