[BC] AC Voltage Drop

[Milton R. Holladay Jr.]

IIRC, there is a wye secondary and a delta secondary which wind up being 60
degrees different in phase such that, combined,  there are 12 pulses per
cycle resulting from the 6 sets of rectifiers. The ripple is so low that no
choke is required on the input of the fillter capacitor bank.
I've heard them called 6 phase and 12 phase. Ftitz Bauer used it on his
FB-5J and Collins adopted it also, as it worked especially well on AM xmtrs
due to the low source impedance/very good regulation  of the non-choke input
filter power supply accommodating the pulsating load of an AM xmtr.
Perhaps Richard can probide more tidbits................
M
----- Original Message -----
From: "Dave Dunsmoor" <mrfixit at min.midco.net>

> > Since 12-pulse (or 12-phase) transformers were expensive, ...
>
>     Richard (or anyone else who would care to reply), I've asked this
> question before, and now am going to have to admit to some forgetfulness:
> how exactly does this 12-phase business work? Where do you get the
> nomenclature "12 pulse" (or phase) from a 3 phase incoming main AC, and
how
> does combining 2 secondaries constitute something that can be considered
to
> be 12 phases?
>
>     If I had 3-phase available in my shop, I'd see if I could rig
something
> up to scope it out to follow it. But, not having that available, I think
> I'll have to rely on answers here, and going back to the drawing board
with
> a math review.
>
> Dave Dunsmoor