Current Sensor / Monitor / Logger

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  • Paul_B
    Automated Home Legend
    • Jul 2006
    • 608

    Current Sensor / Monitor / Logger

    Is anyone or has anyone discovered a way to measure current drawn when a device is running?

    I am after a small device / pcb board to measure current and output an analogue signal so that I can log current /power consumption for key appliances; washing machine, dishwasher, television, etc
  • toscal
    Moderator
    • Oct 2005
    • 2061

    #2
    Re: Current Sensor / Monitor / Logger

    Try these sites

    http://www.conrad.com then look under electronics & metering - measurement systems then Environmental Analysis Devices
    They have a few power meters to choose from
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
    Renovation Spain Blog

    Comment

    • toscal
      Moderator
      • Oct 2005
      • 2061

      #3
      Re: Current Sensor / Monitor / Logger

      Finally found the sites I was originally looking for.
      If you are handy with a soldering iron then this might be worth a look;
      inductive current detection
      and also
      CR Magnetics
      CR Magnetics do all sorts of detectors and transducers for power, current and voltage.
      IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
      Renovation Spain Blog

      Comment

      • JohnEM
        Automated Home Lurker
        • Oct 2004
        • 6

        #4
        Re: Current Sensor / Monitor / Logger

        Originally posted by Paul_B
        Is anyone or has anyone discovered a way to measure current drawn when a device is running?

        I am after a small device / pcb board to measure current and output an analogue signal so that I can log current /power consumption for key appliances; washing machine, dishwasher, television, etc
        Try www.electrisave.co.uk

        (just got one and it works a treat)

        John.

        Comment

        • Paul_B
          Automated Home Legend
          • Jul 2006
          • 608

          #5
          Re: Current Sensor / Monitor / Logger

          Thanks Toscal and John,

          I am going to have a play with some of the Conrad Inductive Resistors. I'll report back on my success.

          Paul

          Comment

          • Karam
            Automated Home Legend
            • Mar 2005
            • 863

            #6
            Re: Current Sensor / Monitor / Logger

            Generally speaking you need to get a voltage signal measurement as well as the current (i.e. need instantaneous values for both), since for non resistive loads, e.g. motors, the voltage and current will not be in phase and so the power is not just current x line voltage.

            In typical electronic energy meters the current is either sensed by a current transformer (coil) wrapped around the current bearing conductor, or by placing a precision low value resistance in series with the load and measuring the small voltage drop across this. A microprocessor is then used to sample rpresentative values of current and line voltage which can then be multiplied or processed in other ways to give various measures of power.

            There may well be easier/different ways to achieve the same result, after all until recently most electricity meters used electromechanical methods.

            Another consideration is safe isolation if the measurement is to be logged by a human touchable device e.g. a PC. 8O

            Karam

            Comment

            • NicBetts
              Automated Home Lurker
              • Mar 2004
              • 1

              #7
              Electrisave and HomeSeer or similar

              I like the simplicity of the Electrisave product but want, as always, to tie it in with my HomeAutomation system.

              Does anyone know of, or can think of an easy way to integrate this or similar with a computer. Thinking of some sort of stream hitting the serial or USB port that I can then read off.

              Thoughts ???

              Comment

              • Otto-Mate
                Founder
                • Jan 2004
                • 882

                #8
                Ian Goodhew posted a message on our mailing list about this early in the week...



                M.
                Editor AutomatedHome.co.uk


                www.facebook.com/AutomatedHomeUK
                www.twitter.com/ottomate
                www.instagram.com/automatedhome/

                Comment

                • b_weijenberg
                  Automated Home Sr Member
                  • Sep 2006
                  • 54

                  #9
                  The RFXPower is able to do what you want. http://www.rfxcom.com/sensors.htm
                  It measures the real power by multiplying the measured voltage and the measured current. So even when the voltage drops the measured power is accurate. A clamp-on current transformer is used and this can be clamped around the phase wire from the main breaker to the fuse bus. Or it can be clamped around 1 wire from the wall outlet to the device.

                  It is supported by the ACRF and xAP plug-in in Homeseer.
                  See a nice implementation at http://board.homeseer.com/showthread.php?t=118165

                  The RFXCOM USB 433.92MHz X10/Oregon receiver can receive the full 48 bits RF packets from the RFXPower. This RFXCOM receiver is able to receive:
                  - Oregon Scientific 1.0, 2.1 and the latest 3.0 protocols (433.92MHz is used worldwide)
                  - "NON-US" X10 sensors and remotes
                  - Digimax
                  - RFXSensor
                  - RFXPower.
                  A second receiver can be inserted in the USB interface. This can be a 310MHz X10 receiver (for US X10 sensors) or a Visonic/VP1000 receiver or a KlikOn-KlikOff/Nexa receiver.

                  Bert

                  Comment

                  • Karam
                    Automated Home Legend
                    • Mar 2005
                    • 863

                    #10
                    Electrisave

                    Had a quick look at Electrisave product and as far as I can tell there is only a current transformer. This means that it could be relying on the (simplistic) calculation of power based on multiplying measured current by assumed RMS voltage. As I mentioned earlier this is only a good approximation for resistive loads such as incadescent lights or electric heaters.

                    Perhaps for the 'average' home power is mostly consumed by resistive loads in which case it may provide a reasonable rough guide.

                    Karam

                    Comment

                    • Paul_B
                      Automated Home Legend
                      • Jul 2006
                      • 608

                      #11
                      As I started the thread then I will add what I have found.

                      I can't find a device that will for appliance level monitoring. I have found devices that will record at the Consumer Unit for each circuit. I bought a Single Phase Kilo-watt meter that is 2-DIN and generates a pulse output for every 10WH. I then feed this into my Idratek system.



                      For me this works a treat and I already know that my kitchen draws on average 1KWH per day (incl. washing machine, dishwasher, fridge and kettle. Excl. cooker). The graph output in Idratek lets me know when the kettle comes on and how many times the dishwasher has been used in a day.

                      Comment

                      • 60milesmile
                        Automated Home Lurker
                        • Apr 2007
                        • 2

                        #12
                        Hi Paul_B,

                        I'm new to all this, but was wondering how your used the pulse output of the DIN rail meter within your system - its proberly obvious, but I'm not familiar with the Idratek system, is there a piece of kit that will acept a pulse as an input and make sence of it?

                        Cheers;

                        60.

                        Comment

                        • Paul_B
                          Automated Home Legend
                          • Jul 2006
                          • 608

                          #13
                          With Idratek I could use either their QDI or ODI units to "count" pulses. The infomration is then used in the Cortex system (software) to callibrate to a unit of use.

                          I have now gone for a DRM100S from www.metermanager.co.uk which is a 1 DIN model and pulses for each 0.5WattHours

                          Comment

                          • 60milesmile
                            Automated Home Lurker
                            • Apr 2007
                            • 2

                            #14
                            simple things!

                            Thanks for that Paul_B,

                            The thing is, all I want to do is log my household energy usage - I'm a student so can't afford any HA kit - and my land lord probably wont be very happy!

                            Does anyone know if the software bundled with the RFXPower sensor allows a log to be recorded in a database or CSV file?

                            Surly it does? doesn't it.....?

                            60.

                            PS: the IDRATEK system does look nice though!

                            Comment

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