Sizing service for LED Billboard

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all you have on the service is LED lights ? sounds like a homework question. dynomite !
 
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well I am really not sure were to begain, if some one could give me some sort of formula :confused:I will give it a shot
 
joez, you have us at a bit of a disadvantage. We are here to discuss and offer assistance, but, often times "students" come here just to get answers and that's why we ask "what did you get" first.
Your profile says "electrical contractor" and most contractors would know the basics enough to give an plausible answer to obtain verification.
Are you, as stated, an electrical contractor ?
 
Joe,
Hope you are doing good, I looked at the plans of that LED. It was not drawn by anyone with a electrical back ground. Where they are messing you up is were it says 120/208 3- phase 2 hot 1 ground no nuetral. I believe that is for the branch circuits, keep asking all the question you want some of will help.
formula is I= watts/(E x 1.732)
 
joez710 said:
120/208 3 Phase
100,640 Total System Watts:confused:
Click to expand...

Lemuel said:
keep asking all the question you want some of will help.
formula is I= watts/(E x 1.732)
Click to expand...

Meaning you didn't like the way his question was answered?

You are new here and probably don't know that we don't just jump to answering questions that appear to be study or homework, we want the person asking to make an effort.

As Augie said, the question is pretty basic and seems to be odd for an EC to be asking

Roger
 
Joez, If you care to continue the discussion, the answer will depend on the nature of the load. If, as Lemuel suggests, the load is composed of single phase components, then the load per phase will have to be determined from the individual loads and not the total as it will not necessarily be evenly distributed.
In addition, if it as as suggested, a single phase-no neutral load- you might want to verify the design voltage. The LED units I have seen are 240v and required a buck-boost transformer to operate correctly.
Therefore, depending on the actual nature of the load, the required service size will vary.
The correct answer will require more input information.
 
No, I am not saying that at all, I have meet Joe before and know he is a repected electrical contractor. I just had a chace to look at the plans and it like nothing you have ever seen and it stated the power source as "120/208 3-phase,2 hots,1 ground, no nuetral" I have never seen this but that doesn't mean it s not out there. I have been in this business a long time and learn new stuff about it everyday. Some people think I ask simple QUESTIONS
 
Lemuel said:
No, I am not saying that at all, I have meet Joe before and know he is a repected electrical contractor. I just had a chace to look at the plans and it like nothing you have ever seen and it stated the power source as "120/208 3-phase,2 hots,1 ground, no nuetral" I have never seen this but that doesn't mean it s not out there. I have been in this business a long time and learn new stuff about it everyday. Some people think I ask simple QUESTIONS
Click to expand...

sorry, I have no idea what your post means other than certifying that "Joe is a contractor".
No one here would want to give him bad information, but the nature of his question might lead to that.
If his service is 3 phase 208/120 and the load is 100,640 watts the service size can vary greatly depending on the nature of the load.
Are the loads single phase or three phase can make a huge difference.
I have seen a lot of LED billboard installations with a 240 volt single phase load requirement (multiple loads) and the size service needed obviously depends on the distribution of those loads.
The service required for a 100,000 watt 3 phase load will not be the same as the one for (2) 50,000 watt single phase loads being operated off a 3 phase service.
 
"120/208, 3 phase, two hots, one ground, no neutral" implies a single phase 208 volt load fed from a 3-phase 208 volt service. If the load is 3-phase, 3 hots are needed.

If the single phase assumption is correct, the load is I= watts/208V= 100,640/208 = 484 amps. Add 125% = 604 amps. Since it's more than 600A you jump to an 800 Amp service.

The data doesn't add up. Single phase 208V 800A service?? I reccommend you ask some questions on how the system is wired.
 
The only thing I'd add is that a 100KW LED sign on three phase is going to need one to closely look at the neutral currents, as thats almost certainly a totally non-linear load.

But that probably comes later in the course :)

And a 100KW LED billboard is going to be "large" as billboards go; most LED displays are figured at under 1KW/sq meter, so thats 100 sq metres of display...

Edited to note that most of these sorts of displays are modular, made up of "tiles", and each tile is a fully independent screen, and thus each has its own power supply, which runs off a single phase supply. Obviously as the number of tiles goes up, you spread the tiles amongst the phases...
 
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