what would work best?

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jheerink
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what would work best?

Post by jheerink »

I,am monitoring an controlling the power/gas usage of a school.
It's a middle-size primary school and we've been working hard to reduce the overall power consumption.

we've installed plugwise/solarpanels to monitor and reduce usage.
Now beside the solarpanels which are already monitored i want to start monitoring the usage of gas and electricity.

I like to have a "live' display of usage, and daily use etc. The electra meter is a 3-phase 63A system. The gas meters consist of 2 meters with around 50 mtr distance between them. Water meter could be measured aswell, they are also like 50 mtr's separated

In total we would have 5 meters to be monitored, 1 elec, 2 gas and 2 water.

any advise what system would work best. ? And be also cost effective. (read not too expensive.
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Re: what would work best?

Post by Henk »

Start with checking your meters if an outside sensor will work.

This sensor is light sensitive and will be placed on an electricity meter .. in case of an old meter it will check the rotation of the disc by sensing the black mark of the edge of this disc so counting the revolution and dividing by the number of revolutions per kwh (like 300 or 600 revs/kwh) . Modern meters will have a flashing light and again the number of pulses will be counted. Placing the sensor can be tricky special with disc ....

This sensor can also be used for a gasmeter - if the meter has a reflection mirror hidden in the 0 or 6 in the rotary counter ..so check your meter not all meters will have this mirror option ...

Watermeter - it is harder some have a rotation disc and again with a light sensor you may count the revolution .... modern types will have a rotation magnet (field) and you should place a reed relais on the meter ... some discussions are in the forum on this type of watermeter.

The sensors are wired connected to a controller and this controller will communicated the readings to a PC - on the PC processing of the collected data .....

for more information check www.enymate.nl / also rfxcom has offerings

An alternative method of reading electricity meters is using a current clamp - in the clamp is a coil measuring the current ..... in case of interest i will get you some vendors ...

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Re: what would work best?

Post by jheerink »

It won't be Anymate. We are also operating some solarpanels (at the moment 11Kwp in the near future 26Kwp) We will return energy to the grid but that will also count as usage ( it measures the little red flashing light, that flashes also when returning power) That won't work then. Weáre now looking for a system that measures direct on the supply calble to the meter.
Last edited by jheerink on Sat Mar 05, 2011 6:34 pm, edited 1 time in total.
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b_weijenberg
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Re: what would work best?

Post by b_weijenberg »

The RFXMeter with RFXPwr and CT's can be used to measure power usage on a 3 phase network.
http://www.rfxcom.com/sensors.htm#70088
The accuracy is about 2%.
The voltage and current are measured so you will have a real power usage indication.
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Re: what would work best?

Post by jheerink »

Ok That could work But wahat will be measured when we are feeding the grid ? Will it start running back or
also count the returning energy as usage ? Maybe we will have to wait for a real Smart meter. We can measure gas/water
with previsous mentioned systems then
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Re: what would work best?

Post by Post-IT »

This is more or less a household product, but it will do the job perfectly:

http://www.diykyoto.com

I works with 3 phase systems, return power and makes some nice graphs if you want.
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Re: what would work best?

Post by b_weijenberg »

POST-IT,

Does it measure the consumed power and delivered power and report this as separate values?
Does it measure voltage and current with cos-phi to indicate the real power?
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Re: what would work best?

Post by Post-IT »

The only things I can find in the GUI is about average and current power usage, no cos phi.

There is a specific document about energy return values:
http://diykyoto.helpserve.com/index.php ... ditemid=32

BTW, be aware, this system uses the 433Mhz frequency so it might interfere with other 443Mhz equipment. I'm currently trying to figure out some connection problems which seem to be due to other 433Mhz systems (X10 and more).
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Re: what would work best?

Post by b_weijenberg »

I guess the diykyoto device has only a current sensor and no voltage sensor.
This is like the OWL CM119 that measure also current only and uses a fixed parameter for the voltage.
Those device can be used perfect for a power usage indication but are not very accurate due to lack of the real voltage parameter and phase shift parameter.
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Re: what would work best?

Post by jheerink »

We will probably try the new currect cost envy 3-phase system. It,s not very expensive
has a nice interphase and works with Google power monitor.

we want to show the usage of the building, so the free google power monitor would
be great. We wil order it probably next week and will update later how it went.

total cost should be around E 150,- including 3 sensors and internet connection box.
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Re: what would work best?

Post by jheerink »

Quick update

The currentcost system (ENVIR) is up and running.
installation is easy, internet connection even easier, and de data show up
nicely on internet and on google powermeter.

The problem is still that our solarsystem generated power that flows back also registers as usage.
There will be a solution eventually for now we will have to live with it.
The best solution will probably a second set ,measuring the different solar panels and split them from the users
Both systems then should be uploaded to the software One source as usage and one source as generated power.
The goal of the system was mainly to
locate unwanted users and try to eliminate them. Time will tell if that works out.

We use it in a medium size school building (average use 50Mw per year) So even reducing a few percent
will earn itself back in no time. (Total investment was around E150,-)
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