[Milsurplus] AC Power on Ships

[Richard Brunner]

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