[Milsurplus] AC Power on Ships

[Richard Brunner]

I think you're right about the nearby MG set.  The LST-325 has an
additional MG set too, for modern convenience.  However when steaming I
think they are pure DC.  Upon further reflection there must have been
some auxiliary ac power in the big boats because most navy receivers had
ac supplies, but the big transmitters were all motor-generator, usually
DC.

Richard, AA1P


On Sun, 2010-10-24 at 17:38 -0700, J. Forster wrote:
> The radio spaces (at least) on the BB-59 (Massachusetts) have floating AC.
> I think there may be a nearby MG set.
> 
> The question came up in connection with a blown EMI filter a C-L-C Pi
> network.
> 
> Thank you,
> 
> -John
> 
> ==============
> 
> 
> 
> > First, all the WWII ships I have seen were DC, nominally 110-120
> > volts.
> >
> > There is nothing wrong with an ungrounded ac system.  It has the
> > advantage that you can continue to operate with the first ground fault,
> > and the second will trip it off.  Also ground fault current (for the
> > first fault) is limited by system capacitance to ground, and is small.
> > For comparison, fault current on a grounded system is high, and any
> > fault will trip it off.  Drop your screwdriver on the grounded system
> > and you get a big flash and burn, with the ungrounded system it's merely
> > a little spark.
> >
> > Richard, AA1P
> >
> > On Sun, 2010-10-24 at 15:18 -0700, J. Forster wrote:
> >> Hi,
> >>
> >> I was just asked about the AC line on WW II era ships. It appears there
> >> is
> >> no neutral and the 115V 60 Hz just floats with each line 60-80 V AC
> >> above
> >> structure.
> >>
> >> Is this correct and common or is there a fault?
> >>
> >> And, more importantly why would they do it this way?
> >>
> >> Best,
> >>
> >> -John
> >
> >
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