>> Yes the overhead [for the new Sydney Australia LRT line] does appear
>> to be for normal pantograph operation,
>> > however what is different is that; double contact wire has been hung. I
>> > am not sure of the reasoning for this maybe someone else can provide the
>> > answer, it may have something to do with better pick up for the 750V dc
>> > taction current. I have noted new overseas Light Rail systems also using
>> > double contact wire as well.
>> I would be interested to know why this is done, too. The new tramway
>> system at Sheffield UK uses this kind of double-contact wire, as do some
>> of the new French tramway systems, ie Rouen. The contact wire used seems
>> thicker than the single wire used on most tramway systems. Some existing
>> tramways seem to be converting to it -- ie I am looking at a photo of a
>> tram on route 1 in Cologne in Germany and the overhead is of the double
>> kind.
>two smaller diameter wires side by side could provide a larger contact
>patch
>with the moving conductor than one single wire. I havent really had a
>good look at the overheads to really know what I am talking about tho.
Yep.
To my knowledge developed by GE in the US, ca 1915, in the run up to
the 3000vdc electrification of portions of the Chicago, Milwaukee,
St Paul & Pacific. Extensive testing indicated improved (low sparking)
high amp pickup. I had always ASSumed that iot was not needed for
lrv/trolley/tram work, due to lower current/power requirements. It
seems there is a place for it. Also allows (dunno if so implemented,
on the modern systems) locating the droppers for each contact wire
at the mid point of the adjacent, so improving vertical flexibility.
thanks
dave pierson |the facts, as accurately as i can manage,
Digital Equipment Corporation |the opinions, my own.
334 South St |
Shrewbury, Mass USA pierson@gone.enet.dec.com
"He has read everything, and, to his credit, written nothing." A J Raffles