New 3 Phase Firmware

I’ve seen references to new improved firmware for 3 phase.
Can you pls provide the link to download this for emonTx - I’ve got very confused linking in circles.
I’ve previously uploaded firmware using PlatformIO
Many thx

I understand it is available on Github, but for some unknown reason, the zip container has been removed and you need to download all the parts separately. I cannot use platformio so I am unable to offer any advice on that. If you follow the instructions in ‘Learn’ for using the Arduino IDE, it will certainly compile and load faultlessly.

Robert …
Thx for yr super-fast response (and for many responses in the past)
I realise that you are not ‘in charge’
I’ve spent £100’s in the OEM shop but am beginning to wonder whether 3 phase users are second class citizens!
It should be easier and PlatformIO is a recommended approach.
Sorry for the rant

PS …
3 phase users purchase more from the Shop - 3 times as many CT’s for example
And large installation users (like myself 30 kWp) buy a lot of emonTx’s -5 in my case

Hello, you can find the three-phase firmware here. It works fine with Platformio.
GitHub - openenergymonitor/emontx-3phase: emonTx 'approximate' 3-phase firmware

Robert Wall offers very good and patient support. The fact that it is officially less well supported is simply because three-phase connections in Wales are not standard in residential buildings.

Are you guys referring to this repo?

if so you can either clone it like any other repo or you can download it as a zip by clicking “Clone or download” then “Download ZIP” is the direct link to download a zipped folder.

The front page gives a link to uploading using Platformio if that’s your preference, not all of us enjoy using PlatformIO so a lack of experience with it means we are not really in a position to help you much with that.

You can include England, Scotland & N.Ireland in that.:smile:

1 Like

Belated thanks, guys …
I located the zip folder containing file platformio.ini.
And using platformIO, have successfully burned it to an emonTx.
I did it from my Windows laptop using the Shop USB to UART adapter.
The emonTx is now running OK - albeit temporily in a single phase location - OK for test purposes.

General comments …

The ref to needing a Windows driver for the USB/UART adapter is a little obscure. Could it not be given more prominence in the Guide/Firmware Modification section?

Locatiing firware is almost impossible …
Starting with Resources
to emonTx V3
to Hardware & Official Firmware
to emonTx V3 Resources
Takes me full circle back to Resources

Can there not be a clearly signposted location for the latest single and 3 phase firmware?

John Banks

I too find it hard to know which is the up-to-date offering, because the policy here seems to be to never label anything as ‘superseded’ or ‘obsolete’, or anything like that. Had you clicked on the blue “openenergymonitor/emontx-3phase” in Paul’s post (No.5), you would have gone straight to the repository.

If you’d installed the Arduino IDE following the instructions in ‘Learn’ (I cannot nor will ever support Platformio), then I think the full instructions for the Windows drivers are in that. I, like many of us here, don’t need them, as we run various Linux versions.

For calibration purposes, note that if you put all your c.t’s on the same cable, phases 2 & 3 will read exactly -0.5 × the correct power.

Robert …
Thanks for the tip which I’ve just tried.
I assume you mean that Ph2 + Ph3 total will be minus half that of Ph1?
Minutes ago …
Ph1 794
Ph2 -328
Ph3 -138
So I’m a bit off … 794 plays 932
Vrms was 252.8
Would you expect that degree of difference with the new 3 phase firmware?
(Me using Windows and platformIO can’t explain it :slight_smile:)
John (Banks)

No, not total, each. Think of the phasor diagram, and Phase 2 & Phase 3 projected onto the line of Phase1 - they are on the opposite side and half the length. (or look at the diagram in ‘Learn’).
So if V = 250 V, I1 = I2 = I3 = 8 A, P1 = 2 kW, P2 = P3 = -1 kW.

Are you calibrating, or have you tried to calibrate, it? Although this version is less sensitive to some errors than the previous, you really need to follow the exact calibration procedure in the documentation.

The differences you are seeing could have contributions from the current calibration (due to tolerances in the c.t’s and burden resistors) and phase errors in the c.t’s and v.t.

If you go to that phasor diagram again, moving the Ph 1 phasor a little ahead or behind its proper place (an uncorrected phase error between c.t. & v.t.) makes little difference to the length of the projected phasor. Do the same with the ones that are 120° round from that and you can see it makes a huge difference in comparison. That test is quite sensitive - it won’t be nearly as bad in the real world, until you get a load with a very low power factor.

So yes, it looks as if your phase correction needs adjusting (but you need to get the currents right first).

Robert …
Thanks for your comments/guidance.

I’ve studied the Learn resource on Calibration which understandably has not yet been updated for the new 3ph firmware.

Using an old kettle, I stripped the outer insulation from the lead to access the live only and hooked the 3 CT’s to this and also my clamp meter (approx cost £40).

I did 3 trials each time changing the sequence in which the CT’s were plugged into the emonTx. Before each trial I disconnected and then reconnected the 5V supply to the emonTx to reset it.

Results below …

 	emonTx	Clamp Meter
 	P1	P2	P3	Vrms	Meter (A)	Meter (V)	Meter (w)
1	2886	-1504	-1356	246.7	11.77	243	2860
2	2911	-1502	-1367	244.8	11.55	240.6	2779
3	2874	-1482	-1337	243.4	10.78	239.4	2581
 	Vrms-V	P2+P3	P1-(P2+P3)	P1-w	P1/w	 	 
1	3.7	-2860	26	26	1.009	 	 
2	4.2	-2869	42	132	1.048	 	 
3	4.0	-2819	55	293	1.114	 	 

The meter readings are not precise – they continually fluctuated – so an eyeball mid-point and it took a few seconds to walk down my hall to my laptop to get the emonTx readings.

I conclude that I do not have a ‘bad/dirty’ CT.

emonTx records Vrms approx 4V higher than actual.
So guess I should now adjust double vCal = 268.97 to 268.97 x 240/244 = 264.56 – is that correct?

Are any adjustments necessary to double i1Cal etc = 90.91 ?

Consistently P2 is more than half P1 and P3 is less than half P1 (ignoring minus sign). Does this suggest adjusting the double i1Lead etc = 2.00 ?

Thanks for your comments/guidance.
John (Banks)

Nor (probably) won’t be. The full instructions specifically for the 3-phase sketch are included as a .pdf file in the zip package.

Yes, that’s right.

Probably. Bear in mind that the calibration constant is for the combination of c.t. and input, so once calibrated, you should not move the c.t’s to different inputs. You need to look at current (not power, and especially not power for phases 2 & 3) when adjusting Ical, then you look at power when adjusting iLead.

You might find that adjusting LOOPTIME 5000 (5000 ms) to be closer to your meter’s update rate makes it easier to adjust the calibration to match your meter.