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Thread: Sub-Meter Electricity Monitoring

  1. #41
    Automated Home Legend chris_j_hunter's Avatar
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    Kevin's point about the 8-bit implementation would seem to be a bit of a stopper (!) ... what chance a way around this, I wonder ?

  2. #42
    Automated Home Legend Karam's Avatar
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    Quote Originally Posted by Kevin View Post
    One of the issues - particularly if you had pulse outputs at every WH is that the counter that the IDRANet devices implement is only 8 bit and so has to be read and cleared by Cortex within circa 200 counts - with several metering circuits and high energy levels this would generate a lot of IDRAanet traffic. It also becomes inaccurate every time Cortex is stopped eg for updates.

    Having a 16 bit or ideally 24+ bit counter would be really nice as then the hardware count could effectively mirror the displayed count on the meter. But I know memory space is very tight in the modules.
    If you are drawing 3.6KW through each meter (16A) then I think that's a pulse a second or a packet dispatch every 3.3 minutes or so. 20 meters running at 3.6KW each (320 amps in total) and its a packet every 10 seconds. Not so elegant but would not exceed IDRANet bandwidth by any stretch - though if you are drawing that sort of power you may have a large property and maybe numerous IDRATEK modules as well . The metering function was intended for day to day indication rather than a full cumulative record - ie. so that people could see how they were using electricity in day to day tasks and get perhaps warnings and so on - rather than give them a highly accurate figure of electricity consumption over a month say.

    However if either of these issues prove to be a real problem in practice we can no doubt take necessary action relatively easily. For example dedicating an ODI to higher resolution reading and perhaps even memorising data in it over a period of time for greater cumulative accuracy. A matter of development priorities really.

  3. #43
    Automated Home Legend Karam's Avatar
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    Quote Originally Posted by Paul_B View Post
    With Alertme and Current Cost are we confident that both current and voltage is being measured to give true power? Or is it a case of derived power whereby the current is measured through a current clamp and the voltage is "assumed" to be 230vac? In the case of an inductive load this will be incorrect.
    Paul
    Taking a guess (and hopefully someone will be less lazy than me) I'd say current cost measures current only since it uses an inductive clamp, whereas Alertme should be able to measure proper power since the voltage signal will be available at the socket adapter - and low cost dedicated ICs to do all the measurements when you have access to the 'juice' are readily available. Does anyone know if the Alertme socket is the what I once saw reveiwed as the 'Plogg'? Seem to remember the latter having Zigby. Ok I'm being lazy again ...

  4. #44
    Automated Home Legend Paul_B's Avatar
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    Karam,

    If Alertme ever bother to reply to my emails then I will be in a better position to comment. If power measuring is commonly available in IC then we don't we have an Idratek module?

  5. #45
    Automated Home Legend Karam's Avatar
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    Quote Originally Posted by Paul_B View Post
    If power measuring is commonly available in IC then we don't we have an Idratek module?
    In what form?

  6. #46
    Automated Home Legend chris_j_hunter's Avatar
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    http://www.plogginternational.com/ploggproducts.html

    Plogg ... a combined smart meter plug (kWh) & data logger, especially suited for metering, monitoring, and control at the point of use ...

    Hardware ... either a stand-alone end user device, or an integrated energy reporting network or as an embedded device for incorporation into OEM products ... plug-in device, a number of international plug formats are available including Schuko, French, Swiss, NEMA 5-15 and Australian.

    The Plogg use single chip single-phase meters that integrate all the primary functional blocks required of a solid state electricity meter ... features : 8051 compatible microprocessor; independent 32-bit digital computation engine; voltage reference; temperature sensor; RAM, flash memory, real time clock; two UARTs; current sensor with option of an external split core CT 100A; 16A relay; DLL/API library

  7. #47
    Automated Home Legend chris_j_hunter's Avatar
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    Three versions :

    Bluetooth PloggBlu ... ideally suited to low density installations, where the main task is a roving or short duration, energy audit ... logged data can be collected wirelessly via a PDA (Microsoft Pocket PC enabled) or laptop and then transferred to a PC for consolidation, analysis and reporting ... this wireless version carries an embedded low power 2.4GHz ISM band transceiver ... based on Cambridge Silicon Radio's BCO4 Bluetooth chipset & provides full support for ... Bluetooth Version 2.0, including adaptive frequency hopping (AFH) ...

    PloggZgb ... the ZigBee version ... ideally suited to multiple installations where a permanent or semi-permanent fixture is intended or where the installation is in multiple sites across a wide-spread estate ... this wireless version carries an embedded low power 2.4GHz ISM band transceiver based on the Ember EM250 single chip ZigBeeTM /IEEE802.15.4 solution ...

    PloggZgb EAP ... Ethernet Access Point ... a gateway which allows access to ZigBee mesh networking modules over an industry standard Ethernet IP network ... once the IP address of the EAP has been established ... Firewalls permitting ... the EAP can be accessed from anywhere in the world ...

  8. #48
    Automated Home Legend chris_j_hunter's Avatar
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    And :

    Real time clock function allows time of use (TOU) metering information for multi-rate applications ... 64kB FRAM memory provides fast data storage for up to 5000 measured values plus associated date & time stamps ... logging interval can be set from between 1 minute & 1 month ... 50 samples of the voltage & current signals over each cycle period ... instantaneous & cumulative values ... downloaded in csv format ... cumulative kWh, period delta values for kWh, RMS voltage, RMS current, max' watts, current and voltage, reactive power, frequency & phase angle, logging date & time ...
    Last edited by chris_j_hunter; 17th January 2009 at 01:24 AM. Reason: sorry for split message - was rejected otherwise !

  9. #49
    Automated Home Legend Paul_B's Avatar
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    Quote Originally Posted by Karam View Post
    In what form?
    I mean that it would be nice if a Idratek module with the relays could measure the power usage if low-costs ICs exist. Although of course I am not an electronics person to know how you measure voltage and current at the same time.

    Paul

  10. #50
    Automated Home Legend chris_j_hunter's Avatar
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    Plogg seem to have a single IC OEM option ... so maybe we are - or rather, Karam is - just a small step away !

    (BTW, couldn't help noticing that this thread is getting way more views than any others, bar one, on the whole of AH)
    Last edited by chris_j_hunter; 17th January 2009 at 02:56 PM.

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