Re: Near miss at Victoria (London)

["MattyQ" <mattyq1009@dingoblue.net.au>]

"Chris Downs" <cvdowns@ozemail.com.au> wrote in message
lS866.170$Ll4.8153@ozemail.com.au">news:lS866.170$Ll4.8153@ozemail.com.au...
> Sydney has no equivalent to Bizzie's 25kV arrangement (such as between
Roma St
> station and the Merivale Bridge or opposite Mayne Car Sheds) where the
> pantograph traverses a lengthy dead section of contact wire rather than
what I
> think of as "air gaps".

These are called "Neutral sections". If my facts are correct, the Neutral
Section is a characteristic of AC Overhead Traction Wiring Equipment (OHTWE)
only.

> Brizzie also has "ski jumps"

"Low speed section insulators".

but only for crossovers
> and sidings.  Other mainline sections (not air gaps or dead sections) have
a
> more intricate version of Sydney's old diamonds that does provide truly
> continuous power.

What you call "air gaps" are referred to in QR as "insulated overlaps"
althought they serve the same purpose. These are always used in preference
to "section insulators" (SI's) on main lines. High speed BICC SI's (what you
call 'diamonds') are used only when there is insufficient room for an
insulated overlap, which requires at least four stanchions to support. An SI
can be placed almost anywhere in the OHTWE.

>
> A question to those in the know:  In many thousands of km travel on
Brizzie's
> sparks I have never seen serious arcing between the pantograph and
overhead as
> I've seen in Sydney on occasions.  But my old man told me such arcing was
> common on some trips he made under 25kV in the UK (loco hauled trains in
all
> cases I think).  Why is this so, overhead quality/age, higher current for
> electric locos or?

QR's 25kV 50Hz AC system is less prone to arcing than Sydney's 1.5kV DC
system for reasons Dave Johnson would be better off explaining. Suffice it
to say QR overhead does indeed arc. Try sitting at Northgate one evening and
watch the Shorncliffe trains depart.


--
Matt Smith
Brisbane, Australia

Email - mattyq1009 at dingoblue dot net dot au

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