On Fri, 26 Dec 2003 14:09:27 GMT, Larry W4CSC wrote:

On 26 Dec 2003 01:19:31 -0800, (Rob) wrote:

Hi,

Both Charles Wing and Nigel Calder allude to connecting the neutral
and ground wire of AC generators at the generator. Both authors also
show alternator generators with a centre tap at 0v and the other two
conductors at +60/120v and -60/120v (giving 120 and 240v
respectively). The 0v centre tap I think is connected to ground, but
is one of the conductor wires really connected to the ground??? Both
authors have produced diagrams with no ground/conductor connection
shown. It seems a little odd - grateful for clarification.

TVMIA

120/240V gensets are, at least in the USA, set up like USA's
antiquated, unstandard AC power system, just like Tesla created it.

120V-------Neutral---------120V

The two 120V are out of phase (180 degrees), so if you connect from
120 to 120 you get 240 VAC to power big items. Our National Electric
Code requires the Neutral (center tap of the transformer secondary out
on the street) be a separate wire to carry the current from ground,
even though they are both connected together at the pole. There is no
60-0-60 power, here.

However, on ships, to reduce the voltage to ground reducing shock
hazards on 120V power systems, there IS a 60-0-60 system with a
center-tap-grounded power system. I used to serve on old Navy ships
that had this system. Not sure if they still use it on new ships,
now.

So, any 120/240 genset targeted at the US/Canadian market will have a
4-wire system, two 120V phases 180 degrees out of phase, a neutral
wire to carry the current to the center-tapped windings and a separate
ground which is the case of the genset and should be hooked to the
center tap of the genset's windings at the genset ONLY.

Hope this helps

Larry W4CSC

NNNN

Larry,

Being totally unfamiliar with naval systems, the question Rob asked still
remains: Is the neutral (in a 60 - 0 - 60 system) connected to one of the
60 volt legs? Is it still coded white? I'm assuming that ground is always
connected to frame or earth ground in any system.
--

Larry
email is rapp at lmr dot com