OpenEnergyMonitor Forums

Re: Open-source wind monitoring options

Suneil — Wed, 13 Apr 2011 14:09:27 +0000

Hi Alex,
good to hear from you. Yes, if you have the list of commercial wind loggers, it'd be interesting to see what's out there, I've seen a few, and they range a lot in price. In terms of a DIY open source version, I think its pretty straight forward if you have a well calibrated anemometer. Open source also allows greater flexibility and longer term maintainability of the hardware, so try recommending this to your client. as well as more people can benefit from using the technology! :)

All the best with your project

Suneil

Open-source wind monitoring options

Lomeli — Wed, 13 Apr 2011 08:38:55 +0000

I've run across two open-source wind monitoring options while researching equipment for a project to mount a small wind turbine to a building. [Yes, I know that mounting a wind turbine to a building is probably not a good idea! cf Warwick Wind Trials] Interestingly, neither one is explicitly open-source -- only by request and in consultation.

APRS World, Inc.
Their web site doesn't say that they are open-source, but I have confirmed that they are, over the phone. They are "...working on a new system called ReDAS (Renewable Energy Data Acquisition System). The new system does need a live internet connection on site, but it will be much more flexible and expandable than our current offerings. It allows you to simultaneously monitor multiple outputs from different inverters, along side a variety of other wind and weather sensors. We're still working on the new web interface and display for this new system..."

Etesian Technologies
The company owner was working on an open-source wind data logger. They also sell a nifty wireless, battery-less, anemometer-logger-display pair. The anemometer generates enough current to send the data packets down to the logger and display.

I'm not interested in creating the hardware and software, only in explaining the options to my client. In turn, I doubt they will want to go the open-source route, although I'll certainly present it as an option. At the same time, I can't imagine a technical college being happy with Fat Spaniel as a display solution. So I'm still looking... if you're interested, I can send my annotated compilation of web sites that I've found so far.

Best regards,

Alex D
Clean Energy Partners
Madison, Wisconsin
USA

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SuperCard 3DS
R4 for 3DS

Arduino data throughput

ksquared — Mon, 11 Apr 2011 18:12:35 +0000

I am trying to setup an energy monitor with the Arduino. But what I'm wondering is what is the maximum data throughput with either just serial output or using the ethernet shield. I have tried to research this, but can't find any definitive information that I can understand. Of course, I'm very new to this too, so hopefully people will be understanding.

Re: How to set up multiple data steams with Pachube

Paul — Sun, 10 Apr 2011 20:13:16 +0000

Figured out problem. The content length was the main problem and the client.println();

However, I am trying to find a way to find the length of double for content length. I see ways to do it for ints and strings but I cannot find any examples to find length for doubles.

Thanks.

How to set up multiple data steams with Pachube

Paul — Sat, 09 Apr 2011 21:26:50 +0000

I have downloaded the NUClient Pachube, however, I made changes to the code because I am using an ardiuno ethernet shield. I have one graph working fine but cannot figure out how to add another feed. Has anyone put up their data on pachube and have sample code?

Here is the code:
/*
Nuelectronics ethernet shield client example - sending data to pachube
Created by Trystan Lea, April 31 2010
GNU General Public Licence: [openenergymonitor.org]
*/
#include
#include

//Set these to your feed ID and pachube api key
#define SHARE_FEED_ID // this is your Pachube feed ID that you want to share to
#define PACHUBE_API_KEY "" // fill in your API key

byte mac[] = { 0x90, 0xA2, 0xDA, 0x00,0x3B, 0x8F};
byte ip[] = { 192,168,2,50 };
byte gateway[]={192,168,2,1};
byte subnet[] = {255,255,255,0};
byte server[] = { 173, 203, 98, 29 }; //Pachube.com

//Some variables to send
double valA = 10.23;
double valB = 22.34;

int content_length;

Client client(server, 80);

void setup() {
Ethernet.begin(mac, ip,gateway,subnet);
//analogReference(EXTERNAL);
Serial.begin(9600);

delay(1000);
Serial.println("Connecting...");

}

void loop()
{

//Do things that need to be done even when
//the ethernet shield is connecting etc here.

//If the client has finished sending.

//Increment values so that we can see something happening!
valA += 1.2;
valB += 0.2;

//Do things that only need to be done when
//the client has done sending.
delay(10000);
//Tell the client that it is not done and it needs to start sending again.

Serial.println("start");

//client.process opens and closes the client connection
//It returns a one when the connection is at the data
//sending stage.
//client process will also check for pings
if(client.connect())
{
Serial.println("connecting");
//This seems to work set as 1?
content_length = 1;

// 1) Send feed id, pachube api key
client.print("PUT /api/");
client.print(SHARE_FEED_ID);
client.print(".csv HTTP/1.1\nHost: pachube.com\nX-PachubeApiKey: ");
client.print(PACHUBE_API_KEY);
client.print("\nUser-Agent: ecotinker");
client.print("\nContent-Type: text/csv\nContent-Length: ");
client.print(content_length);
client.print("\nConnection: close\n\n");

// 2) Send the data - comma seperated
client.print(valA);
client.print(",");
client.print(valB);
client.println();
//sends all of the above
client.stop();
Serial.println("data sent");
}
else {
Serial.println("Failed to connect to client");
}

}

Thanks,

Paul.

Help using bridge rectifier instead of voltage divider

BenFranske — Tue, 05 Apr 2011 06:09:41 +0000

Hello! I'm trying to create a circuit to measure current used by a motor with an Arduino using a current transformer and a bridge rectifier. I'm afraid it's been too long since I've done AC circuits or calculated RC values so I'm having some difficulty making sense of the numbers I'm getting, any help would be greatly appreciated.

My specific hardware, with links to the datasheets where applicable:
CR Magnetics CR8410-1000 Current Transformer
Fairchild DF02M DIP Bridge Rectifier
Currently using 200 ohms of burden/load resistance on the AC side of the rectifier for the CT
Currently using 100uF capacitor from the positive output of the rectifier to ground
Currently using 10K resistor in parallel with the capacitor
Measuring across the dc side of the rectifier

Based on the datasheet for the CT I thought I should be using a 100 ohm burden resistor but the voltages across it that I'm seeing when the motor runs (it's on a sump pump either 1/4 or 1/3 HP I think) are lower than I expected based on my calculations (all well below 1V) so I bumped the burden resistance up to 200 ohms to raise the voltages. With a multimeter I'm now measuring voltages around 1.4 Vdc when the motor is running, this still seems a little lower than I'd expect...

One of the things that's somewhat important to me is getting an accurate run duration (being able to detect when the motor starts and stops with reasonable accuracy, say 1/2 second or less) and I'm somewhat concerned that the capacitor is causing a delay in detecting the stop time. If I'm thinking correctly I could reduce this lag by reducing the capacitor size however the only other capacitors I have on hand are a couple non-polarized 1uF and some tiny ceramics. If I were to order another size capacitor what would be ideal.

The circuit itself is a dedicated 20A circuit so ideally I would be able to measure up to 20A but realistically I expect the motor draws somewhere around 10A. I'm located in the US so this is 110/120v. Again, any help is greatly appreciated!

Burden resistor sizing

reh — Sun, 03 Apr 2011 19:02:53 +0000

Hi

I have a circuit board to take inputs from 4 CT sensors - it is basically 4 copies of the single CT sensor circuit. I want to have different inputs sensitive to different current ranges, but am having some trouble choosing the burden resistors for low current values (i.e. the most sensitive input).

using the same CT sensor and a test 8.6A purely resistive load, i get the following results (the first column is the burden resistor in Ohm as directly measured on the board; the second is the minimum-maximum reading from the Arduino when using an RMS 8.6A current; the third is the consequent calculated maximum RMS current that can be read; the fourth is this range time the burden resistor value):

burden		min-max A/D	max current range	range x burden
30.2		106		83			2509
51.4		157		56			2883
102.7		259		34			3492
997		340		26			25823

According to my reading of the detailed system design page, the last column should be a constant (related to the number of turns in the CT sensor and the bias voltage). The agreement is pretty good for the first couple of lines, poor for the third, and useless (out by a factor of 10) for the last.

Is there a more accurate way of calculating the burden resistor value, or should i just use trial and error?

Brand new

Jeremy.grimm — Thu, 31 Mar 2011 19:10:02 +0000

Hello,

I am brand new to this and want to build a wind turbine. I have some questions that I can't seem to locate the answers to. All I want to start with is powering my little shed in the back yard with a turbine. This is something that I will not use every day for energy, but I will have an air compressor for airing up tires (should only need to run at about 10 minutes at a time) maybe a circular saw once in a while, an electric drill once in a while, and 2-4 lights once in a while. I want to know how do I keep my turbine from overcharging the battery bank. Is there a product that I can get that will shut off the power to the bank when it's at peak charge? or am I going to have to manually turn it on and off to charge it? I want to run power to my shed, and I though this would be a fun and inventive way to do it. Thank you.

Re: Multiple current sensors

zayanimeister — Tue, 22 Mar 2011 18:41:14 +0000

@reh: nice effort! how far are you? could you share your code?

Re: "Router" energy monitor

Paul — Sat, 19 Mar 2011 17:04:30 +0000

Okay, got Ethernet Shield. I have reflashed my linksys WRT54gl, however, my cable modem is connected to a linksys WRT54g and when trying to connect to my linksys WRT54gl I keep locking myself out of the internet and have to reset my linksys WRT54g. Is there a way to avoid this?

Thanks

Re: "Router" energy monitor

Paul — Wed, 16 Mar 2011 20:56:31 +0000

I was thinking of using a VDIP and WRT because I have them laying around. I thought I could just alter the data logging code so instead of writing a text file it would send it to the router. Been looking around but how to start.

Re: "Router" energy monitor

trystanlea — Wed, 16 Mar 2011 19:52:09 +0000

Hello Paul, Im afraid I dont know of code to do it that way. Whats your thinking behind going for a WRT router and VDIP over an ethernet shield?

All the best

Trystan

Re: "Router" energy monitor

Paul — Wed, 16 Mar 2011 18:48:23 +0000

I have the VDIP1 USB working but now I want to send data wirelessly to the internet. I bought a linksys WRT router and flashed it. I have a usb/ethernet adapter to connect the Linksys to the VDIP1.

I have been looking around for code on how to modify the data logger so instead of writing a text file to a USB it sends data to router to send to the internet and have not seen code on how to do this. Does this sound possible? Ideas on how to get started would be great.

Thanks.

Re: CT PCB Board

zayanimeister — Wed, 02 Mar 2011 08:29:44 +0000

i just read this post on DIY Drones: [diydrones.com]

This guy bought an SMD pick and place machine and is offering his services to anyone in the UK. Could be useful for the future.

Re: CT PCB Board

trystanlea — Fri, 18 Feb 2011 12:59:49 +0000

wow, good work, 459SMD's!! Were only just learning how to design an make PCB's at the moment.. maybe a dozen or so components :)
That would be awesome if you open it up, and let me know if you need any help with using the website.
Thanks
Trystan

Re: Communication

trystanlea — Fri, 18 Feb 2011 12:54:46 +0000

To answer your questions. A restful interface sending data usually in the URL
for example a GET request:

GET [website.org]{"data":"20.0"}

The TCP socket would be opened for every data post.

Data sent every single sample or and averages up to you.

Standard port, port 80

It would be cool to have the option for webserver control, I havent tried it yet. I guess you can setup the arduino as a server and then get the webserver to sent a request to the arduino. It would be good to have both options.

Communication

pyro — Fri, 18 Feb 2011 01:20:36 +0000

From reading on the site it sounds like the general concept is to have a networked Arduino send data to a webserver somewhere. A few basic communications question on this approach:

When is a TCP socket opened and closed?
How often do you send data? Is it a single sample, or averaged?
What port? Most web servers have firewalls blocking ports from incoming connections

My approach has been to have the webserver in control. I use a bi-directional interface with a request from the webserver and the power meter transmitting a reply. Do you invision this type of setup would be compatible with your setup?

Re: CT PCB Board

pyro — Wed, 16 Feb 2011 02:48:45 +0000

64 was only my prototype. I decided to go down to 40 since the board space for the connectors became too large (although I haven't stripped it from the firmware yet. Removing it will allow me to sample faster but changes all the complex timings). It is a true real time system. I am mounting 40 CTs to my 40 space electrical panel. It will measure power for every sub-circuit. It currently does not do power factor.

Currently the hardware cost is very expensive partly because of the low prototype quantities. The PCB is also complex: 760 drill holes, 535 pads, 459 SMDs. It communicates by RS-232 or RS-485. I use the MODBUS communication protocol. I use a simple RS-232/RS-485 Ethernet convertor to get it onto the network. I could not add Ethernet onto the board yet due to the complexity.

I am thinking about opening the project up to this open source project since its a lot of work. I need assistance with the front end web software. And someone to eat up some of this initial cost : )

Re: CT PCB Board

trystanlea — Tue, 15 Feb 2011 09:39:01 +0000

Wow thats quite a board! 64 inputs! What are your plans with it? It would be great to hear how it goes.

Re: CT PCB Board

pyro — Sun, 13 Feb 2011 23:54:25 +0000

I have a prototype running reading 64 channels based on the Arduino hardware. Although I am only using the Arduino hardware, firmware is written from scratch since I need advanced interupts for speed.

I have the hardware design completed and currently getting PCB quotes. The final design supports 40 channels, uses an Atmel processor, but not based on the arduino. I should be testing over the next few months. I will post more information on it after testing. One major concern is safety as mixing 240VAC with communication circuits is difficult to do safely.

Re: Nothing connected and Arduino shows reading !=0 :S

trystanlea — Fri, 04 Feb 2011 09:07:11 +0000

Hey Amin

Did you get a chance to look at the output from the waveform sampler?

It can be found here for anyone else interested: [openenergymonitor.org]

Trystan

Nothing connected and Arduino shows reading !=0 :S

zayanimeister — Thu, 03 Feb 2011 09:50:09 +0000

Hello everyone,

I am having a problem with my setup. I am using a Blackwidow arduino board (with built-in wifi) [asynclabs.com]
with a current sensor and an AC-AC adapter connected to two analog-in pins as detailed on the websote: the same electronics, same 2.5v DC bias, and yet, I have some problems with the readin:

For a 1900w purely resistive load I have a real power lower than the apparent power, and the apparent power is the correct one. The resulting power factor is 0.93 instead of 1.

I am suspecting noise is the source of these problems, and tried to see what's the reading when everything is disconnected, so I connected the board to USB, launched the energy monitor latest sketch and read on the serial port some values for both current and voltage + a power factor of 0.56

I am on my ass, banging my head against the wall, can anyone confirm the same result with their setups?

My biggest worry is that the board is creating this noise, it is not FCC or CE certified :S

PLZ help :'(

Amin
=============
www.bouhablog.com

Re: Problem with USB port and web port

binooetomo — Sat, 29 Jan 2011 04:39:23 +0000

Hi Trystan,
Thx for your enlightment.

I'll take a look into it.

Meanwhile, I also try the newest EthernetShield library from Andy.
Look's like he made a change on how to send the data.
Now the url part have to be in "define" so it hard to make it end-user configureable.

I also have problem with my EthernetShield.
My Board is duemilanove 328.
Whenever I plug the shield on top of it, I lost the usb feature.

Sincerely
-bino-
I think I have to create another Arduino IDE Directory with older Andy's library in it.

Re: "Router" energy monitor

trystanlea — Fri, 28 Jan 2011 22:50:08 +0000

Hello Angel Valor Reed

Thanks a lot for letting us know about your build, looks like a great setup, nice work!

Trystan

Re: Problem with USB port and web port

trystanlea — Fri, 28 Jan 2011 22:47:28 +0000

Hey Bino

The masterEthernetTemplate is for local arduino to arduino Network operation, are you trying to implement this or just ordinary Ethernet connectivity?

If so try the sketch downloadable from here: [openenergymonitor.org]

Trystan

Re: Multiple current sensors

trystanlea — Fri, 28 Jan 2011 22:43:11 +0000

Hey reh

Yes your right the calibration could be different, but i think the difference is unlikely to be significant.? especially if your CT's are the same model.
Are you measuring a phase discrepancy?

Yes you could try switching to a filteredI, havent tried it myself but Im sure it would work

Trystan

"Router" energy monitor

angelvalorreed — Mon, 24 Jan 2011 16:29:30 +0000

Hello Trystan and everybody,

I have reduced the number of modules of the system, from two to just one, by replacing xbees by a Linksys wrt54gl router.

The final system is depicted here:

[picasaweb.google.com]

I have substituted the two xbees, plus the two xbee adapter boards (LadyAda) plus the Ethernet Arduino, with the router. This allowed to cut costs by approximately 40 € ( $ 54).

I hope it can be of interest for you guys, as I think it makes the system easier to setup and to mantain (of course you need to have a wireless modem, but I think these are common nowadays).

I can supply further details on upgrading the router firmware to the open operating system dd-wrt (which I did) as well as supply the new arduino sketch (which now does everything).

I would like to thank Trystan and the rest of the team once again for sharing ideas and knowledge... thanks to you I am monitoring my house and reducing consumption!

Best regards, Angel Valor Reed

Problem with USB port and web port

binooetomo — Fri, 21 Jan 2011 01:59:48 +0000

Dear All ..

I just try to use the software.

Well , I try to simplified the "MasterEthernetTemplate" , since I just want it to read one Analog pin (Pin A3) and send the value to web:
- Strip out the NewSoftSerial call
- Strip out all line that have "laptop" in it.

The ethernet-send is work well.
But I have a problem with USB port.

Whenever I plug the ethernetShield, the USB port become unuseable.
I look to your code and there is ---> Serial.begin(9600);
I knew that you use the default serial to call another unit via readFromPVunit() function.

Is it true that the ethernetShield will always make USB port disabled ?
What about the UART port behind FT232 chip ... is it still fuctioning ?

Problem number 2 : How to make this sketch to send the data on port 8888 instead of 80 ?

Sincerely
-bino-

Multiple current sensors

reh — Thu, 20 Jan 2011 19:13:21 +0000

Hi

apologies if this is the wrong forum - it isn't really a hardware question, but there isn't a software forum.

I'm following the open energy monitor v3.0 design, but with multiple current sensors. I have a question about how to implement the phase calibration in the sketch.

Currently this is done by modifying the filteredV (only), but I guess that the phase calibration takes into account both the voltage and current sensor behaviour, and with more than one current sensor the calibration constant might be different for each.

Is it just a matter of switching the phase calibration to the filteredI measurements and going through the power factor calibration once for each sensor?

Re: Efergy CT appears not to work - what am I doing wrong?

edjones — Sun, 16 Jan 2011 20:17:48 +0000

Trystan,

I am feeling suitably sheepish. Obviously I have just clipped around the whole wire. Will try again, following the simple instructions...

Oh well, now I have 2 CTs :-)

Thanks for your help.

Ed