Sub-Meter Electricity Monitoring

[Gumby]

Yes, look for DIN rail mounting energy meters. You can get single and 3 phase ones, normally intended for industrial machinery. Quite sophisticated and usually with RS232 or RS485 output. Some have pulses that could be used with the Idratek pulse counting for energy monitoring.

Something like this: http://www.pjwmeters.co.uk/product_detail.php?id=43

Because they are inline they can monitor current, voltage, true power, often supply frequency etc etc. Integration into Idratek is a different question ...

*Updated* wrong link - actually this one isn't inline, but does measure voltage via additional connections.

[KirasHome]

Last call for interest in bulk buy DIN rail single circuit units. I have a couple of candidates in mind, but obviously want qtys before approaching suppliers.

Obviously dependent on price, but I'd be interested in 4.

Thanks, Jamie

[chris_j_hunter]

>DIN rail mounting energy meters ... quite sophisticated ... usually with RS232 or RS485 output ... pulses ... for energy monitoring ... can monitor current, voltage, true power, often supply frequency ... etc ... integration into Idratek is a different question ...

thanks, interesting ... probably wouldn't like the price, though ... but looks like another example of where a general purpose serial interface into Idranet & Cortex might be handy (!)

wonder if a simple circuit based on a transformer + bridge rectifier + smoothing capacitor, or one of the many redundant wall-warts we have lying around, would do the job, connected to a QAI-001 - would have to calibrate it, of course, but a good multimeter & varying the household load (our E7 thermal stores will run towards 100A) might provide sufficient voltage range for that purpose ??

if that would do it, maybe the wall-wart doesn't have to be redundant - we're using LED lights for lighting some areas, and one or two of them could be on permanently ...

or maybe we could tap into one of various items of equipment that are left-on permanently ... radio, hi-fi, etc ??

[Karam]

Guess it depends on whether you're looking for short lived transients or persistent overvoltage. The QAI as it stands is not really designed to sample at high speed and indeed you could get high bandwidth usage if you do operate it without filtering.

If I remember correctly the electricity suppliers (assuming its not your own generation) are duty bound to supply within certain voltage and frequency tolerances and will perform logging at your feed over a period of time if you have reasons to suspect problems. In terms of persistent overvoltage I think the upper limit is 253V RMS.

In terms of interface to 3rd party products - its possible to write your own application to get the data in from the 3rd party product and then interface to Cortex via the Cortex API

[chris_j_hunter]

>short lived transients or persistent overvoltage ...

not transients ... five-minute averages, say

>253V ...

we've seen 257 occasionally, mostly it's 245 or so, at the socket nearest the consumer unit ... high enough for us to ask them to swap tappings, before we move in ...

>high bandwidth usage if you do operate it without filtering ...

not sure I understand ... presumably that's traffic on Idranet (?) ... but what sort of filtering are we talking about, please ?

>write your own application to get the data in from the 3rd party product and then interface to Cortex via the Cortex API ...

then that looks like that's what we'll be doing ... is anyone aware a simple but effective sender / receiver of ASCII strings that'll work under Windows XP ... when I last did this sort of thing, it was with QuickBasic (VisualBasic for Mac, sort-of), which had such capability in a couple of its functions, and using them it was easy to do the rest (SWMBO-friendly control of the hi-fi), but that was Mac, and MS discontinued QuickBasic when the Mac went 32-bit - ages ago !

[Karam]

>high bandwidth usage if you do operate it without filtering ...

not sure I understand ... presumably that's traffic on Idranet (?) ... but what sort of filtering are we talking about, please ?

Yes fast signal variations could result in many packets being sent from the QAI if it is sampling fast and filter parameter low. So some control can be effected by the module itself however if you're happy with longer time frame averages then its probably best to do most filtering on the analogue signal ie. simple low pass capacitor/resistor. Also you need to be careful to ensure that you are connecting to a step down supply with suitably rated isolation

[chris_j_hunter]

ah, good, thanks !

[Gumby]

Chris - could you take that to a new thread for clarity. Cheers, David.

[chris_j_hunter]

done ... have moved the water meters to the Water Controls thread ... !

also noticed this :

Another electric meter with pulse output (probably too expensive) :

http://www.smartpowershop.co.uk/product/diris_a20/

and some water & gas meters with pulsed output, too - but for them, see the Water Controls thread !

[chris_j_hunter]

BTW - current Current Cost web-site makes interesting reading :

http://www.currentcost.co.uk/

Extract : CC128 ... Energy Monitored: Electricity (gas, LPG, oil option in development) ... Sensor Coding Recognition: 10 channel (each three input potential) ...

NB: click on the Products tab, and it'll offer Classic, CC128, Data Cable & Transmitter options, and IAMs (Individual Appliance Monitors) are now said to be coming soon ...

so ... would this be a better approach ???

NB: no prices yet, that I could find ...

[spellinn]

Current Cost integration with Cortex

BTW - current Current Cost web-site makes interesting reading :

http://www.currentcost.co.uk/

I've just aquired the new current cost device, and am looking at ways at interfacing it with Cortex.

It outputs an XML file onto a RJ-45 port, which can be interfaced with your Cortex PC using a USB cable.

The tricky bit is how to get this XML data into a format that Cortex can understand. It's documented, so it would be great if Idratek could add a logic object to Coretex that understood the XML input from the Current Cost devices.

Cheers

Neil

[chris_j_hunter]

I think that's your cue for getting into Cortex API - see last para' of post number 64, above !

[spellinn]

Api

I'm not really a windows programmer unfortunately..apart from the odd bit of VB script.

I'm wondering if it might be easier to use xAP to interface the two, given Cortex already has xAP support. Will still involve writing some code though

Cheers


Neil

[chris_j_hunter]

>VBScript ...

IIRC, it would be possible to use this to write some sort of application / addition / extension to 'XP, using WSH (Windows Script Host) ... not tried it, but it's on my list of things to do !

>use xAP ...

ISTR Kevin was looking at this ...


BTW, I think the XML for the CC128 differs in some ways from that for the Classic Current Cost device - see : http://dalelane.co.uk/blog/?p=389

[spellinn]

xAP might be the way..

I've just found this thread..although the site mentioned does not have any downloads for xAPPower

Cheers

Neil