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Im not a newbie but still feel like 1 with this question


Christmas_time_karl_UK
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Christmas_time_karl_UK

After dusting of my LOR storage box I realised I have forgotten quite a bit from last year, so I thought I would post this thought on my mind to have it corrected or affirmed.

I have a CTB16PC which I brought last year and a 16 channel kit board I brought last year.

The CTB16PC can handle a max of 30amps (15 each bank) (with regular heat sink & dual power supply) over its two banks and each channel can handle 8 amps with the regular heatsinks...thus I can only "switch on" 1 full channel using 8 amps and another channel using 7 amps? If I used 16 Amps on 1 side this would blow the fuse?



Thanks

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You are correct.

Would 16a blow the fuse? My memory is faded, but I don't think it will for a short period. Any long term use at that rating could blow the fuse, I would suspect.

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I know in electrical design, they only want you to go up to about 80% of a rated capacity for safety and other reasons I just don't know.

It has been my experience, though not with LOR, when fuses get to their rated amperage, they will blow. There is not much room for extra voltage unless you have a "slo-blo" fuse.

I have seen a fuse save itself (once or twice) and cause a $$$ motor starter to burn out. After that, I quit using "slo-blo" fuses.

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I am not sure the board is designed to withstand the amperage. And if it were, you would need to change the power supply cords servicing the units to be able to handle the load.

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It is my understanding the boards can handle 20amps but they are shipped with 15amp fuses. I've had to pull all my 15amp fuses and put in 20's for this year. Remember you should leave youself some room, when things get wet the amps go up also if somethings been chewing on you display you want the fuse to bolw before it damages the board. I'm only pulling 16amps with everything full on and I'm not adding more. I'm running 79 channels with 72,000 lights and LOR has not broke out in a sweat yet. Contact LOR and they can send you the fuses or do as I did and buy your own.

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James Shelby wrote:

It is my understanding the boards can handle 20amps but they are shipped with 15amp fuses. I've had to pull all my 15amp fuses and put in 20's for this year. Remember you should leave youself some room, when things get wet the amps go up also if somethings been chewing on you display you want the fuse to bolw before it damages the board. I'm only pulling 16amps with everything full on and I'm not adding more. I'm running 79 channels with 72,000 lights and LOR has not broke out in a sweat yet. Contact LOR and they can send you the fuses or do as I did and buy your own.



The PC boards themselves are rated for 20 amps, just like all the other LOR boards. However, the PC enclosure does not have much room inside the box to cool off the board if it was constantly running at 20 amps a side. If the fuses were swapped out for 20 amps fuses, you "could" run the board over 15 amps a side, but not for long and not without letting it cool off.


This is also assuming you have the more unusual 20 amp circuit and power cords rated for 20 amps.
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Almost all fuses can go over their rated current for short peorids of time. The CTB16PC card can handle 20 amps(per side) BUT only for short durations. The CTB16D cards are designed to handle the full 20 amps continiously.

Never use a slow blow fuse with the LOR controllers. You want the fuse to blow as quicly as possible when you have a short circuit... The fast acting fuses will sometimes save the triacs when you have a short circuit.

I would not be concerned with a 16 amp load on the fast acting 15 amp fuse if it will only be at 16 amps for short peorids.

The rule of running equiptment at 80% rating is a good one. However when we designed the LOR equiptment we added a safety margin into their ratings.

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  • 4 weeks later...
Christmas_time_karl_UK

How short is this duration you speak of? Please could I arrange for you to send some bigger fuses as well as some spares for my 16 Channel Kit card I brought from you in 2006?

Thankyou

Karl

LightORamaDan wrote:

Almost all fuses can go over their rated current for short peorids of time. The CTB16PC card can handle 20 amps(per side) BUT only for short durations
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Donald Puryear

Keep in mind the fuse is designed to protect the board. The triacs may be able to handle 8 amps each but the solder paths on the board would never withstand 64 amps. I once assembled a light sequencer kit that had the same restrictions. I removed the tracs from the board, mounted them on larger heatsinks, wired then with larger wire from the triacs to the input and output cables. Thus allowing me to push the system to 50 amps.

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We had a discussion at the FL mini concerning the 80% rule and I had to question some of the reasoning when it pertains to LOR.

Here is what I think and have found to be true. With only one exception.

The exception first: if you are using your LOR for a pure static display then careful attention must be given to total amps and maybe 80% would be correct. However, as Dan has stated they are designed to handle all 20 amps on each side.

Now my theory.
How many times do you run every single light on your control board for more than a couple of seconds? How many times do you use more than 8amps on a certain channel. If you are talking mini lights then that is a ton of lights. Floods and the C7 and C9 lights are different.

My point is, if your total light count is a little over the 20amps per side chances are that you will not have an issue. The reasoning is that seldom if at all do you have all of the lights on. Therefore, less than the 20amps per side would be used at any one time. I would not however press the 8amp per channel rule.

The other interesting thing is the actual circuits you connect your controllers. Seldom will you hit the 20amp or 15amp level. However, if you do, my guess it would be less than a second or two at the most. Therefore, there would be no tripping of the breaker.

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I saw a show on TV last week about how they made circuit breakers. It really surprised me when they said that a breaker is designed to pop when it exceeds 35% of it's rating. So, a 20 amp breaker would trip when it was pulling about 27 amps. That was kind or surprising to me, and a bit un-nerving.

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