I am an electrician in the Netherlands.
We are looking for a system that can monitor and log the current and voltage of a 3-phase electrical installation. I have read that this can mostly be done with the emonTX, except that it can only measure the voltage of one phase, and needs to estimate the voltage of the other two phases.
However, what we need is to measure all 3 phases seperately, because when the building is at the end of a long cable without a highvoltage mains stepdown transformer, the voltage can fluctuate easily.
We already know of this problem occuring at some of our clients' buildings, but in the past, it was only a problem of the voltage being too low.
Recently, with the increasing amounts of solar panels being installed on large farm buildings, which are sometimes connected to a mains cable that only has a stepdown transformer on one end of the cable, not both, there is a new problem.
Instead of a large load (power consumption) causing voltage to drop, a large amount of solar panels (power production) will cause the voltage to rise.
In one case, one of our clients called about their solar inverter (not installed by us) that did not work during the expected peak production hours.
The mains voltage in the building increased to 253 volts instead of 230 volts, and the inverter shutdown as a safety measure.
Now, I am not a programmer, so I only know enough about Rasberry Pi and Arduinos that I need to not try and program them for risk of breaking them.
Can I measure the mains AC voltage of each phase with a seperate emonTX, the current of each phase with one of those, and connect those 3 emonTX's to a single emonBase?
On http://shop.openenergymonitor.com/emonbase-raspberry-pi-web-connected-ba... and http://shop.openenergymonitor.com/emontx-v3-electricity-monitoring-trans... what options do I need to select?
If we were to install this at a client's house / farm building, we would install all devices in close proximity.
Can the data from three emonTX's be sent to the emonBase via cables, or is wireless the only / simplest option?
If this question has already been answered on this forum, I apoligize for posting this, as I could not find it.
Re: Monitoring 3-phase installation where uneven mains voltage decrease/increase can occur
Yes, you can use one emonTx V3 per phase.
Yes, you can send the data from all 3 to one emonBase.
"Now, I am not a programmer" makes me say do not try to connect with cables. Wireless will in most cases be the simplest option, as it is part of the default sketch and the default emonHub.
EmonTx V3.4 Options: Up to 4 current transformers - you say you want 1 only per phase, but you can add more (PV infeed?) later; ac-ac adapter with a plug to suit (euro?); I guess fully assembled & cased, unless you have a different way in mind - to mount all 3 in a plastic enclosure?
You will need a programmer because the 3 emonTx's must each have a different node number, and that will mean editing and reloading the sketch on one.
I will not answer the Raspberry Pi options as there are people here better placed to answer that.
Re: Monitoring 3-phase installation where uneven mains voltage decrease/increase can occur
Thank you for your quick reply, Robert!
By "I am not a programmer" I meant that I don't know how to write something myself, but if all it takes to connect 3 emonTx's to 1 emonBase is to change a number, I can probably figure that out.
I only worked with an Arduino once before, and I only barely made that work with instructions/advice from a programmer, until I shipped it to her and she made it work properly.
We may also use it to measure PV panel output, but we'll most likely use it to help troubleshoot electrical faults that happen over time, i.e. problems that don't occur when we are there to look for the source of the problem.
There are already tools available for that, (Fluke has some) but from what I've read, all of those are a lot more expensive than this would be.
Re: Monitoring 3-phase installation where uneven mains voltage decrease/increase can occur
"You will need a programmer"
Actually I just found this on http://shop.openenergymonitor.com/emontx-v3-electricity-monitoring-trans...
"If more than two emonTx's are required on the same network then further nodeID values can be set via Arduino Sketch Upload. This can be done at time of purchase if requested (leave order comment at checkout)."
My boss emailed me yesterday, asking me what options are needed for the emonBase to work, as he wants to buy that, an emonTx, AC/AC adapter and 4 current transformers so we can try it out and test it ourselves. (we have a 3-phase variable transformer capable of 0 to 260 volt AC which we can use for testing it)
Re: Monitoring 3-phase installation where uneven mains voltage decrease/increase can occur
That page has changed since I last looked! Again, I don't know enough about the present state of the RPi and emonHub to be able to give you an answer on the options you need there.
Re: Monitoring 3-phase installation where uneven mains voltage decrease/increase can occur
The link has gained a colon, without the colon it works ok.
if you let the guys at the shop know I'm sure they will update the node ids for you prior to dispatch, but it may be prudent to order a programmer anyway. If you have an issue, need to calibrate, change or update any of the emonTx firmwares you're stumped without a programmer which incurs extra time and postage to get one at a later date. We can talk you though a small adjustment if you do have one, better to have and not need than need and not have. (they are not that expensive http://shop.openenergymonitor.com/programmers/)
"Can the data from three emonTX's be sent to the emonBase via cables, or is wireless the only / simplest option?"
Only, no, simplest, yes!
I won't go through all the options (and their pros and cons) here but anything other than the default RF method is (currently) quite an undertaking with more than a single emonTx (direct serial). It is possible but it would be a bespoke solution which unless you are unable to use RF an alternative is unlikely to justify the time, effort or learning curve for a single install unless you were already well versed in these things, there certainly isn't an "off-the shelf" solution I'm afraid.
Paul