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Batteries And Mains - Getting It Wrong

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  Batteries And Mains - Getting It Wrong c186282 <c186282@nnada.net> - 2025-09-14 16:47 -0400
    Re: Batteries And Mains - Getting It Wrong "Carlos E.R." <robin_listas@es.invalid> - 2025-09-14 23:10 +0200
      Re: Batteries And Mains - Getting It Wrong c186282 <c186282@nnada.net> - 2025-09-14 17:30 -0400
    Re: Batteries And Mains - Getting It Wrong Marc Haber <mh+usenetspam1118@zugschl.us> - 2025-09-15 09:38 +0200

#74161 — Batteries And Mains - Getting It Wrong

https://www.helsinkitimes.fi/finland/finland-news/domestic/27913-helsinki-tram-disruptions-continue-after-voltage-upgrade-damages-older-fleet.html



Several older trams in Helsinki were damaged over the weekend after
the city’s main tramline voltage was increased. While many units
have now returned to service, City Transport warns passengers to
expect continued changes and possible cancellations during the
coming week.

The voltage increase was carried out between Saturday and Sunday
night to match the power levels used by Helsinki’s newer light
rail lines, including the Kruunusillat route and Line 15. The
network now operates at 750 VDC.

. . .

   Why ... let's just TURN UP THE VOLTAGE  :-)

   I seem to remember a US spacecraft where the
   engineering 'B' Team decided to do the same
   thing ...

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#74167

On 2025-09-14 22:47, c186282 wrote:
> https://www.helsinkitimes.fi/finland/finland-news/domestic/27913- 
> helsinki-tram-disruptions-continue-after-voltage-upgrade-damages-older- 
> fleet.html
> 
> 
> 
> Several older trams in Helsinki were damaged over the weekend after
> the city’s main tramline voltage was increased. While many units
> have now returned to service, City Transport warns passengers to
> expect continued changes and possible cancellations during the
> coming week.
> 
> The voltage increase was carried out between Saturday and Sunday
> night to match the power levels used by Helsinki’s newer light
> rail lines, including the Kruunusillat route and Line 15. The
> network now operates at 750 VDC.
> 
> . . .
> 
>    Why ... let's just TURN UP THE VOLTAGE  :-)

The article says they tested it in advance.

> 
>    I seem to remember a US spacecraft where the
>    engineering 'B' Team decided to do the same
>    thing ...
> 


-- 
Cheers, Carlos.
ES🇪🇸, EU🇪🇺;

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#74171

On 9/14/25 17:10, Carlos E.R. wrote:
> On 2025-09-14 22:47, c186282 wrote:
>> https://www.helsinkitimes.fi/finland/finland-news/domestic/27913- 
>> helsinki-tram-disruptions-continue-after-voltage-upgrade-damages- 
>> older- fleet.html
>>
>>
>>
>> Several older trams in Helsinki were damaged over the weekend after
>> the city’s main tramline voltage was increased. While many units
>> have now returned to service, City Transport warns passengers to
>> expect continued changes and possible cancellations during the
>> coming week.
>>
>> The voltage increase was carried out between Saturday and Sunday
>> night to match the power levels used by Helsinki’s newer light
>> rail lines, including the Kruunusillat route and Line 15. The
>> network now operates at 750 VDC.
>>
>> . . .
>>
>>    Why ... let's just TURN UP THE VOLTAGE  :-)
> 
> The article says they tested it in advance.

   Obviously NOT VERY WELL.

   You don't want to be the one "standing in the
   way of progress" after all  :-)

>>    I seem to remember a US spacecraft where the
>>    engineering 'B' Team decided to do the same
>>    thing ...
>>
> 
> 

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#74213

c186282 <c186282@nnada.net> wrote:
>Several older trams in Helsinki were damaged over the weekend after
>the city’s main tramline voltage was increased. While many units
>have now returned to service, City Transport warns passengers to
>expect continued changes and possible cancellations during the
>coming week.
>
>The voltage increase was carried out between Saturday and Sunday
>night to match the power levels used by Helsinki’s newer light
>rail lines, including the Kruunusillat route and Line 15. The
>network now operates at 750 VDC.

Please note that the voltages in railway catenaries and third rails
have a much higher variance than the voltage we have in wall sockets,
especially in those DC systems that have a voltage of around 1 kV.

Accelerating trains draw obscene currents and the voltage decreases,
modern trains feed back to the catenary / third rail when braking. To
build the trains cheaper, isolation inside the trains is usually
specced for 1 kV even if the train will be used in a 600 V system. In
Germany, many systems have gone from 600 to 750 V in the last decades
to allow better motorized trains to run and to be able to use cheaper,
run of the mill equipment in rectifying stations. It is uncommon to
modify older trains when doing that change, other than blocking the
highest setting in mechanically controlled ("Schaltwerk") motor
control units.

Even in AC systems that usually run at 25 kV (15 in Germany, Austria
and Switzerland) the variance can be higher than two kV depending on
how many trains are accelerating / braking simultaneously.

Nothing unusual happened in Helsinki. And it doesn't have to do with
Linux at all.

Greetings
Marc
-- 
----------------------------------------------------------------------------
Marc Haber         |   " Questions are the         | Mailadresse im Header
Rhein-Neckar, DE   |     Beginning of Wisdom "     | 
Nordisch by Nature | Lt. Worf, TNG "Rightful Heir" | Fon: *49 6224 1600402

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