I just calculated the peak voltage for 25,000 Vac RMS (root mean square), which is the AC voltage measured for rating appliances etc.
It is 35,350 V. Total voltage difference peak to peak is 70,700 V. That’s a lot of volts to be pulsing through a confined space 50 times a second, inducing current into everything it touches, including human bodies.
Tony
> On 5 Dec 2023, at 11:37, Tony Galloway arg@...> wrote:
>
> The other problem with HVAC, particularly underground, which is rarely discussed, is the corona of pulsating EMF it induces, which, unsurprisingly, is unhealthy to be immersed in for a long period of time.
>
> Like X-rays, microwaves and radio waves, this non-ionising radiation has negative health effects on the human body, and unlike mainline electrification where the catenary can be strung high enough to minimise the effect, the overhead here will be in much closer proximity to people and the EMF effect stronger.
>
> With Brisbane, and to a lesser amount Perth, the larger networks give more scope for phase balancing with less of the necessary complexity Matthew describes, where a single phase change sub can cover a much larger area than even the longest single metro route. There’s always three phases with their power factors to keep in balance, irrespective of the line length, so the claimed advantage of HVAC - less and cheaper (non-rectifying) substations, is cancelled by the need for phase balancing the supply.
>
> Anyway, my prediction is by the time this delusion driven fantasyland opens, the big theme park of western Sydney will largely be uninhabitable with a permanent 50 degree plus heat dome over it for most of the year, with an unusable airport due to heat rarified air.
>
> Tony
>
>> On 5 Dec 2023, at 11:03, TP historyworks@... mailto:[email protected]> wrote:
>>
>> I don't know where this idea of short Sydney metro lines comes from. They're all longer, or going to be longer than some AC powered Perth (and probably Brisbane) lines. Metro West is starting off at 24 km for Stage One, but will be something over 70 km when it's completed to it's ultimate destinations, Bradfield and Little Bay. Western Sydney Metro is starting off at 23 km, but will be about 60 km when it's completed to Macarthur and Schofields.
>>
>> Another misapprehension is the assumption that WSA needs to be connected to Sydney Airport (via Leppington line). Such a connection will be available, but it's a tiny component of the reason for the project, which is to serve western Sydney. The most important rail links for WSA at the outset will be to western, NW, SW Sydney and to Parramatta. Kingsford Smith will continue to operate forever as the airport to service eastern Sydney. A lot of non Sydney people don't comprehend that Sydney is a highly decentred city, with its population and geographical centre near Parramatta. The population is balanced across western and eastern Sydney, presently about 2.5 million in each. WSA is the airport for western Sydney, but will likely achieve eventual dominance over Kingsford Smith because of its greater capacity and efficiency and being a 24 hour airport.
>>
>> There's also going to be an extension of the Sydney freight rail network to the airport industrial areas.
>>
>> Tony P
>>
>> On Tuesday, 5 December 2023 at 10:38:29 UTC+11 Matthew Geier wrote:
>> I can see I'm not the only person who thinks making short 'metro' lines
>> run on 25kv AC is not sensible.
>>
>>
>> And for Metro West, the will have to make the tunnels slightly larger
>> (smaller tunnels being cheaper was one of the justifications for the NW
>> Metro!) to ensure adequate clearances. And it will also have the same
>> phase balancing problem as the airport line being a relatively short
>> line by railway standards.
>>
>> So it too will need more complex and expensive 'frequency converter'
>> substations so the entire line can run as single phase and not need
>> phase breaks.
>>
>> Maybe there is a good engineering justification for making short metro
>> lines 25kv AC, but I can't see what it would be from the outside. All I
>> can see is increased complexity and train weight.
>>
>>
>>
>>
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