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Electric locomotive selectors Rate Topic: -----

#1 User is offline   Serana 

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Posted 24 November 2021 - 07:01 PM

I will work on the addition of electric locomotive selectors soon, so I am opening a discussion in order to collect ideas/remarks.


An electric locomotive may need several selectors. The most common are the following:
- Pantograph selector: a locomotive may raise the pantograph at the front or at the rear or both.
- Voltage selector: a locomotive needs to configure its systems in order to accept the right voltage from the overhead wire.
- Power limiter selector: on some lines, the power available on the overhead wire is limited. The locomotive must be able to limit its power consumption in order to not decrease too much the voltage.

All of these selectors must be scriptable in order to take the particularities of a locomotive into account.

The selectors will give information to the power supply classes in order to trigger the right pantograph and to limit the power of the locomotives.
The power supply classes will also receive information from the TCS in order, for example, to check that the right voltage is selected.

In order to give an idea of what will be available, here's the example of what's available on a TGV Atlantic:

The pantograph selector has 3 positions: normal, rescue, local.
The pantographs that are raised depends on the voltage selected on the voltage selector:
- 1500 V : normal => all pantographs are raised, rescue => all pantographs are raised, local => only the pantograph at the front of the train is raised
- 25000 V : normal => the rear pantograph of each EMU is raised, rescue => the front pantograph of each EMU is raised, local => only the pantograph at the front of the train is raised

The voltage selector has 3 positions:
- 1500 V
- 25000 V conventional line
- 25000 V high speed line

The power limiter has 3 positions: I, II and III.
Depending on the position of this selector, the position of the voltage selector and the number of EMU in the train, the locomotives are power limited to different values.

To answer a question of Chris sent by PM, at first, the power supply class won't be able to know if there is a voltage change on the route. But, with a few signals (for example, a Lower Pantograph signal with C# signal script), the TCS may forbid to raise the pantograph if the chosenvoltage is not the right one after the neutral section.

#2 User is online   Laci1959 

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Posted 24 November 2021 - 11:54 PM

Quote

- Power limiter selector: on some lines, the power available on the overhead wire is limited. The locomotive must be able to limit its power consumption in order to not decrease too much the voltage.


This is called on some railways: Driver, i.e. a specialist.
Sorry.

#3 User is offline   Csantucci 

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Posted 25 November 2021 - 12:22 AM

In the Italian TCS scripts that I have written there is a provision to automatically lower and rise (the latter after driver enable) the correct pantograph depending on the line voltage. The points where to perform the operation are defined by INFO signals.

#4 User is offline   keystoneaholic 

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Posted 25 November 2021 - 03:41 AM

Would it be possible to add additional voltage positions for 3000 volts DC and 750 volts DC? The Eurostar sets run at 25Kv AC in UK, 25Kv AC on high speed lines in France, Belgium and the Netherlands, 3000v DC in Belgium and 1500v DC in the Netherlands. The original Eurostars also ran on 750v DC in the UK before the high speed line from London to Folkestone was opened. I believe that they may have retained this feature for emergency diversions. I'm not too sure about the newer trains. There are conventional EMUs in the UK which run on 750v DC third rail and 25Kv AC.

A number of the modern European freight locos are also multi-current, 1500v and 3000v DC, 15Kv AC (16 2/3 Hz) and 25Kv AC (50 Hz). Some of the most modern also have a 'last mile' (or should that be 'last kilometre') facility of a small diesel engine for slow speed movements in unelectrified tracks. I realise that this is all added complication, but if it is possible to build in 'hooks' to allow for developing these features even if they are not implemented immediately it could save a lot of rewriting code in the future.

I'd offer to help, but my coding skills were in COBOL, with a bit of BASIC thrown in. I tried to pick up 'C' but it went completely over my head, it felt like the lecturer lived on a different planet.

#5 User is offline   darwins 

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Posted 25 November 2021 - 05:49 AM

Related to the above - third rail. Not all electric trains have pantographs. It is quite annoying having to raise the pantograph of a train that uses a third rail system.

The old Eurostar sets as mentioned could use 750 v dc third rail as well as the three different overhead line voltages.

There were a small number of British locos that could take 750 v dc either from third rail or from an overhead line when in yards.

Also the French CC 6500 which originally used third rail rather than overhead on the Maurienne section.

#6 User is offline   Weter 

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Posted 25 November 2021 - 02:14 PM

Old-fashioned locomotives often had selectors for choosing motor groups arrangement (serial, mixed, parallel) or excitation field weakening.
Some functions could be combined with throttle handle, or we're automatically adjusted.

#7 User is online   Laci1959 

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Posted 25 November 2021 - 11:52 PM

Quote

Old-fashioned locomotives often had selectors for choosing motor groups arrangement (serial, mixed, parallel) or excitation field weakening.


Hello

That's right. Parallel switching was used either to start or permanently in freight locomotives.
In the MÁV V43 locomotives, the gear switch ( throttle handle ) gave the speed and the shunt switch ( excitation field ) gave the force. It was available from 9th grade and had 4 positions.

Yours sincerely, Laci 1959

#8 User is online   Laci1959 

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Posted 26 November 2021 - 12:33 AM

Quote

- 25000 V conventional line
- 25000 V high speed line


What is the difference in the design of the overhead line apart from fixing it?

#9 User is offline   darwins 

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Posted 26 November 2021 - 12:57 AM

View PostLaci1959, on 26 November 2021 - 12:33 AM, said:

What is the difference in the design of the overhead line apart from fixing it?


The difference is the amount of current that an individual loco is allowed to draw. The result is that higher power is available on high speed lines.


#10 User is online   Laci1959 

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Posted 26 November 2021 - 01:08 AM

So a larger cross-section work line and a support line. Higher power, possibly more densely distributed electrical substations.
I see. But these are outside the locomotive, independent of it.
I mean, the power consumption of the high-speed locomotive, the electronics, the winding of the motor, the values of the circuit fuses are scaled to the speed. Etc. But why switch to these when driving at a normal speed?
Or is it just replacing a pantograph and Google Translate having fun with me?

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