Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: Electricity Monitoring - Which Photodiode?

  1. #1
    Automated Home Sr Member cliffwright's Avatar
    Join Date
    Mar 2007
    Posts
    74

    Default Electricity Monitoring - Which Photodiode?

    Hi Folks,

    Just reading the Gumbrell blog about power monitoring, I have a few questions;

    1) can someone point me in the direction of which photodiode I need to achieve the same electricity meter monitoring as described here?

    2) My electric meter is outside and I'm planning on utilising the digital input on an SLD module that is under my stairs (so about 6-10 meters between the 2 as the cable runs); Are there any issues of cable length to consider? Is there a specific cable type I should use? Was planning on using a couple of joined pairs of a Cat5 run . . .

    3) Is there anything else I need to consider given I'm using the digital input of an SLD module rather than a dedicated ODI module?

    Thanks folks

    Cliff

  2. #2
    Automated Home Legend Karam's Avatar
    Join Date
    Mar 2005
    Posts
    822

    Default

    1) Probably David is best to advise you on what he knows works, but if you are looking at a pulsing LED I would imagine a phototransistor such as SFH310 might do the job. The 'when lit' current needs to be >1mA (which of course depends on the intensity of the light source).

    2) Not ideal length but should work. The main problem is potential for noise pickup. Shielded cable would be best with shield attached to IDRANet shield, if used, at the module connector or failing that to 0V at the module digital input. Otherwise if just using CAT5 cable then use a twisted pair not wires from separate pairs. You may additionally need to bolster the capacitive filtering at the digital input eg. 1uF between input and ground but don't go crazy as the pulses are probably quite short.

    3) Unfortunately the dimmer modules don't support pulse counting on their digital inputs so you'll have to try and use one on another module such as PLH or DRB

  3. #3
    Automated Home Sr Member cliffwright's Avatar
    Join Date
    Mar 2007
    Posts
    74

    Default

    Quote Originally Posted by Karam View Post
    1) Probably David is best to advise you on what he knows works, but if you are looking at a pulsing LED I would imagine a phototransistor such as SFH310 might do the job. The 'when lit' current needs to be >1mA (which of course depends on the intensity of the light source).

    2) Not ideal length but should work. The main problem is potential for noise pickup. Shielded cable would be best with shield attached to IDRANet shield, if used, at the module connector or failing that to 0V at the module digital input. Otherwise if just using CAT5 cable then use a twisted pair not wires from separate pairs. You may additionally need to bolster the capacitive filtering at the digital input eg. 1uF between input and ground but don't go crazy as the pulses are probably quite short.

    3) Unfortunately the dimmer modules don't support pulse counting on their digital inputs so you'll have to try and use one on another module such as PLH or DRB
    Thanks Karam

    I'll be using a lenght of C-Bus cable so hopefully won't pickup too much in the way of noise . . . we'll see I guess . . .

    David - would appreciate the benefits of your experience if you're around?

  4. #4
    Moderator Gumby's Avatar
    Join Date
    May 2004
    Location
    Gloucestershire
    Posts
    437

    Default

    Sorry - was on holiday in a hole with sporadic connectivity...

    err.. well, I *should* have carefully selected the correct device to use based on my knowledge of electronics and examining the characteristics of the ODI and guessing the output of the meter LED, but what I actually did is wandered into Maplin and bought the only visible light photodiode available ... can't remember the model number I'm afraid.

    I put an ODI right next to the meter to avoid long cable runs. So you could extend your Idranet to the meter instead of trying to avoid noise pickup in photodiode cabling. Partly because I had a spare ODI... and partly because it started out as a complete experiment and I didn't want to worry about pickup and extra filters and screening etc.
    ----------------------
    www.gumbrell.com

  5. #5
    Automated Home Sr Member cliffwright's Avatar
    Join Date
    Mar 2007
    Posts
    74

    Default

    Quote Originally Posted by Gumby View Post
    Sorry - was on holiday in a hole with sporadic connectivity...

    err.. well, I *should* have carefully selected the correct device to use based on my knowledge of electronics and examining the characteristics of the ODI and guessing the output of the meter LED, but what I actually did is wandered into Maplin and bought the only visible light photodiode available ... can't remember the model number I'm afraid.
    Cheers - appreciate the help; that sounds like my kind of approach to electronics (but possibly with less electronics knowledge to start with)

    By the same approach, I'm guessing this might do the job then?

    http://www.maplin.co.uk/sfh2030-sili...otodiode--2242

    Quote Originally Posted by Gumby View Post
    I put an ODI right next to the meter to avoid long cable runs. So you could extend your Idranet to the meter instead of trying to avoid noise pickup in photodiode cabling. Partly because I had a spare ODI... and partly because it started out as a complete experiment and I didn't want to worry about pickup and extra filters and screening etc.
    My 'leccy meter is outside in a location that is pretty stand-alone in terms of Idranet needs so for me to 'site a dedicated module near it it would more or less have to be for the sole and total purpose of meter reading which, like you, this is a little experiment (a) to teach me a bit more about Cortex's uses and (b) see if once I've captured this data it's actually of any tangible use.

    Given this, I was hoping to make use of a 'spare' digital input rather than fork out ~50 for a module like an ODI.

    Might give the 'long cable run' approach a go first to see what happens and then think about how I could 'work in' a dedicated unit more usefully.

  6. #6
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,676

    Default

    checking our new digital meter (*) just now, which we hope shortly to read in a similar way, I see there are two LEDs behind a small window that's marked 1000 impulses per kWh (ie: max. pulse rate could be 100 x 250 / 1000 = 25Hz) ... hmm, wonder which of the two LEDs we should read via the photodiode ??

    we're still wiring the house, including for Idranet (using appropriately orange Cat-5e FTP - third box just started) - and (thanks to this thread) it looks now like we should be saving any off-cuts for sensor spurs !

    (*) a Landys + Gyr type 5235A / 20mA-100A / 2W 230W / CI 2 2009 - with a bar-code & an LCD digital display, as well as the two LEDs


    PS: have just found the datasheet, and it looks like the B version of our meter would have terminals for the pulse output :

    http://www.landisgyr.com/za/apps/pro...fication11.pdf

    unfortunately, that's not the one we have, but it's interesting that some meters out there could have terminals for this function & so not need a photo-diode to be added ...

    OTOH, it also looks like the supposed two LEDs are actually one LED plus a photo-diode for two-way comm's using this protocol :

    http://en.wikipedia.org/wiki/IEC_62056

    ie: if we add a photo-diode, the utility company would be prevented from reading our meter with a hand-held device ...

    hmm, that seems to put a spanner in the works !
    Last edited by chris_j_hunter; 28th June 2011 at 08:49 AM.

  7. #7
    Automated Home Legend Karam's Avatar
    Join Date
    Mar 2005
    Posts
    822

    Default

    Quote Originally Posted by cliffwright View Post
    By the same approach, I'm guessing this might do the job then?

    http://www.maplin.co.uk/sfh2030-sili...otodiode--2242
    I don't think the photodiode will pass sufficient current when illuminated. A photo transistor would be more sensitive and fast enough for this application.

  8. #8
    Automated Home Legend Paul_B's Avatar
    Join Date
    Jul 2006
    Location
    Eastbourne, UK
    Posts
    605

    Default

    Hi all rather than start a new thread I thought I should update an old.

    For those with an electricity meter that produces a LED "blink" for a certain usage, for example an Ampy Automation electricity meter (below), you may wish to consider the Enica Opti-Pulse LED sensor. At 24 it was a case of "plug and play" the sensor and connect with a Idratek ODI.

    http://www.enica.co.uk/optipulse.html

    WP_20130525_002.jpg

    Hope that might help others

    Paul

  9. #9
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,676

    Default

    Paul -

    good find ... we've some QRI on the other side of the wall from our (external) meter cupboard, so it's tempting to order one !

    Distance-wise, the run might be a bit under 2m - not sure how far the cable would run (website didn't seem to say), but hopefully it could easily be extended ... (?)

    Chris
    Last edited by chris_j_hunter; 9th June 2013 at 09:36 PM. Reason: typos

  10. #10
    Automated Home Legend Paul_B's Avatar
    Join Date
    Jul 2006
    Location
    Eastbourne, UK
    Posts
    605

    Default

    The cable that comes with the sensor is about 1m in length. I extended mine with my newly acquired soldering skills and used the shielded twisted pair CAT5 cable that I use for the wiring of Idranet. I used two pairs, orange / white, white / orange connected to the sensors red cable and blue / white, white / blue to the blue cable. Blue pair goes to 0V and Orange pair (red sensor) went to channel input on the ODI. The sensor has a shielding cable which I connected to the shielding wire on of the STP which links back to 0V on Idranet at the power supply.

    Paul

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •