How come Japan didn't unify on 1,500 V DC for overhead electric power?

[kvp]

Essentially yes. For the 3rd i would add that they could have choosen 25 kV, like the shinkansen lines, because that was the best technology, but they didn't want to add another new standard to the cape gauge network. (besides the 1500V DC, 20 kV 50 Hz, 20 kV 60 Hz systems)

 

So far it seems to me that in the end, due to the common shinkansen/cape gauge tunnel they will need 25 kV cape gauge trains too, since switching back and forth between 20 kV and 25 kV is not efficient and safe.

[Sacto1985]

Reviving this really old topic, I wonder why given the rebuilding from the ravages of World War II, why JNR didn't just ditch 1500 V DC altogether from the middle 1950's on and standardize on 20 kV AC overhead power? The initial costs might be higher but not having the deal with so many electrical substations and more reliable operations in all weathers are important pluses. And you only need "dead sections" just west of Tokyo and just east of Itoigawa to accommodate the difference between 50 Hz and 60 Hz power.

Edited February 27, 2016 by Sacto1985

[kvp]

I think the following reasons might have played a role:

-already existing infrastructure and the possibility to run new and old stock

-the simplicity and low cost of DC power when used for multiple units

-existing tunnel, overpass and bridge clearences built for DC voltages or barely enough to accomodate DC catenary

-also if the number of trains running from a single substation is always above 1, then it could be cheaper to keep the heavy and large AC-DC conversion equipment stationary in a lineside building (in an emu, every motor car or married pair counts as one 'train')

 

A 101 series train with resistor control has around the same complexity, ease of maintenance and reliability as an emu capable tramcar built on 1930ies technology, just scaled up to higher performance. I think that using a cheap and reliable technology on an existing network allowed the fast and large scale expansion of the electrified train network in Japan. (this is the take a proven technology, make it reliable and mass produce it philosophy, also might have to do something with the saying of don't fix it if it's not broken)

 

I think with 1950-60-ies technology, EMUs favoured DC power while locomotives could use the extra power present with AC power. This is one of the reasons why shinkansen technology was revolutionary as it managed to make AC power usable with multiple units and cram everything under the floor while the first TGV and ICE trains were essentially just push pull loco hauled sets with locos on both ends. (TGV: bo-bo+bo power cars in cow-calf setup, ICE: bo-bo power cars that could even haul conventional stock, compare this with the all axles powered M-M' married pairs of the series 0)

 

ps: I think it was a big enough challenge to rebuild the existing network, expand it to electrify so many lines while building new and efficient trains. Btw. the last pre war DC commuter emu in Tokyo has been retied in 1996 having started with JGR, run through all the years of JNR and finally retired by JR east.

[Sacto1985]

The reason why I thought JNR would consider an eventual complete switch to 20 kV AC for zairaisen lines was the fact during American B-29 raids at the end of World War II, they pretty much wiped out a huge fraction of Japan's railway infrastructure, and having to essentially rebuild everything they might as well have made the leap to AC overhead power anyway.

[railsquid]

As with Germany, it wasn't the case that railway lines and infrastructure suddenly largely ceased to exist - lots of damage, yes, but much easier to get up and running with existing resources than think about introducing an entirely new, unknown and unproven system requiring investment simply not available.

[kvp]

At the end of ww2 only a few countries had high voltage AC technology (like hungary) but it was largely unknown technology. The first usabe emu variant was the first shinkansen in 1964 which was in development since the 1930ies. It wouldn't be possible without rebuilding Japan first.

 

On the other hand, existing tunnels and other loading gauge restrictions didn't disappear and high AC voltages (20-25 kV) have much larger requirements.

 

A good example was the DC tram system in Hiroshima. It was back in operation after 3 days as the main generating station and some of the trams survived and low voltage DC wires could be strung on poles relatively fast as they require no serious isolation. Rebuilding a DC network from scratch is easier, cheaper and faster. It was done in the UK where some AC lines were converted to DC south of London to standardise on a reliable technology.

 

Then came the shinkansen and a few decades later we have an AC technology that is small enough to fit into a cape gauge emu. After the war it was simply nonexistent and the smallest high voltage, single phase AC traction motor was the size of a van and only a single one could be fitted into a 4 axle rod coupled locomotive. (used on a single pre war standard gauge high speed line between Budapest and Vienna) The american solution using low voltage, low frequency AC was the relatively small GG1. In the end of the 1950ies, a french, swiss and german team managed to make high voltage AC traction small enough to fit a motor into a bogie and the rest (transformer and tap changer) into a normal locomotive. Some of these early AC electrics (hungarian V43 and japanese ED75 are still running). It took a bit to get this under the floor of a standard gauge wide body emu and the series 0 shinkansen was born. Original japanese plans were for a switch to standard gauge 25kV AC technology on newly built trunk lines with both passenger and freight starting in 1964. In the end Japan decided to keep the old DC network as well because it was rebuilt and greatly extended before a suitable AC technology was invented.

[Sacto1985]

(By the way, I'm actually amazed the HIroden was able to get their tram system running just three days after the atomic bomb attack. The destruction the the center of the city was so complete that they pretty much had to rebuild everything from scratch.)

 

I still wonder why by 1970--when the technology finally matured enough to fit AC overhead power equipment into an EMU--the Japanese, who were flush with money at the time, didn't go on an aggressive plan to switch to AC overhead power in any part of Japan that were subject to bad winter weather. For example, the Chūō Main Line west of Takao Station all the way to nearly Nagoya.

[railsquid]

Three words: "cost-benefit analysis".

[Sacto1985]

Three words: "cost-benefit analysis".

 

Well, that's true, too. By 1970, JNR had a large number of 115 Series EMU's running on the Chūō Main Line between Takao and Shiojiri. It would have cost way too much money to convert them to the 415 Series configuration for AC overhead power.

[SuRoNeFu 25-501]

For example, the Chūō Main Line west of Takao Station all the way to nearly Nagoya.

It because of one reason:

 

Height clearance

 

Trains that built for use under AC overhead lines had insulators with much larger amount than those built for DC overhead lines, and unfortunately the tunnels on Chuo Line that existed on Takao - Shiojiri - Nagoya section are way too small for accommodating AC overhead line equipments (and it would spent too much money on increasing the height of tunnel ceiling, either "pushing" the ceiling upwards or lowering the track by digging the tunnel's floor - even without converting the overhead line's power supply from DC to AC).

 

Because of this, JNR decided to left the line still using 1.5kV DC, but having the trains specially built with lower roof on the section where the pantographs are installed. This resulted in the creation of -800 subseries of JNR's DC rolling stocks, where this subseries is primarily used by trains that designed to be used on lines with lower height clearances (especially in the tunnels).

 

One of the example is the 115-800 series, where the lowered part of MoHa 114-800's roof is shown as in the following picture:

 

 

And with the larger amount of insulators that needed by AC-powered trains, it means that there is still not enough space between the mounting point and the contact wire itself...

 

CMIIW...

Edited February 29, 2016 by SuRoNeFu 25-501

[Sacto1985]

If I remember correctly, the 115's assigned to the Chūō Main Line were built in the middle 1960's on specifically for operations on that very line, especially to accommodate the tunnels between Takao and Kōfu Stations. And they still assigned to that line, too. Small wonder why given the state of equipment to accommodate AC overhead power, no wonder why the Chūō Main Line stayed with DC overhead power despite the advantages of using AC overhead power in the colder winters along the Chūō Main Line.

[200系]

I generally don't like to pick apart anyone's post for no reason, but  I feel like I have to respond to a few of the misconceptions presented in this thread. 

 

 

 

 

 why JNR didn't just ditch 1500 V DC altogether from the middle 1950's on and standardize on 20 kV AC overhead power?

 

Because they weren't in a position to wait for more then a decade to re-electrify/expand their DC network, as they needed the network up and running as soon as possible after the war to aid in rebuilding the nation? Because growing passenger numbers post-war meant they couldn't wait for years for the practical implementation of AC power to become available?

 

I sort of answered your question some time ago in another topic of yours: 

 

"J.N.R. had wanted to introduce commercial frequency AC power since the end of the war, even going as far as proposing to import the technology from France (the SNCF was on the foreground of commercial frequency AC traction at that point in time, as they where rapidly electrifying their northern network using a 25Kv 50hz, while using mercury rectifiers (as well as testing several other solutions) for their locomotives (BB12000 class). Later the introduction of the silicon rectifier improved AC traction even further.) but due to lobbying from domestic manufacturers, J.N.R. decided to go ahead with it's own AC program in the mid 50's. And a 20Kv 50/60hz (50hz in the north, 60hz in the south, 20Kv because that was the voltage level already used to supply the 1.5Kv sub-stations with) system was adopted. As DC electrification has proven to be more costly, the final sections still to be electrified (Northern Tōhoku, Hokkaido and Kyūshū) where to be using the 20Kv AC system. So this, in short, is why those regions use AC traction "   

 

Which is, in condensed form, roughly why the Japanese AC system came to be as it is today.

 

Or as railsquid said:

 

 

As with Germany, it wasn't the case that railway lines and infrastructure suddenly largely ceased to exist - lots of damage, yes, but much easier to get up and running with existing resources than think about introducing an entirely new, unknown and unproven system requiring investment simply not available.

 

Exactly.

 

 

 

A 101 series train with resistor control has around the same complexity, ease of maintenance and reliability as an emu capable tramcar built on 1930ies technology, just scaled up to higher performance.

 

Not really, the 101系 with it's introduction of the parallel cardan drive system (as opposed to the nose suspension drive system used on preceding J.N.R. equipment) was considered to be revolutionary enough (both in performance and in reduced maintenance costs) that all equipment using this drive system (anything after the 101系, with exception of the shinkansen, and until the TD drive became commonplace in the early/mid 1990's) was considered to be a well defined splitting point in Japanese railway history (the 'new performance' trains, while anything built before the 101系 (MoHa90形 originally) where referred to as 'old form' (officially) or 'getaden' (after the distinctive growling sound produced by the nose suspension drive, which was compared to the distinctive sound produced by traditional geta). As well as introducing the, now familiar, numbering system in 1959 which was a reaction to the development of several 'new performance'  classes after the 101系

 

 

 

single phase AC traction motor was the size of a van and only a single one could be fitted into a 4 axle rod coupled locomotive

 

We are confusing two different problems here, the first being the use of AC traction motors on railway equipment using industrial frequency AC power Or more importantly, the control system for said AC motors), while the other is the use of industrial frequency AC to power railway equipment. While they may sound similar there are some significant difference between the two (as I'm sure you are aware off).

 

The first problem, using AC traction motors could only be reliably fixed since the introduction of the asynchronous traction motors, and the related VVVF (variable voltage variable frequency) equipment needed to control said motors, in the mid 1980's (which J.N.R. started to experiment with, by ordering the experimental, GTO-VVVF equipped 207系 in 1986). Asynchronous traction motors using GTO-VVVF (and since the mid 90's, IGBT-VVVF) would become the standard for the majority of JR group EMU's, both AC and DC powered, introduced since the early 1990's (some private railway companies started introducing VVVF equipped equipment in the mid 80's).

 

The second problem, using AC to power electric equipment, could be reliably solved since the early 50's, by using a rectifier (first mercury rectifiers where used, and starting in the late 50's the lighter and more compact silicon rectifier) to step down the high voltage AC power to a usable DC voltage (either 3Kv or 1.5kv depending on the nation), which could be used to power a otherwise conventional DC traction installation for that period in time (cam shaft powered resistor control, controlling DC traction motors). This system was first used in France, when electrifying the main lines north of Paris in the early 50's, and it was this system which was introduced by J.N.R. starting in the late 50's.

 

Consequently, in the last few decades, with the universal adaptation of VVVF control systems we are now at a point where every EMU/EL built in the last 20 years uses AC traction motors, whether they use AC or DC overhead power.

 

 

 

The first usabe emu variant was the first shinkansen in 1964....

 

Actually, the very first Japanese AC powered EMU series where the 401系 (1.5Kv/20Kv 50Hz, first delivery in August 1960) and 421系 (1.5Kv/20Kv60Hz, first delivery in December 1960) both of these series starting mass production in mid 1961. They both used silicon rectifiers all mounted under the car body (the entire traction installation, including the main transformer and silicon rectifier, was mounted underfloor). The 451系/471系 and 453系/473系 ordinary express types where also introduced before the 0系 went into service as well (1962 and 1963 respectively).

 

 

 

...which was in development since the 1930ies. It wouldn't be possible without rebuilding Japan first.

 

The 0系 formations as built from 1964 onward had little to nothing to do with the original dangan ressha concept of the war years. The original designs for the dangan ressha where supposed to be twin electric locomotives, or as the war situation worsened for the Japanese, high speed steam locomotives (though to be fair, some of the designers kept working on EL concepts). the Shinkansen concept which would eventually become the 0系, was in it's self a (somewhat quickly designed) development of the two 1000形 test formations built in 1962, and was never intended as anything more then a stop-gap measure, until the intended 250km/h capable equipment was available.

​Of course history turned out differently (fortunately for me as a 0系 fan).

 

 

 

This is one of the reasons why shinkansen technology was revolutionary as it managed to make AC power usable with multiple units and cram everything under the floor

 

What was revolutionary about the shinkansen was the infrastructure, the 0系, though she was certainly state of the art, used mostly proven technology in an effort to create highly reliable and safe equipment (don't forget that before the opening of the Tōkaidō shinkansen there was a lot of skepticism about the project, both within J.N.R. and the diet).

The 0系 did introduce air spring trucks, air tight cars, closed toilet systems and of course the state of the art ATC-1 safety system. But in terms of the traction installation she was rather conventional, using powerful DC traction motors (MT200/MT200A (0番台/1000番台) and MT200B (2000番台)) controlled by a cam shaft powered resistor control setup (CS21 on the 0番台, CS46 on the 1000番台 and up) with the DC power supplied by a silicon rectifier. The drive system (WN-drive) had already been in use since the early 50's, mainly on the Tōkyō metro and some private railways, and the silicon rectifier setup had been in use for a few years on the aforementioned 401系/421系 and had proven to be extremely reliable therefore  more then suitable for the upcoming 0系.

 

In fact the first shinkansen to use AC traction motors was the 300系 prototype, built in 1990 (GTO-VVVF system) and used in all series afterwards (with exception of the 400系, which used conventional  traction motors controlled by a thyristor setup). While the E4系 was the first series to be entirely controlled by a IGBT-VVVF system (E2系0番台 and E3系0番台/1000番台 where mixed GTO and IGBT depending on the builder).

 

 

 

while the first TGV and ICE trains were essentially just push pull loco hauled sets with locos on both ends.

 

Both France and Germany where predominantly locomotive builders and didn't embrace the EMU concept in the same way that Japan did since at least since the 1930's, so it's no wonder that when they started designing high speed equipment they chose a configuration that their industry was most comfortable with (not to mention that the TGV-PSE was originally designed with a gas turbine in mind until the 1973 oil shock forced them to abandon this idea). There is no real engineering reason why they couldn't achieve the same performance using distributed power as opposed to the push-pull system.

 

 

Hope that answers any questions (going back into hibernation mode  ). 

Edited February 28, 2016 by 200系

[kvp]

I mostly agree but i would like to make a small addition.

 

High voltage AC locomotives don't need rectifiers and DC motors. The first variants developed in Hungary used an electromechanical VVVF converter to drive a 3 phase synchronous motor. It was huge, had 4 speed steps up to 125 km/h, but were very efficient. The second variant is the Ward Leonard drive that were essentially substations on wheels with very fine speed control and huge weight. The third variant used tap changers and universal motors that work both from AC and DC. The fourth variant was the rectifier version and i'm not entirely sure if the series 0 wasn't using a tap changer system. (some of the documents show tap changers) The controls are similar but instead of resistor banks, the tap points are changed by the servo motors. This provides direct voltage (speed) control instead of a fixed transformer and stepped resistor control used for some of the early AC systems, but makes it impossible to run on DC. Tap changing is more efficient too, with or without a rectifier bridge. (converting to dc helps with the problems of using higher frequency ac with universal motors, but fully optional if series wound universal motors are used)

 

ps: Cardan drives were in use on pre ww2 medium floor trams that didn't have space in the small bogies for the motors, so that wasn't entirely new either, it was more like a gradual evolution.

 

The oldest high speed emu design i saw was the 1930ies Ganz plan for a 200+ km/h set using 2 axle powered bogies on both ends, with a single synchronous motor driving each though a side linkage. The biggest problems were power supply capacity and axle loading, so 4 and 6 axle locomotives were built instead.

[200系]

kvp,

 

 

 

High voltage AC locomotives don't need rectifiers and DC motors.

 

Never said they did, nor did I mention locomotives anywhere in my response.

 

All I said, was that until the introduction of asynchronous AC traction motors and GTO-VVVF control systems in the mid 1980's the silicon rectifier/DC traction motor setup was considered to be the easiest, most reliable and most practical application of industrial frequency AC overhead power, and more importantly the system chosen by Japan (which is the main topic of discussion, not Hungary, not Europe, though even your mentioned MAV V43 uses silicon-rectifiers).

 

And I stand by that point.

 

 

 

The fourth variant was the rectifier version and i'm not entirely sure if the series 0 wasn't using a tap changer system. (some of the documents show tap changers)

 

 You are right, she was using a camshaft powered 25 stage low pressure tap system (had the 401系/421系 in mind when I posted my answer, so my mistake) however she most certainly didn't use universal motors.

However all of this is beside my point, which is that the 0系, despite the AC power supply, used a rather conventional DC traction motor setup (415v synchronous DC motors in a series/parallel configuration). and that point still stands. 

 

 

 

ps: Cardan drives were in use on pre ww2 medium floor trams that didn't have space in the small bogies for the motors, so that wasn't entirely new either, it was more like a gradual evolution.

 

First, I'm well aware of that, the cardan system I'm referring to, the BBC hollow shaft parallel cardan drive system was developed for a Zurich streetcar type (not sure which type, nor do I care too much) in 1941. and had been introduced to Japan in 1952 by what is now the Hankyū dentetsu (Hankyū 700系, 751 was used to test the Tōyō electric built drive unit).

And I'm also aware that other cardan type systems, like for example the right-angle cardan system used by the PCC cars (both pre-war and 1945/post war St Louis car co. types), where used before the introduction of the 101系 in 1957.

 

However, my point was never that the 101系 was the first train ever to use the parallel cardan drive system, nor that the system itself was somehow a revolutionary concept. My point was, and still is, that the 101系, by proxy of being the first J.N.R. EMU series to introduce this drive system (which became the standard drive system for nearly three decades in Japan), with it's advantages of lower maintenance costs etc etc, was considered important enough by the Japanese to be the starting point of a new railway era in Japan (i.e. anything built before the 101系 was considered old fashioned from that point onward (i.e. similar to the Dreadnought/ Pre-Dreadnought split in naval history). Therefore countering your point that the 101系 was simply a further evolution of the EMU classes introduced since 1929.

 

Also, I try to look at Japanese railway history/rolling stock development (or basically anything to do with Japan in general) through a Japanese lens, as opposed to the European (or more precisely, Hungarian) bias you seem to employ. This, for me, means that non-Japanese developments, unless they specifically influenced Japanese rolling stock development (like for example the mentioned WN drive, parallel cardan drive, or the import of American locomotive technology at the turn of the century (19th century) etc etc) are of no consequence in this context. Nor, to be honest, do I care too much about them (at least not when discussing Japanese railway matters, I'm kind of a purist in that sense).

 

-Sander

[kvp]

 

 You are right, she was using a camshaft powered 25 stage low pressure tap system (had the 401系/421系 in mind when I posted my answer, so my mistake) however she most certainly didn't use universal motors.

I think i didn't say it used them, i just remembered the tap changer technology. Somewhere i saw rather nice and very detailed pictures of the whole control system both assembed and disassembed. It was a pure AC system with very good performance and something that wasn't used on the mixed use AC/DC sets before. (actually i like simple and elegant solutions)

 

 

 I'm kind of a purist in that sense).

And that's good. I kind of like to compare various systems from various countries and their parallel evolution and how one thing influenced the other. Like how the bogie technology used on the 101 series was seen a few years earlier on newly developed hungarian cars and theorethically both are schlieren descendants but apparently the result of a parallel evolution:

-ancient kalaka3 standard gauge bogie: http://img.index.hu/imgfrm/4/8/4/5/BIG_0000724845.jpg (the brake cylinders are on the inner side)

-also old, but a bit younger cape gauge dt21 bogie: http://daisyanosekai.web.fc2.com/jnr-dt21b-n03.jpg (uses link bars instead of the chain links)

 

[hans-diesel]

the 3rd document on the folowing website may be of interest:

 

http://www.ejrcf.or.jp/jrtr/technology/index_technology.html