You'd wonder why such colossal current spikes are required on start
up...and whether there's something simple to ameliorate it.
Mark Skinner
On Mon, 15 Aug 2022, 11:54 am TP, historyworks@...> wrote:
> The problem, as with many comparisons, is the lack of matching information
> about the things you're comparing. You can get certain stats about one and
> an overlapping set of other stats about the other, but not a common set for
> both. I would like to know what would be the current draw on acceleration
> of a Skoda 15T or a set of Tatra T3s. The only clue I ever got is when I
> asked once whether the fast acceleration of Prague trams resulted in higher
> operating costs and was told that the difference was so tiny they stopped
> measuring it years ago, so that suggests it's not a big issue for them and
> they often have multiple trams accelerating together with their stops
> holding two trams. Yet it's an issue in Melbourne?
>
> Tony P
>
> On Monday, 15 August 2022 at 10:32:05 UTC+10 Mal Rowe wrote:
>
>> On 15/08/2022 09:53,peterm...@... wrote:
>> > 1500A on a 600V overhead, is not good in terms of voltage drop. Ive
>> > not been to Melbourne for a while, is it still a single contact wire,
>> > or are there dual contact wires and additional feeder wires like
>> > railway approach to reduce voltage drop?
>> >
>> There are multiple feeder cables throughout the system and no places
>> that I am aware of where there is noticable voltage drop.
>>
>> I was told at a safety briefing by Yarra that the trip current from a
>> substation is usually set at 2500A - meaning that up to 5000A is
>> available in a typical section fed from both ends.
>>
>> There are no double contact wires that I am aware of, but there are
>> places where an extra set of contact wires is hung on the overhead as
>> feeders. You can see them in my pic at: https://tdu.to/i/52233
>>
>> The light rail lines to St Kilda and Port Melbourne still have the
>> heavier contact wire and catenary from railway days.
>>
>> See my pic at: https://tdu.to/i/39803
>>
>> Mal Rowe - who once knew a bit about Elec Eng
>>
>>
>>
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