Re: Near miss at Victoria (London)

[jjjim <jjjim@bigpond.com>]

HEeh yeah Thats the thing with DC arcs i supose  they just dont stop ;)  i
forgot about the longer feeds with Hi tention supplies ,  God knows how many
trains would be running off it at any given time.  I know for a fact the
cleveland line here in brissy runs one power source for  about 20Km before
switching to the lyndum substation (train Rolls un powered for about 50m  till
breaker comes back on)

Dont know if thats a good example tho of maximum  distance for the hi tention
supply *shrug*

JJJim

Aus Visitor wrote:

> David Johnson wrote in message <3A566E88.58ED4F98@ozemail.com.au>...
> >jjjim wrote:
> >
> SNI,  But u can image
> >> the Arc  with to trains at full power,  on a 22Kv line.   So id say  they
> >> are only used as 'definate' isolation of power,  rather than cutting
> power
> >> while online
> >
> >I would suggest a breaker or knife switch opening 25kVAC at 50 Amps would
> have
> >a much smaller arc than opening 1500VDC at 1000 Amps.
> >
> >--
> >David Johnson
>
> Yes it does - though the current is often over 50 amps on a 25KV line - it
> feeds a longer section hence more trains drawing current.  Also the 25 KV is
> AC so the ARC is self extinguishing.  For the DC breakers they have
> compressed air to blow the ARC out!!  Oh its also noisy when they blow as
> well!!
>
> AV