Multiple power supplies on mega tree

[lizardking]

look in the 101 manual at page 51 on power supplies
http://auschristmaslighting.com/forums/index.php?topic=1889.0
it helped me heaps

 

[i13]

Again, correct me if I'm wrong. My amateur understanding was that the neutral is connected to Earth but the active isn't. Based on this I would have thought the potentials within the power supplies wouldn't match if one power supply's input is swapped and not the other one. It might be a bit of a long shot but couldn't this continue through to the outputs to a certain (hopefully not dangerous but I don't know) extent? If so then it might be the cause of the wire between them heating up.

If you have a wire from the negatives of PS1 to PS3 and PS1 to PS2 then you don't need the wire that is heating up. Having said that, something wrong is causing it to heat up and the other wires will heat up instead if you don't find the problem.

Judging by the wire colours, I also want to point out that it appears (to me) to be incorrect in the Masters box and correct where it is mounted to the board. Regardless, it is something that is different between the photos. It might be worth unplugging all power supplies and checking the cables with a multimeter to see which wire corresponds to each pin on the plug.

 

[AAH]

Again, correct me if I'm wrong. My amateur understanding was that the neutral is connected to the ground but the active isn't. Based on this I would have thought the potentials within the power supplies wouldn't match if one power supply's input is swapped and not the other one. It might be a bit of a long shot but couldn't this continue through to the outputs to a certain (hopefully not dangerous but I don't know) extent? If so then it might be the cause of the wire between them heating up.

External to your house Neutral is connected to Earth so neutral should typically only be a volt or 2 different to earth if you put a meter on it. When you connect active and neutral to a power supply or transformer it doesn't matter which way around they are connected as there is no reference between the input, Earth or the output.

As to the initial problem I think a mudmap that shows the power supplies in there actual orientation and the connections from each of the power outputs to the P12, fuses etc will help. If the whole setup can fit i the 1 photo showing where all the wires go that would help too.
I've been off wiki'ing which is why I was slow responding.

 

[i13]

Yes that makes sense. I should not have said "the ground" to refer to the earth because ground often refers to the negative output. I'm editing that post because we don't want anyone to connect the input to the output.

Back on the topic of what the issue is, I am struggling to think of what might cause this to happen but there should not be any other connections between the power supply outputs other than the negative outputs. There must be some sort of complete circuit happening to heat that wire.

 

[cdjazman]

The strange thing is that I have connected wires as they were last year and it is happening. See attached and hopefully it helps......

 

[scamper]

If all of the lights are working, then I would say it is simply a case of too small a wire.
The wire you are using looks to be around 7.5amp or worse just speaker cable, the power supply you show is a 29amp supply.
If it worked with the same cable last year I would suggest it was getting warm already and not noticed. It could be as simple as a couple of broken strands, corroded or heat affected cable causing some increased resistance in it and therefore getting hotter.
My suggestion is to get a meter and check the current draw. you can also check the potential across the v- wire and see if there is any difference.
Either way, I would be increasing the cable size

 

[fasteddy]

What guage of cable are you using and how many pixels do you have that are powered by each power supply. As scamper has pointed out the cable between the power supply and the controller doesnt look very big and may be the cause of your issues, so I would start there

 

[Kitman]

Looking at this from a non expert perspective, You said that it was all working fine last year and no heat issues were present that you noticed, and now this year you have noticed that the one wire linking back is heating up. My suggestion is a simple one really. If all of the power supplies are exactly the same, same V and same watts, maybe try swapping over one of the power supplies, so put PSU 3 in position 1 or 2 and put the other PSU where PSU 3 was, swapping all wiring to match, if the same wire heats up then yes the wire may be too small, or you may have a short on one of the pixel strings, which is causing too much voltage to be drawn and heating up the wire, you could try disconnecting some of the strings and see if that makes a difference, and adding them back together in a different order, you might find that you have a short in one of the pixels and although it is displaying fine it might still have a fault.


Just my thoughts looking at this from an outsiders point of view and may be totally wrong.

 

[AussiePhil]

The ONLY reason it will get hot is because you have current flowing though the wire... now to find the reason.

Some thoughts.
There is little to no reason to connect PSU3 ground to the other 2 units, you will get much better load sharing by running the negatives out to the pixels.

you already have power coming into the ECGp12 from the pixels, why not power the board that way rather than the separate run to the power in connector.

I would have PSU1 supply one half and PSU2 supply the other half of the ECG

The wire gauge from PSU to the ECG looks far to thin....

 

[cdjazman]

I am not sure with the setup as that is how I bought the tree. The guy who I bought it from had done all the wiring.

As a note to the hot wire. I have removed the power supplies from the board and the wire is no longer getting hot. Maybe the screws I used attaching them to the board???? Not sure.

It may be a point to start from beginning and re-configure the wiring.

I can't get the lights to run in test mode at the moment and wondering if I have stuffed the board. I will see how I can test then separately.

I am pretty sure (but will recount when I get home ) that there is 150 pixels per strip and the tree has 20 strips. Last year I used the 3 power supplies in the configuration that it is now.

I will do up a new mudmap and see how I go with AussiePhils recommendations.

Thanks heaps for all the help. As usual the support within the group is outstanding.

 

[fasteddy]

So based on you using 20 strips spread over 3 power supplies and you using the 5vdc 2812B 30 LED/m strip then this is what im thinking

If you are running 6 strips per power supply then that cable definetly looks too small because if we look at the specs of the 150 pixel 5vdc 2812B strip we have a rating of 7.36 watts per metre which equates to approx 1.5 amps per metre at 5vdc, so each 5 metre strip will draw approx 7.5 amps. Now if we have 6 strips connected to a power supply then when we are using white colour then we could expect a total current for all 6 strips to be 45 amps at 5volts

So looking at that cable then it definetly looks too small for that load and even if it worked last year then i would still be changing the cable for a larger higher current rated cable.

 

[cdjazman]

Fasteddy,

Looking at my messages when i purchased the tree had the following information.

Strips are these; http://www.aliexpress.com/store/product/5m-led-digital-strip-DC12V-input-WS2811IC-256-scale-10pcs-IC-and-30pcs-5050-SMD-RGB/701799_568458133.html

and the following;

"The mega tree is 3.3m, so 33 (pixels) * 5 (lengths) = 165 pixels. 20 strips in the mega tree, so it consumes 4 channels on the P12R"

 

[fasteddy]

That changes things significantly because the 12v strip draws 5.76 watts per metre so at 12vdc it will draw approx 0.5 amps per metre for a total of 2.5 amps per 5 metre strip. So your load would be 3.3metres x 0.5amps = 1.65 amps per 3.3 metre length x 5 strips is 8.25 amps, so a lot different to using the 5vdc strip and so the cable you are using may infact be sufficient for that load depending on the size cable used.

 

[cdjazman]

ok cool.

would the size of the cable be printed on it or is there another way to work that out.

 

[fasteddy]

ok cool.

would the size of the cable be printed on it or is there another way to work that out.

To exclude the cable as being the issue then see if you can run single colours like red, green or blue. If you then have issues with mixing colours or white then i would say that its something to do with the cable.
If it still doesnt work with single colours at all then i dare say that something else is causing the issue because using a single colour should only draw approx 2.8 amps