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Re: 220/230/240V 60Hz Systems [Re: dsk] #219695
10/09/18 05:27 AM
10/09/18 05:27 AM
T
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,436
Vienna, Austria
Originally Posted by dsk
Originally Posted by gfretwell
I think a 60hz motor would still run at 50hz but if it is an induction motor it will run hotter and slower.

That is correct, the 50Hz motors does hoften have more iron (are heavier) so temperature monitoring may be a good idea.
The speed of an induction motor will follow the frequency!


That's exactly the point of using higher frequencies, especially the 400 Hz in aviation. Transformers and motors can use much less iron and that means less weight. On the other hand if you need slow-running motors they need to have more poles than their 50 or 60-Hz equivalents.

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Re: 220/230/240V 60Hz Systems [Re: mel80] #219702
10/12/18 03:07 PM
10/12/18 03:07 PM
A
annemarie1  Offline
Member
Joined: Mar 2015
Posts: 75
england
When I was working in the test dept of a transformer manufacturer we made some 3 phase 400 cycle transformers they were tiny even the 5 KVA ones were easy to pick up not lime the 50 cycle ones which weighed a ton not literally but still heavy

Re: 220/230/240V 60Hz Systems [Re: annemarie1] #219704
10/12/18 05:50 PM
10/12/18 05:50 PM
Trumpy  Offline

Member
Joined: Jul 2002
Posts: 8,253
SI,New Zealand
Originally Posted by annemarie1
When I was working in the test dept of a transformer manufacturer we made some 3 phase 400 cycle transformers they were tiny even the 5 KVA ones were easy to pick up not lime the 50 cycle ones which weighed a ton not literally but still heavy

Yep,
This is why the switch-mode power supply has become so popular, the higher the frequency, the smaller the transformer you require.
I still have a pet hate of them things though, especially as far as things like RFI goes.

Re: 220/230/240V 60Hz Systems [Re: mel80] #219716
10/17/18 12:25 PM
10/17/18 12:25 PM
D
dsk  Offline
Member
Joined: Jun 2014
Posts: 87
Norway
The loss in the lines are greater with higher frequencies, that is one of the reasons for lo HZ train supply.
The other reason might have been at 16 2/3 hz a single phase motor works better.

I believe we have seen 25 and 40 Hz systems too, but not any more? Niagara falls might have had a 25Hz station?

dsk

Re: 220/230/240V 60Hz Systems [Re: mel80] #219737
10/28/18 10:14 AM
10/28/18 10:14 AM
T
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,436
Vienna, Austria
I think the main reason for 16 2/3 Hz was the motor issue, apparently large universal motors have issues with brush arcing at 50 Hz or more.
25 Hz definitely existed and in some rare instances still exists. Austria has a long-ish electrified narrow-gauge (1000 mm) railway line that was electrified in 1910 using 25 Hz. Originally the power station at Wienerbruck also supplied several villages along the line with electricity, today it's only for the railway itself but still 25 Hz.
For the most part Europe uses three different railway power systems, 15 kV 16.7 Hz in Austria, Germany, Switzerland and Sweden, 1.5 or 3 kV DC in a bunch of countries (France, possibly Belgium, Italy, maybe Spain, the Netherlands, Poland, parts of the Czech Republic etc.) and 25 kV/50 Hz (parts of the Czech Republic, the UK, Hungary, high-speed lines in Spain, etc.). I suspect 50 Hz AC is only common in countries that started late into the electrification process, mostly after WWI. Apparently the first Hungarian electric locos used ridiculously complex electromechanical control systems while the 16 2/3 Hz ones simply used transformers with a bunch of taps (very efficient) and the DC ones used series resistors.

Re: 220/230/240V 60Hz Systems [Re: Texas_Ranger] #219748
11/07/18 12:48 AM
11/07/18 12:48 AM
A
Albert  Offline
Member
Joined: Aug 2006
Posts: 78
Falls Church, VA
In the US, Amtrak (the national passenger rail service) operates a big 25Hz single-phase system, dating to the 1920s, for traction power between Washington DC and New York City, and between Philadelphia and Harrisburg, PA. It includes two dedicated 25Hz hydroelectric generators at Safe Harbor Dam on the Susquehanna River, motor-generator frequency converters in PA and NJ, and more recently, solid-state cycloconverters

See:
Amtrak 25Hz traction power system

Re: 220/230/240V 60Hz Systems [Re: mel80] #219772
11/21/18 09:04 PM
11/21/18 09:04 PM
D
djk  Offline
Member
Joined: Dec 2002
Posts: 1,241
Ireland
On railways 25kV 50Hz network frequency AC is normally found on high-speed lines as you need the high voltage to get sufficient power transmission to the trains.

A TGV set typically consumers about 8 to 10 megawatts, depending on the configuration. There were high speed test sets consuming 19 MW!!

In Ireland 1.5kV DC is used in Dublin's DART which was only electrified in 1983/84 and the Luas tram system which is a relatively modern Alstom Citadis based system uses 750V DC

The UK uses:

National Rail: 25kV 50Hz Overhead and 650 V - 750 V DC 3rd Rail.

1.5kV DC overhead Tyne & Wear Metro
750V DC overhead - Trams
750 DC 3rd rail bottom contact - Docklands Light Rail DLR
630V DC 4th rail - London Underground (top contact)


Last edited by djk; 11/21/18 09:04 PM.
Re: 220/230/240V 60Hz Systems [Re: mel80] #219775
11/23/18 06:30 AM
11/23/18 06:30 AM
T
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,436
Vienna, Austria
550-750 V DC are fairly common for urban systems where lines are relatively short and in the case of 3rd rail systems voltage drop is limited by the huge cross-section. Trams also need to be lightweight, installing a huge transformer isn't really an option. So low-voltage DC was a fairly natural choice, often directly fed to motors with series resistors and load resistors for generative braking. Only in the late 1970s solid-state motor controls were introduced but by then 550-750 V DC had already been well-established as the standard voltage for tram, underground and metro systems. These voltages are also less of a safety concern than 10+ kV and require much smaller insulators, keeping appearances in city streets tidier.

Why the DART uses 1.5 kV DC is beyond me, I think at that time there was already an international agreement to use 25 kV/50 Hz for railways unless there's a legacy system already in use in that country.

Austria is generally 15 kV/16.7 Hz for railways (introduced around 1900 for the Vienna - Bratislava interurban railway that ran as a tram in both cities and as a proper railway outside, changing locomotives from DC to AC in the outskirts of each city) but there are different systems - 650 V DC for most trams, 750 V DC for the Vienna Underground (both 3rd rail bottom contact and overhead wire), 850 V DC for the local railway Vienna - Baden (WLB) running with beefed-up Duewag tram cars and Bombardier LRVs and a few other DC systems for older electrified regional train lines. All new electrification projects are 15 kV/16.7 Hz except trams and underground systems.

Since all new rail vehicles use VFDs to drive the motors the frequency doesn't really matter anymore. Either the current is rectified at the substation and converted to variable-frequency AC inside the locomotive/motor car or it's rectified and converted to AC inside the loco. AC has the huge advantage of being able to use transformers and much higher voltages, limiting current and voltage drop. DC mainline railways use scarily huge overhead wires!

Re: 220/230/240V 60Hz Systems [Re: mel80] #219783
11/25/18 06:16 PM
11/25/18 06:16 PM
D
djk  Offline
Member
Joined: Dec 2002
Posts: 1,241
Ireland
DART has some odd systems. The original trains used on it were made by Linke Hoffman Busche but the traction motors and controls were done by GEC - they'd date from 1983 or so. Those coaches were later refurbished by Siemens and the rest of the fleet was built by Tokyu Car of Japan.

The DLR in London also used Linke Hoffman Busche but they're light rail.

In general Irish Rail specs tend to be quite different to continental Europe as the networks don't and won't ever interconnect. The gauge is wider 1600mm as opposed to 1435mm and there are significant differences in signaling systems. Ireland used track circuits with various frequencies to indicate the status of the next signal and speed. The system used on the DART actually allows for automation. There's no indication of any movement towards harmonised European signalling.

The only international services are to Northern Ireland and they just follow the same standards as we do so it doesn't make any difference.

I'd say they used 1500V DC because it was practical. The Tyne & Weir (Newcastle) Metro dates from around the same era also used 1500V DC

The recent tender for DART vehicles specified dual voltage 25kV AC & 1500V DC as there will be new electrified services put in place around Dublin.

There's some vague idea of electric intercity services to Cork and possibly Belfast. There's never been any long distance electric trains here. At present all long distance rail is diesel operated mostly by relatively new Hyundai built DMUs, except on the two more serious imywedify routes Dublin-Cork and Dublin-Belfast which use push-pull diesel with fairly high spec coaches. Top speeds are only 160km/h and the trains are only spec'd for up to 200km/h theoretical absolute max but the network limits them to 160.

It's a low density pop, the longest journeys less than 3 hours and there's no transcontinental type links so in generally it's a pretty low speed setup by European standards.

But I'd say all of the above is why they didn't really pay much attention to pan EU systems.

Last edited by djk; 11/25/18 06:19 PM.
Re: 220/230/240V 60Hz Systems [Re: mel80] #219790
11/26/18 07:31 PM
11/26/18 07:31 PM
T
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,436
Vienna, Austria
Well, there is ETCS but I suppose the implementation will take a while.

https://en.wikipedia.org/wiki/European_Train_Control_System

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