Author Topic: Fusing the power supply input  (Read 586 times)

Offline aERonAUtical96

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Fusing the power supply input
« on: October 03, 2018, 01:28:40 PM »
How are you fusing the AC side of the power supply input?

Offline Bwinter

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Re: Fusing the power supply input
« Reply #1 on: October 03, 2018, 01:54:23 PM »
Shouldn't this be handled at your breaker-box?

Offline aERonAUtical96

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Re: Fusing the power supply input
« Reply #2 on: October 03, 2018, 03:25:06 PM »
Yes.  And this specific outlet is GFCI.  But here is text from doityourselfchristmas... not saying it is correct or incorrect.  It makes sense, but just wasn't sure what other did.

Fuses should be installed in several places:
    • Install AC line fuses between your wall outlet and your Power Supplies
    • Install Fuses anywhere you join a larger wire to a smaller wire for power distribution
    [/list]

      Offline sklankowski

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      Re: Fusing the power supply input
      « Reply #3 on: October 03, 2018, 03:47:23 PM »
      I use these.  Working with 240VAC on power supply.  Definite must have. 
      https://www.mouser.com/ProductDetail/571-W57XJ2A22B10-20M

      Offline rstehle

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      Re: Fusing the power supply input
      « Reply #4 on: October 03, 2018, 05:40:16 PM »
      Yes.  And this specific outlet is GFCI.  But here is text from doityourselfchristmas... not saying it is correct or incorrect.  It makes sense, but just wasn't sure what other did.

      Fuses should be installed in several places:
        • Install AC line fuses between your wall outlet and your Power Supplies
        • Install Fuses anywhere you join a larger wire to a smaller wire for power distribution
        [/list]

          IMO, it is not necessary to do any of those things, assuming that your controller has intput and output fuses built in to it.  Most every controller and power distro board already does.

          Offline k6ccc

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          Re: Fusing the power supply input
          « Reply #5 on: October 03, 2018, 08:53:45 PM »
          Yes.  And this specific outlet is GFCI.  But here is text from doityourselfchristmas... not saying it is correct or incorrect.  It makes sense, but just wasn't sure what other did.

          Fuses should be installed in several places:
          • Install AC line fuses between your wall outlet and your Power Supplies
          • Install Fuses anywhere you join a larger wire to a smaller wire for power distribution

          IMO, it is not necessary to do any of those things, assuming that your controller has intput and output fuses built in to it.  Most every controller and power distro board already does.
          I'm going to partially disagree with rstehle.  First of all, his statement that most controllers and power distro boards have input fuses is false.  I don't know of ANY controllers that have input fuses (doesn't mean there aren't, but none that I have used or looked at docs for).  As for the need to fuse between the power supply and controller may well depend on what that supply is powering. 

          As for some of the other points, it may depend on the installation.  Anytime the wiring gets smaller than the total output capability of the power supply, there should be a fuse.  For example, you have a 70A 5V power supply that is powering a pixel controller, and also a Raspberry Pi.  Good bet that the wiring going to that Pi can't handle 70A.  It should be fused. 

          Different situation.  For example, if you have a 20A 120V AC circuit that is supplying power to a half dozen of the typical 350 watt power supplies that so many of us use, you really should fuse each supply individually on the input.  If you have one of those power supplies fail in a shorted condition, it may very well catch fire before that 20A breaker trips.  If those power supplies are together (such as in one box), you just burned down all six supplies instead of just one popping it's fuse.  It also means that all six of the power supplies loose power.

          Always have fuses between power source (pixel controller or Power Injection distribution) and pixel strings.  Of course most (if not all) pixel controllers have output fuses.

          Using LOR (mostly SuperStar) for all sequencing - using FPP only to drive P5 and P10 panels.
          Jim

          Offline rstehle

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          Re: Fusing the power supply input
          « Reply #6 on: October 03, 2018, 10:37:27 PM »
          Yes.  And this specific outlet is GFCI.  But here is text from doityourselfchristmas... not saying it is correct or incorrect.  It makes sense, but just wasn't sure what other did.

          Fuses should be installed in several places:
          • Install AC line fuses between your wall outlet and your Power Supplies
          • Install Fuses anywhere you join a larger wire to a smaller wire for power distribution

          IMO, it is not necessary to do any of those things, assuming that your controller has intput and output fuses built in to it.  Most every controller and power distro board already does.
          I'm going to partially disagree with rstehle.  First of all, his statement that most controllers and power distro boards have input fuses is false. I don't know of ANY controllers that have input fuses (doesn't mean there aren't, but none that I have used or looked at docs for).  As for the need to fuse between the power supply and controller may well depend on what that supply is powering. 

          As for some of the other points, it may depend on the installation.  Anytime the wiring gets smaller than the total output capability of the power supply, there should be a fuse.  For example, you have a 70A 5V power supply that is powering a pixel controller, and also a Raspberry Pi.  Good bet that the wiring going to that Pi can't handle 70A.  It should be fused. 

          Different situation.  For example, if you have a 20A 120V AC circuit that is supplying power to a half dozen of the typical 350 watt power supplies that so many of us use, you really should fuse each supply individually on the input.  If you have one of those power supplies fail in a shorted condition, it may very well catch fire before that 20A breaker trips.  If those power supplies are together (such as in one box), you just burned down all six supplies instead of just one popping it's fuse.  It also means that all six of the power supplies loose power.

          Always have fuses between power source (pixel controller or Power Injection distribution) and pixel strings.  Of course most (if not all) pixel controllers have output fuses.

          I stand corrected.  That's what I get for assumiong........  The Sandevices e682 has an input fuse, but the Falcon's don't........  why not David ??????

          Offline k6ccc

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          Re: Fusing the power supply input
          « Reply #7 on: October 03, 2018, 10:56:29 PM »
          I stand corrected.  That's what I get for assumiong........  The Sandevices e682 has an input fuse, but the Falcon's don't........  why not David ??? ???
          Um, no.  Neither the SanDevices E6804 (I have two of them running my landscaping show as I type this), nor the E682 (I run four of them for Christmas - one of which is sitting here on my desk) has input fuses.  The only fuses are one for each string output, and a 2A fuse for the board power itself.  There is no 40 A fuses on the two inputs.  A short on the PC board traces on the power buss will keep going until something burns up or the power supply fails.
          I believe the Falcons are the same way.  A fuse for each string output, and a fuse for the board power itself.  The on board power buss is not protected.

          Offline aERonAUtical96

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          Re: Fusing the power supply input
          « Reply #8 on: October 04, 2018, 04:58:15 AM »
          Fusing between the power supply and the boards and from the boards out to the pixels, including injection, is fairly easy with DC fuse blocks, etc.  I'm really curious about the AC side into the PS.  On my current PS, I don't fuse on the input side.  I know I would blow a PS because of that, but don't know of the options.

          Offline jnealand

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          Re: Fusing the power supply input
          « Reply #9 on: October 04, 2018, 08:47:11 AM »
          The AC side of your power supply surely has a fuse in your house electrical box.

          In 12 years of doing animated light shows I have never, ever added any extra fusing and I have never had any problem.  Fuses are insurance and it is a personal choice for doing it.  In my personal experience I have never had an issue, but I also never load up controllers or even a single output close to their theoretical max.  In general I also do not use power injection as I have only gone over 120 12v nodes per output on except on things like matrices, chromabulbs and spinners.  YMMV

          Jim Nealand
          Kennesaw, GA all Falcon controllers, all 12v Master Remote Multisync with Pi and BBB P10 and P5

          Offline k6ccc

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          Re: Fusing the power supply input
          « Reply #10 on: October 04, 2018, 08:58:49 AM »
          Fusing between the power supply and the boards and from the boards out to the pixels, including injection, is fairly easy with DC fuse blocks, etc.  I'm really curious about the AC side into the PS.  On my current PS, I don't fuse on the input side.  I know I would blow a PS because of that, but don't know of the options.
          Let's face it, LOTS of people do not pay enough attention to fusing.  And they get away with it almost all the time, which reinforces the belief that they should not have to worry about it.  Until something bad happens.  I am making some changes to the power for my pixel tree because of a tree expansion.  As part of testing some new pixels last week, one of the commonly used 350 watt 12V Chinese power supplies failed when I plugged it in.  Kinda reminded me that when I put several of them in a box on the back of the tree, I really should add fusing since the supplies don't have any inlet protection.  I don't know if I will fuse the connection between each power supply and the pixel controllers, but it will be a single PS out to a each input on the controller.  We'll see...  The power to the pixel strings are fused - both from the controllers and the Power Injection.
          I see jnealand replied while I was typing this saying he has always gotten away with it - as have I.  His description of fuses as insurance is very good...

          Offline k6ccc

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          Re: Fusing the power supply input
          « Reply #11 on: October 04, 2018, 03:09:15 PM »
          The AC side of your power supply surely has a fuse in your house electrical box.
          Just a word of warning.  Draw 25 amps through a 20 amp breaker in your house breaker panel sometime and see how long it takes to trip.  It will scare you.  For most breakers it will be measured in minutes - maybe quite a few.  How do you get 25 amps in a fault, you ask?  How about a substantial short in a power supply that is hanging on the end of a semi-long length of 18 gauge SPT-1.  Enough resistance in the wire to limit the current pretty well.  Draw 25 amps through that SPT-1 for very long and it's gonna get REALLY hot!  Granted that the run of SPT-1 will work just fine as long as the power supply is behaving (the typical 350 watt power supply so many of us use will max out at just over 3 amps).  But it can't handle a substantial fault current.  That goes back to the last item on the list near the top of this thread.

          Note, I'm not trying to be argumentative or scare people, but just to make people think about some electrical safety.  The last thing any of us want is to have your show shut down because it started a fire in your house...  Just because you got away with something that was sub-standard many times does not make it right...  BTW, I am as guilty of not fusing the individual power supply inputs as well.  With my pixel tree rebuild (which will have five 350 watt power supplies in a box), it is something I intend to fix...


          The other thing I will point out is why I look at this kind of stuff so seriously.  Professionally I run a public safety two way radio system.  We have several dozen police and fire agencies using the system.  We fully understand that under the wrong set of circumstances, if the radio system fails, someone can die.  Therefore, we take reliability VERY seriously.  Part of that is electrical safety, reliability and redundancy.


          Offline pixelpuppy

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          Re: Fusing the power supply input
          « Reply #12 on: October 06, 2018, 05:55:02 AM »
          ...since the supplies don't have any inlet protection...
          (the typical 350 watt power supply so many of us use will max out at just over 3 amps).  But it can't handle a substantial fault current. 

          Actually, the typical 350 watt power supplies do have inlet protection.   Open one up and you will find a 3A fuse AND a current-limiting thermistor right at the AC power input to the circuit board.  These parts are not easily accessed but they are there for inlet protection.   Don't ask me how I know  ;D

          « Last Edit: October 06, 2018, 06:20:09 AM by pixelpuppy »
          -Mark

          Offline k6ccc

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          Re: Fusing the power supply input
          « Reply #13 on: October 06, 2018, 12:09:48 PM »
          Actually, the typical 350 watt power supplies do have inlet protection.   Open one up and you will find a 3A fuse AND a current-limiting thermistor right at the AC power input to the circuit board.  These parts are not easily accessed but they are there for inlet protection.   Don't ask me how I know  ;D
          Nice to know.  Never had one apart.

          Offline tbone321

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          Re: Fusing the power supply input
          « Reply #14 on: October 08, 2018, 01:05:05 PM »
          The AC side of your power supply surely has a fuse in your house electrical box.
          Just a word of warning.  Draw 25 amps through a 20 amp breaker in your house breaker panel sometime and see how long it takes to trip.  It will scare you.  For most breakers it will be measured in minutes - maybe quite a few.


          If you can pull 25A thru a 20A breaker for more than about 1 second, you have a defective breaker and the magnetic trip for the breaker has failed.  Heck, even pulling a steady 19A from a 20A breaker should cause it to trip in a few minutes.  That is due to the thermal trip protection of the breaker and is the reason for the 80% rule.  The breaker being the fuse or protection for your power supplies input side is also completely false.  The breaker is in place to protect the outlet and wiring between the breaker and the outlet, not the device(s) plugged into the outlet.  Putting a fuse on the input side of a PS doesn't really do all that much and in most cases is simply not needed.  Putting fuses on the output side of the supply is a good idea and will protect the supply from excess current draw that can overheat or damage the supply. 

           

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