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Re: DC Supply



 
 > Original Poster: Mark Finnis <mefinnis-at-medicine.adelaide.edu.au>
 
 
 > Have genuine 3-phase to my house to supply a large air-conditioner.  Could
Greg:
 Wow, you're all set!  Just hang a NST on each phase. 
 Tapping the A/C power seems much easier and more fun 
 than trying to build a phase shifter.


Hi all,
Mos european countries have access to 380 (400) volt 3 phase mains because the
homes are fed with 3 phases to distribute the load. A 3 phase psu will only
work if you go to DC. I think Mark wanted to use an AC supply, which would
require a phase angle correction ("shifter" if you like) If you were to
connect 3 xformers (from Ph1 Ph2 Ph3 to N) and simply series these it wouldnīt
do any good, because you have a phase angle difference between each phase of
120°, so you wouldnīt be getting 3x1 NSTīs output voltage (It would get you
NST1*phase angle plus NST2*phase angle plus NST3*phase angle. You couldnīt
parallel them either for the same reason. So for AC this is no go. If you want
DC then itīs no problem just rectify each xformer and connect them or run all
three (star config) into a 3 phase rectifier. These means the cold end of all
three xformers are connected together (N) and each hot end is connected to the
rectifier (3 x L)
You could, however run two transformers in series (primary) and connect them
across two phases (i.e. 380V) to reduce the current strain on your mains
(fuses).

Coiler greets from germany,
Reinhard