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Thread: What would be the best way to monitor electric usage over 50 circuits?

  1. #41
    Moderator Kevin's Avatar
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    Quote Originally Posted by chris_j_hunter View Post
    >three values from two meters ...

    trouble is, one of the three is only the sum of the other two ... so the third is not really new, as it were ... ie: two meters, two items. not three ...
    So what were you expecting ? I think I missed the point ...

    K

  2. #42
    Moderator Kevin's Avatar
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    OK - Started running the counters now from a new day... and also had a quick stab at a shorter period over about 4 hours last night. Meter read immediately after time of the Cortex read.

    Sum of Cortex counts over period - 6484 = 6.484 KW
    (Excel imports and adds these up really easily for you)

    Meter Reading change = 40018147-40011603 = 6544 = 6.544 KW

    Which on initial observation would indicate some 60 pulses or about 1% were missed . I'll see what comes up from the 24Hr log.

    K

    (Meter uses 50ms marker pulse and 1 pulse / WHr)

  3. #43
    Moderator Kevin's Avatar
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    ok 24 Hours...

    Cortex count 29192
    Meter Count 40047360-40018147=29213
    Difference = 21 = .07% which I think is pretty good.

    The last digit is not displayed and the penultimate figure changes about once every 10 secs so that could easily be a reading error as I have to guesstimate when Cortex takes its reading. So I think I'm fairly confident that the QRH sampling period on the inputs is inside of 50ms - and it's not missing any :-) Good stuff.

    Now to try the ODI ...

    K

  4. #44
    Moderator Gumby's Avatar
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    Good stuff Kevin!
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  5. #45
    Automated Home Legend Paul_B's Avatar
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    Kevin,

    Interesting observation thanks for the efforts and feedback.

    Paul

  6. #46
    Automated Home Sr Member ludditeal's Avatar
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    Maybe old news or already discussed but someone is flogging single din 50 Amp meters with pulsed output for £12.95 + £3pp on E-bay.
    See item 200372094031

    Regards
    Allan

  7. #47
    Moderator Gumby's Avatar
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    There is also a module from JWInstruments at this kind of price.

    However, there seems to be quite a few Chinese clones floating about and it's difficult to know about quality. There have been some horror stories of counterfeit MCBs with no actual breaker mechanism inside them!
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  8. #48
    Automated Home Jr Member RichardC's Avatar
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    Recently purchased two 1 unit kWh meters from OCS GmbH

    Their English website is:

    http://www.my-messgeraet.com/jtlshop...=475&lang=eng&

    These will be connected to my soon to be installed Idratek system.

    16.99 Euro each.

    Search for ART-474-200828 to find them.

    They look ok, I hope that they are not too dodgy, I will be installing them over the next week and will see how they behave.

    The postage cost was almost the cost of one of the meters. Plus they do charge for Paypal.

    If anyone is interested in combining orders, if this is of interest, then please let me know. They are willing to give discount on orders of 10 or more and I will need just more than 10 to complete the installation in my CU. Plus if I have more time I can transfer the money to a friend in Germany who can transfer the money and not incur the Paypal charge.

  9. #49
    Moderator Gumby's Avatar
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    You might want to put a post in the bulk buy forum as well. The last time I don't think there was any extra interest, but you never know.
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  10. #50
    Automated Home Legend chris_j_hunter's Avatar
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    might be of interest ... latest issue of Which? magazine reviews seven energy meters & reckons accuracy varies (up or down) quite a lot with load & between devices, best within 0.5% & worst within 12.5% ... can handle one to four tariffs, according to device, and only four of them can be connected to a PC ... prices within the range 25 to 50GBP ... Current Cost, a couple of Owls, a couple of Eco-Eyes, & a couple of Efergys ...
    Last edited by chris_j_hunter; 26th September 2009 at 09:40 AM.

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