Re: [IRCA] OT: Electricity as a form of dementia

[Charles A Taylor <MWDXer@xxxxxxx>]

At 10:49 PM 4/22/2007 -0400, you wrote:
>CT -
>
>Why voltage choices?

The phase-phase voltage amongst the IOUs (commercial)
utilities is 12 kV in CA. The most widely used voltage in
North America is 12.47 kV, which is 7.200 x 1.73. So
your pole transformer is 7,200Y Gnd/240.

7,200 is 3 X 2,400 V. 2400=20 X 120. 120=one of the
old Edisonian lamp voltages.

2400
4160
7200
12470 "12.5 kV"
24940 "25 kV"

But here's the progression of most common sub-
transmission & transmission voltages in NA:

34.5 kV
46
69
115
138
161
230
345
500 (East Coast Grid voltage)
765 (American Power System, only)

Except for the last two, they are based on the
old Edisonian lamp voltage of 115 V.

12 kV in CA is 6.9 kV x 1.73 (really 11.937 kV).

But there are "legacy" voltages that are no
longer built upon new:

6.6 kV
44   (Duke Energy subtransmission [and now distribution])
33   (old Carolina Power & Light Co.)
66   (Southern California Edison)
110  (now replaced by 115)
132  (Southern California Edison)
220  (now replaced by 230)
These are based on the old Edisonian lamp voltage of 110 V.

Edison's lamp company built lamps and segregated them into
three voltage classes according to their nearest most
efficient terminal voltages: 110, 115 and 120 V.

Then he assigned generator voltages to his companies to
accommodate these voltages. Therefrom came the above
voltages. A very little known fact. 95% of electricians
& engineers don't know that.

Subtransmission is that part of the bulk power system
whose purpose is to energize distribution substations.

But with the push for higher voltages for greater
efficiency, many old transmission voltages became sub-
transmission voltages, and lower subtransmission
voltages became distribution.

34.5 kV is a common distribution voltage out here.
Old 34.5-kV delta subtransmission systems were re-
configured to Y, neutrals run, and became distribution.

The highest distribution voltage I've seen personally
is 46 kV, belonging to Alleghany Power Co. Also still
used to energize distribution substations. Duke's
counterpart is 44 kV, used in same circumstances.

Transmission systems look to be delta, but are in
fact grounded Y systems. The neutral isn't there in
function (doesn't need to be) but in fact, as the
overhead ground conductors (lightning protection)
run continuous from transmission substation to
substation. You look at a transmission transformer,
you see three conductors in and out, but the neutral
is there...only it's connected to the tank and ground.

And the big step-down and step-up transformers are
almost all autotransformers. A 230/115-kV stepdown
is centertapped.

Okinawa Power Corp. used 13.2, 66, 132, and 264 kV

But Japan and Korea now use 120-V based systems.

Japan uses 1,000 kV for a grid voltage!

Europe, Middle East and Africa use 11, 22 and 33
distribution voltages. Delta.

Now you know just exactly what your little heart
wanted to know.

Sparky


   Charles A Taylor, WD4INP
  Greenville, North Carolina 
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