1. New to Christmas lighting? Get started with the AusChristmasLighting 101 Manual:
    auschristmaslighting.com/wiki/AusChristmasLighting-101

Help req with power

Discussion in 'Power Supplies' started by Vertigo_uk, Dec 25, 2017.

  1. Vertigo_uk

    Vertigo_uk New Elf

    Joined:
    Dec 9, 2017
    Messages:
    8
    Likes Received:
    0
    Hi

    Doing some planning for next year and currently looking at power supplies.

    I have calculated approx 4500 at 30/m or 9000 at 60/m. Approx 150m total maybe more dependent if I go for a 16 or 32 mega tree.

    This will be either 5v/12v 2811 with a mix of strips and strings. not decided which voltage yet.

    What I have calculated is

    5v
    4500@0.3w = 1350w 4500@60ma = 270a
    9000@0.3w = 2700w 9000@60ma = 540a

    12v
    4500 @0.8w =3600w 4500@66ma = 297a
    9000@0.8w = 7200w 9000@66ma = 594a

    First of all is this calculated correctly?

    Next obviously I will need a few power supplies and provide varying levels of power injection dependent on 5/12v? How many do you think I will need?

    I will be running them all from a Falcon16v3 controller. Does power have to go through the controller or can it be direct to the strips/strings then just control wire from board.

    How would I power this all from 240v mains I’m thinking I may need to have a new breaker board put in would I be able to power this new psu board from a 32a breaker or will it need to come off a 60a.

    I’m rather confused between the input amps and output amps. How would I convert this to 240v so I can find the true draw on the mains?
    For power injection is it a case of running a wire in parallel from one output of psu to all strips every metre or 2? Or is there a better method?

    Any other considerations you can think of?

    Sorry for all the questions but don’t want to blow anything up and want it to look good and reliable lol.

    Merry Christmas all
     
  2. AAH

    AAH I love blinky lights :) Community Project Designer Generous Elf

    Joined:
    Dec 27, 2010
    Messages:
    2,854
    Likes Received:
    162
    Location:
    Eaglehawk
    Find Me On:
    The calculations are about right. Typically pixels are about 55mA each. In practice they are often lower than that but it's better to work on the maximum load value.
    The 5V power of 270A @ 5V is 1350W of output power. The power supplies are typically 85-90% efficient so the input power is typically going to be about 1600W which is well under a typical 240V outlet power. The choice of power supplies and how much current they draw is dependent upon whether they have power factor correction. Having it reduces the input power and your power bill.
    The 12V power will be overrated as it's more likely to be 55mA each rather than 12V. As there are 3 times the number of leds per pixel you may end up with a lower number of pixels. There are also a few pixel types like INK1003 and others that the strip is powered from 12V and is stepped down to 5V.
    The power injection is a matter of providing extra copper to both the positive and negative rails at points along the pixel run to compensate for voltage drop. This can be done by having the power supplies close to the pixels or having heavy duty cable running from a central point out to the pixels. If the pixel run is particularly long as can happen if you take benefit of the multi universe outputs on some controllers then it can be advantageous to have another power supply supplying power to the 2nd half of the strip/nodes with the 5V or 12V broken so that the 2 power supplies aren't both sharing a positive connection.
     
  3. scamper

    scamper Senior Elf

    Joined:
    Jan 5, 2014
    Messages:
    890
    Likes Received:
    100
    Location:
    collie
    Find Me On:
    In layman's terms, and VERY rough calculations, the output watts will be similar to the input watts, then divide by the mains voltage to give your mains current, so yes you are well under a typical power outlet.
    Also, unless you run your show at full white at full brightness, you are never likely to draw max current. Because of the intensity of LED"s a lot of people (myself included) set the brightness at the controller to a max level, in the case of my tree and matrix, it is 50% and you cannot see any visible difference.
    In saying that, when you have many power supplies of this size hooked to a typical power outlet, at initial switch on, you get a huge surge of inrush current that has been known to trip some peoples circuit breaker/ RCD. so keep that in mind when setting up.
     
  4. OP
    OP
    Vertigo_uk

    Vertigo_uk New Elf

    Joined:
    Dec 9, 2017
    Messages:
    8
    Likes Received:
    0
    That’s brilliant. Thanks. At least I know I don’t need to get an electrician in to install a dedicated breaker lol. Will go on the hunt for psu now lol. Didn’t realise how much of a headache this all was and not even started yet lol. It will be worth it in the end.
     
  5. OP
    OP
    Vertigo_uk

    Vertigo_uk New Elf

    Joined:
    Dec 9, 2017
    Messages:
    8
    Likes Received:
    0
    Managed to source a few 48v eltek flatpak in a 2u cabinet. 98.6% efficient These seems to be an awesome solution. 240v in 48v out 2000w psu x 4. Built in busbar for positive and negative. Built in control panel with alarm readout and voltage wattage temp etc it will power share between the psu so if 1 2 or even 3 fail there is still plenty of juice to power it all. It can all run on a 60a mcb It even supports battery backup if I wanted it to lol. May just get one to power the house haha. Batteries last between 2 - 8 hours depending on load.

    Will then use a 48v to 5/12v converter for each pi point. Beauty of this is I can use cat 5 for pi

    I haven’t tried yet but may even be able to get my hands on a alifabs street cabinet to house it all in. Lockable and waterproof

    Rectifier
    http://www.eltek.com/detail_products.epl?id=1123903

    Power system
    http://www.eltek.com/wip4/download_doc_647.epl?id=6845

    Cabinet (would even be happy leaving my laptop in it lol these things are like safe’s (one on the left)
    https://legacy.pedroc.co.uk/manx_telecom_microcell.htm
     
    Last edited: Dec 31, 2017
  6. David_AVD

    David_AVD Bite my shiny metal ass! Community Project Designer Generous Elf

    Joined:
    Jun 12, 2010
    Messages:
    3,741
    Likes Received:
    173
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    Don't forget to fuse the outputs according to the wire sizes used. Otherwise you're talking about a major fire hazard.
     
  7. OP
    OP
    Vertigo_uk

    Vertigo_uk New Elf

    Joined:
    Dec 9, 2017
    Messages:
    8
    Likes Received:
    0
    All built in to the psu with breakers on each output. But I agree will add an inline fuse per wire rated to wire size if anything just to protect the wires. Should be ok at 48v but better to be safe than sorry.
    Thanks

    lll
     
  8. David_AVD

    David_AVD Bite my shiny metal ass! Community Project Designer Generous Elf

    Joined:
    Jun 12, 2010
    Messages:
    3,741
    Likes Received:
    173
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    If the 48V output can supply 40A or so, you most definitely should fuse the individual feeds if those cables are rated for less than 40A.
     
    Vertigo_uk likes this.
  9. OP
    OP
    Vertigo_uk

    Vertigo_uk New Elf

    Joined:
    Dec 9, 2017
    Messages:
    8
    Likes Received:
    0
    Yeh that’s what I though lol. It’s capable of 63a so definitely need fuses lol.
     
  10. i13

    i13 Senior Elf

    Joined:
    Jul 5, 2013
    Messages:
    802
    Likes Received:
    21
    I have only used these DC-DC convertors stepping down from 31V to 12V and 5V.
    http://www.aliexpress.com/store/pro...tableDC1-25-36V-output/701799_1659517282.html

    They work well enough though I found that their output voltage increases when they're under load. I've only tried measuring their output under load when it should be 12V. darylc also had trouble with a different convertor that gave out 7V instead of 5V. I think they're a good idea but it is best to measure their voltage output when they're under load and not assume that it will be the same as when there's no load.

    The 5V versus 12V question is one for which there's no perfect answer. 12V nodes and 12V strip are wired differently to each other too. In 12V nodes, the extra power is wasted in a resistor while in strips, there are 3 RGB LEDs per pixel which use this power more efficiently and help reduce the required current. A lower current means less voltage drop and 12V means any voltage drop that occurs has a smaller effect because it is a smaller percentage of the correct voltage. For these reasons, I use 12V strip in applications like roof outlines where the pixel density can be low (controllable in 10cm sections) and long runs of pixels are required. I use 5V strip when I want every single LED to be individually controllable. I have 5V nodes but no 12V because I prefer to inject power instead of wasting it.

    Due to power injection, it is possible to have 5V and 12V pixels running on the same controller.

    Summing it up, 5V is a good choice when you want a large number of pixels in a small area (e.g. a megatree or matrix). 12V is a good choice when you want a small number of pixels in a large area (e.g. a roof outline). This is my opinion anyway.
     
    B4IGO likes this.

Share This Page