I’ve got a question maybe for the @electrotechs?
Potentially need to drive a lot of LED strips again, but at 5V.
The strips are 2.4A per meter, and 2.5 or 2.8 meters long, so 6A
And theres probably 80-130 lengths 780A!!!
The way the data works they’re grouped into 6 lengths which is 36A, it just seems crazy to be dealing with over 20x 200W power supplies.
Is there a better way?
If is possible, I would use a constant current led driver , in this way you can have a wide ammount of voltages , that would help with the cable resistance as well.
I agree with @naxxfish lots of buck coverters and a higher line voltage.
A quick Google
It should reduce the posibilaty of the whole thing bursting into flames.
I would go for a 24 or 36 volt line voltage as at first inspection buck convertor seem to have a 36v max input voltage
Witch ever way you do it you are going to have to think about protection and fire risk as 720A is enough to set anything on fire . A larger number of smaller supplys dose have the advantage of limiting the maximum power to any point in the system. But you are also going to have to think about the input power factor of your psu
20 x 200w is 4 kw that is grown up power.
Each witch way round it is a lot of electricity
Bah, 4kW is a kettle and a toaster …
… on all day in an enclosed environment 
(it’s not going to draw 4kW constantly, not unless it’s 100% white the entire time)
4 kw big enough (16 to 25A at 240V) so that input power factor and harmonic output have to be thought about.
Remember a toster is has a pf of 1 and an en number. And is less than 13A
4kw is not huge but it is a bit more than the average progect . And I know from experience that 4kw in a enclosed space is a problem.
But if a white flash takes out the power because of harmonic output it will be a problem, we had that one at the royal wedding. Someone didn’t spec the brakers property and we realised under load it failed. And a lot of brakes had to be replaced asap , they were 6 kw psus
4kw is about 5hp , that is quite a lot of electricity, worst case scenario software hangs and it locks on 100% white …
It’d be 8 x 500W ATX power supplies (providing they’ve got a small load on the unused rail plus the required shorting pin 14 to ground to get it to start up)
Split it over two 16A circuits (or through a distro off one 32A), and you’d be in business.
Belt and braces, put a few decoupling caps near the power input to the strips, just in case a transient suddenly increases the load and the PSU can’t keep up.
Cooling obviously a concern, but if you happen have a bunch of unused 5 or 12V rails knocking about going spare, a few fans near a vent shouldn’t be too difficult!
I have never strapped that many at atx supplys together but should work and give 16 x12v
On the plus side atx supplys tend to go bang at the first sign of trouble and are cheaper than circuit breakers ( from CEF anyway ) .
A industrial 32A supplier should take it or a 16A 3 phase .
Witch was my point it is a bit more than you can plug into a 13A outlet .
So something like this would work: Ace Black 120mm Fan 550W comes to £16 or so.
If you went for the 5V output, you get 24A (120W) so you could drive 4 strips per PSU. If you did 12V you’d get a little bit more out of it, but the LED strips that take 12V appear to just be 5V strips with little buck converters stuck onto them at intervals (build quality probably not amazing, probably annoying to fix if they broke).
The specs say on the 230VAC input it draws a max of 10A. However, that’s assuming you’re using all of the rails at full capacity and drawing the full 550W. If you’re only drawing 120W, with 75% efficiency, you’ll have 160W at the input which gives you a nominal 0.7A (lets say 1A for safety).
That means that per 16A supply circuit, you could have 16 PSUs driving 64 strips. Two 16A supply circuits gets you 128 strips (is that close enough to 130?). Get a nice 32A to 16A distro board (with the appropriate RCDs fitted), plus a couple of 16A->13A distro boards. Or something that’ll take you directly from 32A to enough outlets
You could also run them not at 100% brightness (do the power balancing in software) to reduce the current requirements and subsequently heat for normal operation.
If you look how the professionals do it for things like the wall TV’s, its one SM-PSU for each set of panels. This keeps the current down (don’t want to create the worlds biggest welder) and adds a level of fault tolerance.
20x 200W power supplies may actually be the best/safest/most efficient solution.
I would agree with @joeatkin2 though, this will be Very noisy on the power side and should be driven from its own feed and breaker…
Courty
Yeah last time I did the one device one psu solution.
Cost is the only problem, it’s a lot of psus.
So we’re moving on with this…
I did some real word tests using a really decent multimeter at work.
This was with 6 meters of LED strip running video, the maximum as you can see was 2.8792 amps. It’s worth noting that this lower figure is probably because they are RGBW LEDs, so when the software wants white it uses the white LED chip rather than running the RGB chips at full power, so all 4 really aren’t ever likely to be on simultaneously.
I made an assumption from this that the peak power is going to be about 0.5A @ 5V per meter, and due to various technical limitations with controllers we’re probably looking at:
21x 2.4M strips = 25.2 amps @ 5V
18x 2.8M strips = 25.2 amps @ 5V
15x 3.4M strips = 25.5 amps @ 5V
I’m thinking of using the Meanwell SP-150-5 which is 30A @ 5V with a power factor of 0.93 at 230V which seems pretty good from my limited knowledge.
The great thing about this layout is that the number of controllers directly equals the number of power supplies so it’s nice and modular.
Anyway it’s moving along slowly.
