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VK4LU > INFO 23.07.02 03:34l 36 Lines 2098 Bytes #999 (0) @ WW
BID : 593-VK4LU
Read: DB0FHN GUEST
Subj: RE AC/DC TRANSMISSION OF POWER
Path: DB0FHN<DB0ZWI<DB0HDF<DB0HOT<DB0ERF<DB0FBB<DB0GOS<ON0AR<ON0AR<ZL2BAU<
VK4TUB
Sent: 020723/0043Z @:VK4TUB.#NQ.QLD.AUS.OC #:26709 [WormHoleBBS] FBB7.00i
From: VK4LU@VK4TUB.#NQ.QLD.AUS.OC
To : INFO@WW
[¯¯¯ TST HOST 1.43c, UTC diff:-10, Local time: Tue Jul 23 09:55:34 2002 ®®®]
Hi all out there in Packetland. Seems the discussion on DC transmission
and thyristors has died down. Thought I would add another Two pennorth.
Here in Queensland most of our power generation is done in the South/East
corner of the State. This is over a 1000Km from some of us in the North.
Now a quarter wavelength at 50hz is 1500Km as a ballpark figure. Now as
anyone knows, trying to feed a reactive load with quarter wavelength line is
asking for trouble. In Queesland this problem is addressed by having a
thyristor controlled bank of capacitors at Nebo. This system switches very
fast and corrects the S.W.R. on the line. At the northern end a small
Hydro station at Kareeya is normally run over-excited as a rotary capacitor
to furthur address the problem. I assume most reading this would be
MilliAmp types. If not for S.W.R. read Power factor.
A further use of Thyristors is in the Coal transport in central Qld. The
Electric Locos are supplied with 22KV 50Hz single phase power from overhead
lines. The overhead line single phase supply is derived from a 3 phase
system which runs parallel. One phase is supplied to the catenary while
the other two phases are split using capacitors and thyristors and taken to
Earth. The thyristors used are about the size of a cooking pot... They go
bang in a big way in the present 115KV grid when they fail. Which reminds
me. At the moment they need to upgrade to a 250KV grid. Bit difficult
since people have built up right to the edge of the 115KV corridor. 250KV
needs a wider swath of country. Old case of penny Wise, Pound foolish.
Suppose the loose nuts at the wheel will take the cheap way out and buy up
an easment for 250KV. Let our kids worry about the time comes when we need
to go to 500Kv and 1MV.
73's from RAY VK4LU@VK4TUB.#NQ.QLD.AUS.OC rayvk4lu@yahoo.com.au
TSTHOST v1.43c
MEMBER W.I.A. & T.A.R.C.
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