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Ph-ph-phases!
7 years ago
General
Another thing I learned at AX this year -- or rather, finally noticed -- had to do with the electrical system. I've posted pictures before of the 150kVa transformer carts that are set up backstage, and that these supply five pigtail connections (three phases plus neutral and ground) that are then distributed via various states of spaghetti throughout the backstage area. There are blocks that distribute all three phases (plus neutral and ground) down one five-conductor cable with a five-connection twist-lock plug at the end. You can even see over each socket there are status lights for each phase above their color (black/red/blue).
There was another variety of distribution box that took the five separate pigtails and broke it out into 240- and 120-volt plugs. The inside of the box was circuit breakers, with four 240-volt twist-lock sockets opposite the pigtails and the other two sides were all 120-volt 20-amp Edison plugs. And I noticed that the plugs were colored black and red and blue. That is, each plug was on a different electrical phase, which made for a greater current capacity than if they were all run from a single phase.
That would have been all, except later I was standing in line to see the premiere of "Dragon Pilot", sweating it out with all the other poor unfortunate souls under an awning. I looked up and around the rim of the awning was an electrical cable with a plug-box every 10 feet or so. And as I looked, I realized that on each box, the plugs were a different color. Black... red... blue... it was a five-conductor cable carrying all three phases and once again, giving three times the potential capacity of a single-phase cable.
Of course, I say extra capacity, but you still have to use your brain. If you plug all your illumination into only red plugs, then of course you're going to load down that one phase and might trip a breaker. But if you spread all the lights out among the different phases and balance it a bit, you could push a lot of watts!
Even backstage, there were cute little boxes that could pass-through a 5-conductor twist-lock and had three plugs (black/red/blue!) so you could locate an easy 120-volt power tap wherever you needed it. It was a small detail, but one I thought was pretty cool to notice.
There was another variety of distribution box that took the five separate pigtails and broke it out into 240- and 120-volt plugs. The inside of the box was circuit breakers, with four 240-volt twist-lock sockets opposite the pigtails and the other two sides were all 120-volt 20-amp Edison plugs. And I noticed that the plugs were colored black and red and blue. That is, each plug was on a different electrical phase, which made for a greater current capacity than if they were all run from a single phase.
That would have been all, except later I was standing in line to see the premiere of "Dragon Pilot", sweating it out with all the other poor unfortunate souls under an awning. I looked up and around the rim of the awning was an electrical cable with a plug-box every 10 feet or so. And as I looked, I realized that on each box, the plugs were a different color. Black... red... blue... it was a five-conductor cable carrying all three phases and once again, giving three times the potential capacity of a single-phase cable.
Of course, I say extra capacity, but you still have to use your brain. If you plug all your illumination into only red plugs, then of course you're going to load down that one phase and might trip a breaker. But if you spread all the lights out among the different phases and balance it a bit, you could push a lot of watts!
Even backstage, there were cute little boxes that could pass-through a 5-conductor twist-lock and had three plugs (black/red/blue!) so you could locate an easy 120-volt power tap wherever you needed it. It was a small detail, but one I thought was pretty cool to notice.
Warphammer
~warphammer
Yup. Three phase power strips do similar things. :)
Kerosel
~kerosel
OP
I'm going to guess that's something one would see in a high-powered data center? It certainly would be handy to have in a rack so that only every third server is sharing a power connection instead of all of them trying to drink from the same well.
Warphammer
~warphammer
Yes. Generally at fancier data center you'll get two independent three phase feeds into each rack, if you ask for it. Just increases density. You oft run out of cooling capacity before space or power in that kind of setup.
