How could I constant monitor amps on all circuit-breakers in a 110V panel?

msrobots

I am talking about US voltage and standard household circuit breakers.

What I would like to do is having a propdevice constantly monitoring all electicity used seperated by the circuit breakers in the panel.

So are there breaker with a shunt build in to measure amps? Googeling led me to breakers with some sort remote status-monitoring but that is not what I am looking for.

What would be a save way for a interface to measure about 20 breakers?

Need a hint in the right direction there...

Enjoy!

Mike

Mickster

Current transformer around each leg, feeding an ADC tied to the Prop.

http://www.jameco.com/1/3/current-sense-transformers

Cheers.

Mickster

msrobots

Thank you Mickster, that was what I was looking for!

Enjoy!

Mike

Clock Loop

Ive used and designed with these, they work great, and fast.

http://www.lem.com/hq/en/component/option,com_catalog/task,displayserie/serie,AT/output_type,/

Erik Friesen

Study this before diving into it. Using a current transformer can be dangerous. The value of the shunt resistor is important, and without one, voltages can get dangerously high. Also, double check that the one you use is rated for the amps you are using it for.

Clock Loop

[img]http://www.digikey.com/Web Export/techzone/sensor/article-2012august-the-basics-of-current-sensors-fig1.jpg[/img]
http://www.digikey.com/us/en/techzone/sensors/resources/articles/the-basics-of-current-sensors.html

This cannot be done safely for less than 400$ So if you cannot spend at least that, don't do it.

Erik Friesen wrote: »

Study this before diving into it. Using a current transformer can be dangerous. The value of the shunt resistor is important, and without one, voltages can get dangerously high. Also, double check that the one you use is rated for the amps you are using it for.

OH YEA, uhh, I would not use a transformer in a power supply situation, the things you connect to the end create too much emi/shorts/ov/oc conditions to rely on the isolation abilities of 1250v. these are not hall effect devices that I posted.

Mickster wrote: »

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I didn't see that in his post before, you are right, with a wall panel, I would never use that 3rd transformer on that page, I thought those were the kind I posted, cause they have holes in the center.

NEVER use a transformer in a residential or commercial installation.

The idea is, you should NEVER even cut the isolation on the ACLINE.

You clamp a precise device that can measure the magnetic resonance of the HOT leg on AC. (technically it could be done with the neutral leg, but because of the way grounding works....)

The device I posted is a hall effect device that allows a standard gauge AC wire to be inserted directly through the center of the device.

It DOES NOT interact at ALL with the AC line. It is a device that is completely isolated from the line you are measuring.

I used them in measuring pwm for brushless ac motor control. (we monitored 600v DC pulses with emi of 1kvs from braking/stalls/etc)
No way you can monitor any ac of high voltage with anything of small size, and have large current (30A), and still be affordable.

Ac lines cannot be trusted enough to use transformer monitoring.. Too much emi/lightning/shorts/etc. (not to mention over current conditions)

This device is made for industrial conditions. It goes around the AC hot insulation. It measures using hall effect in the ac wire.

This is the fancy one, but they have cheaper DC ones that would still measure 1/2 the signal, which would still let you see approximate line use. (how hard one phase pulls in one direction)
http://www.lem.com/hq/en/component/option,com_catalog/task,displayserie/serie,AT/output_type,/

$50 http://www.digikey.com/product-detail/en/AT 50 B10/398-1082-ND/1815420
$55 x 20 breakers = $1100
Some devices need loops to increase sensitivity for your installations average current range, The datasheet talks about it.

Here are the more devices. The high voltage wire is inserted through the center of it, again complete galvanic isolation.
Some of them allow pcb mounting (cheaper price) (20$ each at digikey)
http://www.alibaba.com/showroom/lem-hall-effect-current-sensor.html

Mickster

http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface

Mickster

MJB

Those are quite cheap - but of course you should know what you do at mains voltage!!!

http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Zero-To-Fifty-Amp-Integrated-Conductor-Sensor-ICs.aspx

http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&KeyWords=ACS712

msrobots

Thanks for all your help,

I am aware of the danger of main-acc, thus my question was about a 'save' way to do this.

I see now that this is more expensive then I thought it will be - spending $1000 is way out of my reach. I was thinking that with all that house-automatisation around lately there would be some circuit-breaker with sensor-output.

My basic plan was about the same as the arduino-project pointed out by mikster. Just that I simply wanted to put all of it into the Panels. After removing the cover and looking inside I see that it is already pretty cramped in there and I do not want to risk any damage. Neither to me nor the propeller I wanted to use.

Since I am more a software then a hardware -guy I think I will postphone this until I understand more about what I am doing. So back to the books.

Enjoy!

Mike

smbaker

You might want to look at http://www.theenergydetective.com/. I'm using one of their monitoring systems in my panel. By default it only monitors two conductors (i.e. one 240V circuit), but you can buy additional modules to monitor up to 6 total conductors. It uses clamp-on probes. I realize it's not as fun as inventing your own, but it has the benefit that somebody has already thought about the hazards related to working inside the panel.

One issue is getting the "data" out of the panel enclosure. The TED uses powerline modulation (similar to X10 home automation technology).

Another option you might want to look at is monitoring at the point of use. Check out the tweet-a-watt: http://www.ladyada.net/make/tweetawatt/

Finally, a quick google reveals an interesting IEEE paper: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5433631 "A retrofit 60 Hz current sensor for non-intrusive power monitoring at the circuit breaker". I'm not currently an IEEE member, so I can't read it. From the abstract:

IEEE wrote:

We present a new sensor for power monitoring that measures current flow in a circuit breaker without permanent modification of the breaker panel or the circuit breaker itself. The sensor consists of three parts: an inductive pickup for sensing current from the breaker face, an inductive link designed to transmit power through the steel breaker panel door, and a passive, balanced JFET modulator circuit for transmitting information through the inductive link. The demodulated breaker current signal is available outside of the breaker panel door. This sensor provides a solution for low-cost, non-intrusive retrofit of any circuit breaker panel for centralized power monitoring.

rosco_pc

Or Fluksmeter: https://www.flukso.net/

Rforbes

msrobots-


Perhaps this would work for you? It's not quite the same as what you are looking for but close.

I'm actively looking for solutions to a problem similar to yours. I don't care to measure the AC current, but I need to verify that I have AC current flowing (Using it as a proving switch) I'm considering this item:
http://www.crmagnetics.com/Products/CR9650-P134.aspx

It's an AC current switch which uses an NPN or PNP transistor output in it's full on or full off state if AC current flowing through the CT is above X amps. They have several different models to choose from.


I'm not sure how to interface the output of this current switch to the propeller IO- if anyone can offer guidance, I'd surely appreciate it. I've gotten myself confused on the data.

Robert

frank freedman

Just remember to check code/local ordinances. Also the individual hot leg of each wire will be behind the inner panel cover and you will be possibly reaching and installing near always on line side bussbars!