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-   -   why not 3 phase? (http://www.diyaudio.com/forums/power-supplies/212408-why-not-3-phase.html)

Arty 9th May 2012 09:38 PM

why not 3 phase?
 
This question is bugging me from time to time,
why shouldn't 3 phase powersupply be used for high end audio amplifiers?
Supposedly smoother DC could be achieved, seems quite reasonable.
Might some PA system be using this setup, I'm not realy into those.

Any opinion ?

simon7000 9th May 2012 09:47 PM

3 phase power is rarely available. You want "Y" and most is Delta. So the market would be tiny.

zigzagflux 9th May 2012 09:50 PM

Sure, three phase will provide for a lower ripple power supply, all things being equal. But reasonable it is not. To be done properly, you need either a three phase transformer, 3-single phase transformers, or 2-single phase transformers connected open delta. More iron equals more cost.

Then there is the issue of availability, which for US residents is less than 1% of the population. Utilities normally will not install a three phase service unless kW demand is a minimum value. Chances of getting three phase residential service is almost nil.

Better off with a bigger DC choke than using three phase. Permanently installed high power systems, such as auditoriums, churches, arenas, etc would be fine with it; I'm guessing most of those are 208V.

zigzagflux 9th May 2012 09:52 PM

Nothing wrong with delta; three phase rectifiers only require three legs- they don't use the neutral.

asmith 9th May 2012 10:00 PM

Some amps do.
 
Some of the BIG Crown amps do run on 3 phase. Seems like they made one rated for 10k RMS that had to be run that way.

AndrewT 10th May 2012 01:15 PM

I would expect PA equipment to come with the option to use or be adapted to 3phase supply.

I further suspect that some PA equipment only comes ready wired for a 3phase supply.

KatieandDad 10th May 2012 01:26 PM

MOD always use three phase.

Arty 10th May 2012 03:29 PM

Quote:

Originally Posted by zigzagflux (Post 3018033)
Sure, three phase will provide for a lower ripple power supply, all things being equal. But reasonable it is not. To be done properly, you need either a three phase transformer, 3-single phase transformers, or 2-single phase transformers connected open delta. More iron equals more cost.

Then there is the issue of availability, which for US residents is less than 1% of the population. Utilities normally will not install a three phase service unless kW demand is a minimum value. Chances of getting three phase residential service is almost nil.

Better off with a bigger DC choke than using three phase. Permanently installed high power systems, such as auditoriums, churches, arenas, etc would be fine with it; I'm guessing most of those are 208V.


1% ????
3 phase 16A / phase is the standard here, while i do agree that some residents to not have 3 phase wall connectors. Quite a surprise actualy. I was thinking USA people like dish washing machines and sortha stuff that requires 3 phase usualy.

jitter 10th May 2012 04:31 PM

Ehm, if I'm not mistaken, residental buildings in the USA don't have the 3 phase system but the split phase system (Edison system) to get 110 V or 220 V.

See also this thread.

Speedskater 10th May 2012 04:40 PM

True, very few homes in the US have 3 phase power, only a few in mixed use neighborhoods even have the option.
8000 Volt 3 phase power entries my neighborhood, but only a single phase line goes down each street. Then a single phase transformer steps it down to 240 Volt center tapped.


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