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Old March 22nd, 2016, 11:38 PM   #3201
Coccodrillo
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At the beginning of XX century there weren't many options. One was DC electrification, the other low frequency AC.

At that time AC monophase motors produced too many sparks on the collector (a part of electric motors) if working on high frequency, and so needed a low frequency to work. That's why they choose 16 2/3 Hz, which is exactly 1/3 of 50 Hz, the frequency of the main network (in Europe, a great part of the world uses 60 Hz).

Converting frequency is not easy, so the first way was simply putting a 50 Hz motor mechanically coupled to a generator with 3 times less poles, which gave 50 / 3 = 16,666666...Hz (+/- a tolerance).

While this anormal frequency required a separate supply network, it had other advantages over DC. Some countries though the other way round (like Italy which choose 3 kV DC), deciding that the advantages of DC were higher than its disadvantages. While in the 1920s both systems where roughly on the same level, today it is clear that AC systems are better (even at 16,7 Hz).

A wide range of frequencies have been tried, both on railway traction and industrial networks, but today the only frequencies used on large networks are 50 and 60 Hz for much of the world's main electrical network, 16,7 Hz for railways mainly in German-speaking and Scandinavian countries, and 25 Hz on the Northeast Corridor in the USA.

Note that 16 2/3 and 16,7 Hz are not the same thing, the explanation can certainly be found also in English (here in Italian: http://www.sguggiari.ch/3_16_2_3_Hz_o_16_7_Hz.php).

From a performance point of view, 25 kV 50 Hz, 25 kV 60 Hz and 15 kV 16,7 Hz (and the 12 kV 25 Hz on the Northeast Corridor) are roughly equal, so there is no need to covert 16,7 Hz network to 50 Hz, because there is already a fully functional 16,7 Hz production and distribution infrastructure. That's different for new rail electrifications, which use either 50 or 60 Hz depending of the main industrial network of the region.

Maybe it would be practical to standardize the electric network of the Northeast Corridor (and its branches), as it is relatively short and electrified with three different currents (25 kV 60 Hz, 12.5 kV 60 Hz, 12 kV 25 Hz).
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Old March 23rd, 2016, 06:11 AM   #3202
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Quote:
Originally Posted by Coccodrillo View Post
At the beginning of XX century there weren't many options. One was DC electrification, the other low frequency AC.

At that time AC monophase motors produced too many sparks on the collector (a part of electric motors) if working on high frequency, and so needed a low frequency to work. That's why they choose 16 2/3 Hz, which is exactly 1/3 of 50 Hz, the frequency of the main network (in Europe, a great part of the world uses 60 Hz).

Converting frequency is not easy, so the first way was simply putting a 50 Hz motor mechanically coupled to a generator with 3 times less poles, which gave 50 / 3 = 16,666666...Hz (+/- a tolerance).

While this anormal frequency required a separate supply network, it had other advantages over DC. Some countries though the other way round (like Italy which choose 3 kV DC), deciding that the advantages of DC were higher than its disadvantages. While in the 1920s both systems where roughly on the same level, today it is clear that AC systems are better (even at 16,7 Hz).

A wide range of frequencies have been tried, both on railway traction and industrial networks, but today the only frequencies used on large networks are 50 and 60 Hz for much of the world's main electrical network, 16,7 Hz for railways mainly in German-speaking and Scandinavian countries, and 25 Hz on the Northeast Corridor in the USA.

Note that 16 2/3 and 16,7 Hz are not the same thing, the explanation can certainly be found also in English (here in Italian: http://www.sguggiari.ch/3_16_2_3_Hz_o_16_7_Hz.php).

From a performance point of view, 25 kV 50 Hz, 25 kV 60 Hz and 15 kV 16,7 Hz (and the 12 kV 25 Hz on the Northeast Corridor) are roughly equal, so there is no need to covert 16,7 Hz network to 50 Hz, because there is already a fully functional 16,7 Hz production and distribution infrastructure. That's different for new rail electrifications, which use either 50 or 60 Hz depending of the main industrial network of the region.

Maybe it would be practical to standardize the electric network of the Northeast Corridor (and its branches), as it is relatively short and electrified with three different currents (25 kV 60 Hz, 12.5 kV 60 Hz, 12 kV 25 Hz).
I'll note that the electrical network south of New York is obsolete for a secondary reason -- the catenary is variable-tension. When it was first installed in the 1930s there was no clear superiority (and few trains went faster than 100 mph anyhow); nowadays, constant-tension catenary is needed if trains are ever to go faster than 110 mph south of New York.

Converting the NEC to a single catenary standard (and applying it to the rest of the country) is undoubtedly a massive benefit, one helped along by the ex-PRR electrical network being undermaintained and obsolete in its physical plant; a major issue that Europe's multiple nets of incompatible legacy networks incurs is the need to install multiple sets of power collection equipment in international trains, thereby making them heavier. But of course the European railroad power nets are also much better maintained.
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Old March 23rd, 2016, 09:38 AM   #3203
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Quote:
Originally Posted by Coccodrillo View Post
From a performance point of view, 25 kV 50 Hz, 25 kV 60 Hz and 15 kV 16,7 Hz (and the 12 kV 25 Hz on the Northeast Corridor) are roughly equal, so there is no need to covert 16,7 Hz network to 50 Hz, because there is already a fully functional 16,7 Hz production and distribution infrastructure. That's different for new rail electrifications, which use either 50 or 60 Hz depending of the main industrial network of the region.
There is one 'small' point though. Power frequency is one of the main parameters determining transformer size. The higher the frequency the smaller the transformer can be. There is table on page 3 of this article. It roughly states that a 16,7Hz transformer is about 3% less efficient (that's a lot of extra heat!) and also about twice as heavy as a 50 Hz transformer. ABBs solution is interesting though: rectify the high voltage, invert it to a high frequency of 5 kHz to 10 kHz, then send it through a transformer and then rectify again for the inverters driving the motors. Despite all the extra components efficiency is said to be over 99%, irregardless of the power frequency.
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Old March 23rd, 2016, 11:12 AM   #3204
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You don't need to replace traction motors.
Unfortunately you do, because of insulation. If used under 3 kV, motors have
to be insulated for 3 kV, including the wires in the motor coils. The fact that they are used two in series doesn't change anything. Not doing it would be a major security hazard. So yes you might keep them, but then you need to
rewire them completely, which would probably be more expensive than
purchasing anew.

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and the majority of the power electronics don't need to be changed either
3 cases to consider :
- old equipment still using resistor sets : to be completely changed because of insulation reasons, like said above. But I suppose you don't have so much of
that anymore...

- DC serial motors with choppers : that I suppose you still have a lot of. Has to be completely renew because the thyristor chains have now to withstand a voltage of 3 kV rather than 1500 (but only half the current, so you need more in series and less in parallel)

3 phases motors : there you have more chances to be able to re-use most of the components, indeed.

Quote:
Originally Posted by M-NL View Post
Most modern trains, regardless AC or DC, except for some 1.5 kV DCs, are essentially running on about 3 kV DC. The AC models have an additional transformer and rectifier to produce that DC voltage.
For that I would like to know your source because as far as I know,
the "internal power bus" of a multivoltage train is usually 1500V, not 3000.
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Old March 23rd, 2016, 11:14 AM   #3205
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Quote:
Originally Posted by M-NL View Post
ABBs solution is interesting though: rectify the high voltage, invert it to a high frequency of 5 kHz to 10 kHz, then send it through a transformer and then rectify again for the inverters driving the motors. Despite all the extra components efficiency is said to be over 99%, irregardless of the power frequency.
This is basically the same way as all those universal wall warts that charge our mobile phones, and tons of other devices work, but scaled up. A nice thing of this ABB system is that this in fact gives you an universal power supply for locomotives. So your train can run on any DC or AC voltage...
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Old March 23rd, 2016, 11:16 AM   #3206
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Quote:
Originally Posted by Coccodrillo View Post
Converting frequency is not easy, so the first way was simply putting a 50 Hz motor mechanically coupled to a generator with 3 times less poles, which gave 50 / 3 = 16,666666...Hz (+/- a tolerance).
Actually the way most railways solved this is by just having their own power stations. SBB produces almost all its electricity itself.
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Old March 23rd, 2016, 11:39 AM   #3207
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Quote:
Originally Posted by MarcVD View Post
Unfortunately you do, because of insulation. If used under 3 kV, motors have to be insulated for 3 kV, including the wires in the motor coils.
That would be true if the motors were exposed to 3kV. They aren't, because when you add a DC-DC 'tranformer' that produces 1.5 kV for the rest of the train nothing changes. It is a stop gap measure though. Completely changing the train for 3 kV would be preferable.

Quote:
Originally Posted by MarcVD View Post
For that I would like to know your source because as far as I know,
the "internal power bus" of a multivoltage train is usually 1500V, not 3000.
The baureihe 145/146 have an intermediate DC circuit voltage of up to 2800V for instance. If you take a look at the electric schematic of the Taurus 1216 you see that in DC mode the overhead line is connected directly to the intermediate circuit. Both can be found at drehstromloks.de.
This wikipedia article states 'The N700 Shinkansen uses a three-level converter to convert 25 kV single-phase AC to 1,520 V AC (via transformer) to 3,000 V DC (via phase-controlled rectifier with thyristor) to a maximum 2,300 V three-phase AC (via a variable voltage, variable frequency inverter using IGBTs with pulse-width modulation) to run the motors.'
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Old March 26th, 2016, 01:02 AM   #3208
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Quote:
Originally Posted by MarcVD View Post
Unfortunately you do, because of insulation. If used under 3 kV, motors have
to be insulated for 3 kV, including the wires in the motor coils. The fact that they are used two in series doesn't change anything. Not doing it would be a major security hazard. So yes you might keep them, but then you need to
rewire them completely, which would probably be more expensive than
purchasing anew.



3 cases to consider :
- old equipment still using resistor sets : to be completely changed because of insulation reasons, like said above. But I suppose you don't have so much of
that anymore...

- DC serial motors with choppers : that I suppose you still have a lot of. Has to be completely renew because the thyristor chains have now to withstand a voltage of 3 kV rather than 1500 (but only half the current, so you need more in series and less in parallel)

3 phases motors : there you have more chances to be able to re-use most of the components, indeed.



For that I would like to know your source because as far as I know,
the "internal power bus" of a multivoltage train is usually 1500V, not 3000.
Let's see.
Resistor sets: Mat 64' (withdrawal planned next month), first 50 sets of ICM (withdrawal around 2022-2025)
Choppers: SGM (withdrawal planned 2018/2019), other 94 sets of ICM, built between 1987 and 1993

The rest is all three-phase.
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Old March 27th, 2016, 07:40 PM   #3209
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Old March 27th, 2016, 10:12 PM   #3210
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Weirdest train even, undoubtably (but also exceptionally comfortable)
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Old March 27th, 2016, 11:11 PM   #3211
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I like them as they are very comfortable, there are only a few downsides;
- really really small trash cans
- seat trays are kind of far away from the seat (akward to work on a laptop)
- very bright light

Plus:
- smooth
- lovely chairs
- design elements
- wide doors/stairs
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Old March 28th, 2016, 10:19 PM   #3212
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I really like the corner couches in these units.

I hate the fact that there is no positive lock when the door is closed or open, it just wildly swings about instead, really dangerous when people let go of them and the following person is unaware that it is going to swing into their face.
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Old March 28th, 2016, 11:18 PM   #3213
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I like the trains, but they have some construction problems, minor things like seats some seats that are wearing off too soon, or toilette doors that are misaligned etc.
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Old March 29th, 2016, 08:05 PM   #3214
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The first 3 Flirtīs arrived in Maastricht today.

https://www.facebook.com/NedTrain/ph...type=3&theater

3 generations.

Link

The new flirtīs got a revised livery around the doors.

Link

Also SLT will be refurbished (dutch) in 2017
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Old April 2nd, 2016, 12:31 AM   #3215
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Today the first NS Flirt made its first testdrive on Dutch soil.

Link

Also it looks like it won't take long for we see the first refurbished VIRM for a testdrive.
Here is VIRMm with a part of it's new livery and with the new European door livery guidelines which are also shown on the new NS Flirt.

Link
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Old April 2nd, 2016, 02:51 AM   #3216
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I saw also pictures of a R-Net Flirt, are they in test as well?
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Old April 2nd, 2016, 11:20 AM   #3217
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Yeah, those have been running past HS and Laan van NOI. If you'd still been living here, you'd have seen them.
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Old April 3rd, 2016, 02:31 AM   #3218
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The R-Net FLIRT has been making test runs for a few months now, they'll be entering service this december. The NS FLIRTs will probably see an earlier debut into service, as they are needed very quickly.
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Old April 3rd, 2016, 03:16 AM   #3219
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Is there any substantial difference between the two?

Quote:
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Yeah, those have been running past HS and Laan van NOI. If you'd still been living here, you'd have seen them.
Damn, the guy who got my room didn't have my same idea to put a webcam out of the window... I had the best view on the line
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Well, sir, there's nothing on earth like a genuine, bona fide, electrified, six-car monorail!

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Due to Photobucket f*cking up, most images won't be visibile in my old posts. If you need anything specific, please write me.

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Old April 3rd, 2016, 03:26 AM   #3220
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The only differences I could find is that they are shorter and don't have a cabin door.
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