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

Blowing fuses on distro board with mega tree

Discussion in 'Power Supplies' started by tooms, Nov 6, 2017.

  1. tooms

    tooms Apprentice Elf

    Joined:
    Jan 2, 2015
    Messages:
    74
    Likes Received:
    10
    Location:
    Kalgoorlie
    So I've gone ahead and wired up my first mega tree, it was all going great until I started playing around Vixen and went full white on a few things and started popping fuses. I'm using 2 x DC Supplies with 2 x F8 distro boards so I can spread the load over both supplies, the tree is small with only 12 x 100 pixel strings of 12v 2811. I've drawn a diagram of how it's put together, unfortunately I suspect the distro board with it's 5 amp fuses isnt enough, and I've thought about putting bigger fuses in them but I believe the whole board is only rated for 5 amp outputs, diagram only shows the first 6 strings, the same fuses powering up strings 2,3,4 & 5 blew today on the set of 6 six strings.

    Any idea's on how I can improve it are welcome.

    [​IMG]
    View: https://imgur.com/a/8d93f
     
  2. David_AVD

    David_AVD Bite my shiny metal ass!

    Joined:
    Jun 12, 2010
    Messages:
    3,474
    Likes Received:
    60
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    Each set of 100 pixels would draw 5A - 6A on full white, so no surprise that 2 sets of 100 are blowing a 5A fuse.

    Also, do you really have the V+ line connected at the top at each direction change? (you should not)
     
  3. AAH

    AAH I love blinky lights :) Community Project Designer

    Joined:
    Dec 27, 2010
    Messages:
    2,586
    Likes Received:
    32
    Location:
    Eaglehawk
    Find Me On:
    1200 pixels will be drawing pretty much 66A at full white so you'll be pushing typical 350W supplies to the limit as well. Depending on the number of fuses protecting each string you may not have enough capacity. Each pixel is going to be about 55mA on full white so each string of 100 will be 5.5A. If you had 1 fuse per string of 100 it's unlikely you'll ever blow a fuse as the time for a fuse to blow at 10% over it's rated capacity is likely to be in the hours rather than the multiple seconds at a time it's likely to be while testing or during a show. If you've got more than 100 per fuse then it's almost a given that you'll blow fuses at full white.
     
  4. videoman3857

    videoman3857 Full Time Elf

    Joined:
    Apr 21, 2016
    Messages:
    233
    Likes Received:
    33
    Location:
    Glass House Mountains
    I'm just learning this so don't take me as gospel
    I believe the ws211 has a current draw of 0.060 amps per pixel.
    0.060 x 100 = 6 amps per String 5 amp fuse = blown.
    6 amps x 12 strings -= 72 amps.
    72 amps x 12 volt = 864 watt + 20% for 80% power draw = 1036 Watts
    1036 watts / 350 watt power supplies = 2.96 ergo 3 power supplies.
    I would have a power supply every 4 strings.
    Like I said. I am new at this.
    This is my understanding.
    I know not if I am right or wrong and no doubt the experienced will chime in on this.
     
  5. videoman3857

    videoman3857 Full Time Elf

    Joined:
    Apr 21, 2016
    Messages:
    233
    Likes Received:
    33
    Location:
    Glass House Mountains
    Holly dooley.
    2 more posts pop in before mine as I am typing my comment out
     
  6. OP
    OP
    tooms

    tooms Apprentice Elf

    Joined:
    Jan 2, 2015
    Messages:
    74
    Likes Received:
    10
    Location:
    Kalgoorlie
  7. OP
    OP
    tooms

    tooms Apprentice Elf

    Joined:
    Jan 2, 2015
    Messages:
    74
    Likes Received:
    10
    Location:
    Kalgoorlie
    Yep .. I think I might be a bit light on power supplies and low on fuse sizing, which is a bit of a bummer as I have my control box all setup how I thought it was going to be good, will add another supply and look for another distro board option.


    [​IMG]
    [​IMG]
     
    videoman3857 likes this.
  8. videoman3857

    videoman3857 Full Time Elf

    Joined:
    Apr 21, 2016
    Messages:
    233
    Likes Received:
    33
    Location:
    Glass House Mountains
  9. videoman3857

    videoman3857 Full Time Elf

    Joined:
    Apr 21, 2016
    Messages:
    233
    Likes Received:
    33
    Location:
    Glass House Mountains
    David could you please give a reason why not to have the + connected in the direction change.
    I thought it was ok to connect for the direction change for each run from each PSU supply
    Not ok to link between the PSU supplies as per this schematic posted by Roosta

    [​IMG]
     
  10. darylc

    darylc Full Time Elf Global Moderator Generous Elf

    Joined:
    Dec 8, 2012
    Messages:
    365
    Likes Received:
    51
    The problem is that if one fuse blows, some current may move to other paths and blow the rest of your fuses
     
  11. David_AVD

    David_AVD Bite my shiny metal ass!

    Joined:
    Jun 12, 2010
    Messages:
    3,474
    Likes Received:
    60
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    Any fused section must have only one current source; via that fuse. If you connect the tops , the current will flow from adjacent strings as well as via the intended (fused) path.
     
  12. David_AVD

    David_AVD Bite my shiny metal ass!

    Joined:
    Jun 12, 2010
    Messages:
    3,474
    Likes Received:
    60
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    That DIYC PI diagram is just plain wrong. There most certainly should not be the circular route shown there.

    The positive wire in that diagram has two different fused sources; one from the controller board and another directly via the power supply.

    For a PI arrangement with fuses, you should break the positive current path somewhere so that the fuses are independently feeding their own sections.
     
  13. the grinch

    the grinch I guess I could use a little social interaction

    Joined:
    Jun 23, 2013
    Messages:
    397
    Likes Received:
    30
    Location:
    angle vale s.a.
    As many know im a little bit different in how I see and do things ! And touch wood haven't blown anything up etc etc yet ! I don't get over enthusiastic with fusing everything .our display consists of 12v 2811s nodes and strips and some 12v 3528 dumb strips don't use 5v rough estimate around 80 strips or lengths . I always ensure I have enough power for each element only use cheaper power supplies 12v 33a ebay order and keep a spare or two just incase ! my power injection points are generally at start of first strip and start of the third strip so every 10 m basically so as not to rely on too much power through the controller has never been any issues also have brightness turned down on controller usually between 25% and 40% as the brightness is overwhelming but ensure there is enough supply for 100% if required . never had a blown fuse yet ! Probably cause I don't have too many lol also it is another expense . I check double triple check everthing is wired correctly and most importantly safe and ensure I cannot accidentally plug the wrong thing in the wrong place ! My biggest fear would be a power surge from the mains or lightning strike as fing experienced couple years back ! Unfortunately fuses wont save us in such a scenario ! But once again we all see and do differently
    So thats my story and works for me !
    Good luck mate hope you find you're way !
     
    Last edited: Nov 7, 2017
    Roosta likes this.
  14. OP
    OP
    tooms

    tooms Apprentice Elf

    Joined:
    Jan 2, 2015
    Messages:
    74
    Likes Received:
    10
    Location:
    Kalgoorlie
    Thanks all, have plenty of food for thought now
     
  15. OP
    OP
    tooms

    tooms Apprentice Elf

    Joined:
    Jan 2, 2015
    Messages:
    74
    Likes Received:
    10
    Location:
    Kalgoorlie
    I suspect this is what was going on, I was only blowing fuses with a vixen curtain effect, each string being fully white and then moving to the next, some kind of in-rush current was going back the other way I think.

    I've ended up re-wiring the whole thing and using a 16 port falcon under it and just have each string on a single port with no power injection, seems simpler and I'm running out of time already this year so decided to just simplify it.
     

Share This Page