On Wed, 27 Nov 2013 20:18:17 -0600, Nightcrawler®
wrote:


wrote in message ...
On Tue, 26 Nov 2013 22:35:46 -0600, Nightcrawler®
wrote:


wrote in message news
I believe most generators in the use are Delta, where loads, as you
state, are Wye. Transimisson is Delta as is most distribution, IIRC.

Most, that I have installed, are Wye. Onsite protection of these units
is simpler and more cost effective. 3+ units going straight onto grid
as Wye (stepped up, of course) or a Wye-Delta step-up. However, most
long range delivery is done via a pure Delta (no neutral) system.

You install power company generators? Why would protection be
simpler?

I used to install power-plant generators, yes. Not utility
generators. These private plants fed the grid and were under
the ultimate control of the utility, meaning that the utility
could kick them off-line, at will. Most of the plants were
not stand-alone. If the grid went down, they went down. The
gas-turbine plants were stand-alone, and some city service
generation facilities were, also.

That's an entirely different kettle. Of course they're Wye connected
because that's what the customer sees. the POWER COMPANY'S generators
*are* delta connected, as is the transmission system.

Per generator:

A Wye system only has the standard voltage/amperage/frequency/
ground-fault protective systems. Each phase has one bus, two
detection transformers (CT and PT), and the neutral is grounded
through a current transformer. The neutral does not go out
of the plant. The ground fault and generator detection trans-
formers are installed on the generator side of the 52G breaker.

At the customer end, OK, but that has nothing to do with the power
company.

The utility only has one set of detection devices in the plant,
right after the service entry switch. This set-up provides the
best user safety for power generation.

Delta systems are set up primarily the same way with the exception
that they usually do not have a grounded leg, hence, no reference
to ground. To get a reference to ground requires a complicated
and costly system that is separately derived from the direct gener-
ation process.

Huh? Delta has no neutral.

These things take up a lot of space. There is no way
to have these units inside the control room as with the Wye set-
up. Each phase of each generator will have a transformer 1/3 the
size of a standard pole pig. This is quite a footprint. My
memory of the exact set-up is rather vague, but I do recall
a set-up that only sensed the outgoing feed to the step up
transformer. That took up a roughly 8' dia. area of ground.
I might try to pull up a picture via Google maps.

"Distribution panel"? Are we talking about the same thing?

In industrial/commercial building(s)/complex(s), the service is
brought into a distribution panel. This service is 1200 amps
and up. The distribution panel feeds other distribution panels
directly (building), via meters (complex--separate business'), or
a combination of the two. The primary distribution panel uses
large form factor circuit breakers that have adjustable magnetic
trip settings and are sized, amperage wise, for the load anticipated,
either via load calc, or other means. Say, a 400 amp feed to what
will be a production facility that uses large machinery and other
devices that draw heavy current loads. A 200 amp feed to another
section that does not have a purpose at the time of installation
and so on until all of the spaces in the dist. panel are used up,
or only the immediate (known) service sourcing is to be powered.
Why waste the money before the use for the space is known?

You're talking about an *entirely* different issue and irrelevant to
the discussion.

(I have to step out for a bit, so I will not be able to finish
at this time)