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THE EVOLUTION OF ELECTRIC RAILWAYS In the history of railways, those countries which had the courage to pioneer often reaped the benefits in selling their experience to other nations. So it is with the Swiss who built the world's first mainline electric railway system in 1906. In 1902 there was not one fullsize, long distance, fully electric standard gauge mountain railway in the world. In one tremendous act of engineering innovation a small Swiss company, the BLS of Bern, rewrote the book and added immeasurably to the world's store of electrical railway knowledge and experience. Just after the turn of the century, the citizens of Bern petitioned their government to build a railway. Their plea was rejected, as governments worldwide are wont to do. Often it seems the principal function of democratic governments everywhere is to refuse the sensible requests of their people. And just what so stirred the good folk of Bern? Well, the year was 1906 and the brand new Simplon tunnel was carrying railway traffic under the Alps from Switzerland directly into Italy for the first time. Holiday goers and business people were all enjoying the new short-cut to their neighbour's country. But for revellers and entrepreneurs alike, to live in the national capital, Bern, was to be penalised. Their city was on a dead- PT.7 THE FIRST ELECTRIC MAINLINE SYSTEM 76 SILICON CHIP LEFT: THE BERN-LOTSCHBERGSIMPLON railway was the world's first electric mainline and also the first to use AC. The line is shown here between Lalden and Brig on the south slope down from the Lotschberg Tunnel. Photo courtesy BLS. end in the national railway scheme. Residents of the larger city Zurich and the smaller cantons Basel, Geneve, Lauzanne, Luzern, even Sargans and Brig, found that the European world came to their doorstep, and vice-versa. Switzerland was fast becoming the railway crossroads of Europe, and those other lucky Swiss cities were on the National Trunk Railway System which more or less circled around their mountainous country. Connections to other cities of the continent radiated out like spokes of a wheel and now the Simplon tunnel through the Alps gave an even shorter path into Italy. This meant good business for the Swiss. But not for Bern, placed as it was off the main railway. Thus the petition whereby the people of Bern requested the government to build a short railway, a mere 120 kilometres long, from Bern to meet the northern end of the new Simplon railway tunnel at Brig. Not surprisingly, the government refused. For standing in the way of the proposed railway was a huge branch of the mighty Alps, running half of the length of the country from south-west to north-east as an enormous barrier between Bern and the Rhone river. Including the 4170 metre high Jungfrau and the 4180 metre high Aletschhorn peaks, nature had strewn any proposed route with high cliffs, glaciers, mountain lakes, deep chasms, snow and ice, all prone to landslides and avalanches. "Let our Government-owned rail system continue to go around them, as our faithful steam locomotives and high-class trains do at present, via Lausanne or Zurich on the government lines'', was the government's response. The BLS company But the Swiss are determined, ingenious types. The citizens of Bern THIS VIEW SHOWS A BLS high-speed electric train on the line near Eggerberg, descending from Lotschberg Tunnel. The train has a maximum speed of 140km/hr. (BLS photo). formed a public company, the BLS (Bern-Lotschberg-Simplon). Shares were sold, capital collected. The conception of the trans-alpine railway dated from as far back as 1866, now they would build it. Yes, they would build their own railway direct from Bern to Brig where it would join the new existing Simplon tunnel entry into Italy. Construction began in 1906 at Spiez and proceeded up the Kander Valley towards Kandersteg. From Frutigen to the high valley town of Kandersteg the line was constructed to rise continuously for 20 kilometres at a ruling gradient of 1 in 37. That might not sound much but the track also negotiates the 46 metre high Kander river viaduct, a 265-metre long beautiful example of the stone-mason's art, and two complete corkscrew circles in a zigzag pattern (one circle mostly within a tunnel), to bring trains up the cliff face to meet the main trunk of the mountain range. At the same time, drilling of the 14,612-metre long Lotschberg tunnel through the range began. As the tunnellers toiled deep within the mountain they pierced an unsuspected vertical fault in the rock strata whereupon, in a few horrific seconds, 25 men perished in the fall, along with all the equipment. The only thing to do was tunnel around the fault, a course which involved the introduction of three extra curves and the abandonment of more than one and a half kilometres of tunnel already drilled. Construction of the 26km long southern ramp from the southern end of the tunnel at the Lotschental river crossing down to Brig on the Rhone river was simultaneously undertaken. This southern approach to the tunnel, though different from its northern counterpart, is no less spectacular. The southern track has to cross many rivers, deep ravines and three icy valleys, including the tail ends of the Jolital, Bietschtal and Mankin Glaciers. MAY 1988 77 SPECTACULAR SCENERY: A BLS TRAIN CROSSES the new reinforced concrete viaduct over the Kander River. Behind the new viaduct is the original stone masonary Kander Viaduct which is some 46-metres high. The new concrete structure is part of a 10-year project to double-track the entire line. (BLS photo). Added to the breathtaking beauty of nature in this region is the ingenuity of man. Still geologically active, the Alps include many deep clefts whose sides are sheer rock faces hundreds of metres high, making the construction of a railway difficult in the extreme. Tunnels were bored from both sides towards the cleft, then a bridge had to be constructed joining the opposite tunnel openings in the cliff walls, high above the ice or river below. One such is the famous Bietschtal arch featured on many European postcards. On the Bern or northern side of the Lotschberg tunnel the approaches rise 680 metres to a height of 1240 metres above sea level in the centre of the tunnel. Then the southern ramp falls over 500 metres to its crossing of the Rhone river at Brig, joining the Swiss Federal Railways. From here 78 SILICON CHIP the government line enters the Simplon tunnel on its way to Italy. Major constructions Including the Lotschberg tunnel, the line from Bern to Brig required the drilling of thirty four tunnels a total of 27 kilometres long. Also necessary was the construction of 25 difficult bridges and viaducts as well as ten avalanche galleries, safety walls and terraces many kilometres long to protect against landslides and snowslides. To decrease the risk of avalanches burying the line, the company planted ten million trees on 386 hectares of mountain slopes. The Lotschberg tunnel, begun in 1906, was drilled wide enough for double track from the start and completed on March 31, 1911. It is one of the world's longest and, at 1240 metres above sea level, is the highest standard gauge tunnel in Europe. (An interesting aside is that Australia's own standard gauge railways reach a higher point, 1377 metres above sea level at Ben Lomond in New South Wales. Of course other Swiss private narrow gauge lines rise much higher, to almost 3600 metres.) Without sufficient funds for a totally double track line, the northern and southern approaches were constructed single track with crossing loops. However, some bridges, such as the Bietschtal main arch, were built to double track width. Most tunnels had the complete roof arch cut in anticipation of eventual double tracking. The complete line was opened for traffic on June 15, 1913 allowing through trains from Italy to all of Europe to run via Bern. Today you may even extend your train journey all the way to London. r------- ----------- I I r- - 7 J I I I j J CAB I I iE\~N~~i PRIMARY 15kV I I I ~---....J SECONOARY 200-500-1000 V 15 5 - Hz I II I j I I j I ORIVE ROO I L __ _j .J k-L - - - 0 v-----~ ,------C~-_:~~~~~----..'r---"--~ 1 I coNrnoLLERs TRANSFORMER - - 7 I _t J I L__ _J I _.,.__..___~~'----!---__,c;_-~-----""---~-,c:__- kV RETURN '<c-----.---r----=-~+--'--"c......+--r--~---rr---=~--r---= - - - - LEADING BOGIE 10 DRIVING WHEELS J 0 L J- ~ TRAILING BOGIE FIG.1: OUTLINE SKETCH OF AN early BLS 2-10-2 electric locomotive. External drive rods were used to couple the 10 driving wheels in the same manner as on steam locomotives. THE BLS ELECTRIC LOCOMOTIVES USE A DIAMOND style pantograph to pick up current from an overhead contact wire carrying 15kV 16.6Hz AC. (BLS photo). The total cost of the line's construction was 138 million Swiss Francs of which over 52 million Swiss Francs were expended on the drilling of the Lotschberg tunnel. With clever design and construction effort the average grade was held down to 1 in 48 and the ruling grade (maximum incline) to 1 in 37, allowing heavy trains and high running speeds, provided high powered locomotives were used. By comparison, some other lines in Switzerland rise much more steeply, as steep as one in four. First electric mainline Constructed from the start as a fully electric line, we must marvel when we recall that this electrical engineering design work was being done when there was no previous high-power long-distance electric traction experience to ref er to. The BLS engineers had to personally invent the electrical concepts and gain the experience, and thereby established themselves as the world's leading high voltage AC railway traction consultants during the next twenty years. First AC locomotives Taking a cue from standard mountain steam locomotive practice of the day, by 1910 the electrical engineers had built an electric locomotive having the same wheel arrangement as for a 2-10-2 steam engine (ie, one pair of leading small bogie wheels, a mainframe carried on ten large driving wheels on five axles, followed by two small bogie wheels). External drive rods coupled all five driving wheels on each side in the same manner as on steam locos. Within the locomotive body, carried on the mainframes, one large commutator AC motor was either gear coupled or rod coupled to one driving axle, from which the external drive rods transmitted driving forces to all ten coupled wheels, as in our outline sketch (Fig.1). This basic design, known simply as a 'Rod Drive Electric Locomotive', became the standard for high-powered medium speed electric locomotives for many years, a design adopted by those few other railroads that dared venture into high-power mainline electric locomotive design in the period from 1906 to 1950. The Virginia Railroad of the USA and the Swedish State Railways were two such railroads Eventually the BLS superseded the rod drive principle in favour of modern bogie electric loco design, to obtain higher running speeds. It is interesting to note that the unbeaten world record for locomotive tractive effort was established by a rod-drive electric locomotive of the Virginia Railroad. Examples of rod drive electric locomotives were still highly valued MAY 1988 79 ELECTRIC RAILWAYS - CTD and running until recent times, on such famous railroads as the Pennsylvania Central, the Virginia RR and the Lapland Railway. Some of these locos run even now. DC or AC? Because of the fairly long length of the Bern-Lotschberg-Simplon line, the engineers had to break away from the standard DC practice of the day. In Germany and in London at that time, short distances were covered by electric trains running on 750 volt DC third rail systems, taking their power from steam-driven generators. But the proposed high power electric locomotives of the BLS would take extremely large currents at such a "low" voltage as 750, leading to excessive line voltage drop and regulation problems. Therefore, a much higher voltage system, 15,000 volts, was adopted. We should note that the BLS had no quarrel with the principle of direct current per se, for the driving of traction motors. Far from it, for even today the DC series motor has the greatest shaft-torque/ armature current ratio. In this type motor alone, the shaft torque (and hence the loco tractive effort) is proportional to the square of the armature current. Hii h starting currents hence give enormous starting tractive effort, even more than can be transmitted by the driving wheels to the rail. Hence the continued use of this system around the world, including Australia. Hydroelectric plants Also we must remember that most of the electric power in Switzerland comes from hydroelectric plants where falling water turns turbine-driven alternators. Such plants naturally must be sited at the river, dam or waterfall, perhaps a long distance from the rail track, exacerbating voltage drop problems. In the very early 1900s, AC or Alternating Current was only just 80 SILICON CHIP being developed as an alternative to DC for street lighting and industrial uses. No one had even considered its use in high powered long distance rail traction. In 1906, the year construction of the line began, one could search the world to even find a power line 120 kilometres long, much less a system of railway overhead contact wires, catenaries and feeder lines of that length. AC chosen The Swiss engineers decided to adopt 15kV AC as their overhead contact wire system, and to step that voltage down using a large transformer carried in each locomotive. The transformer secondary would supply the loco's traction motors at a convenient voltage between 500 and 1000 volts. Their traction motors were series motors with commutators and brushes, identical to the motors used by other railways on DC except that, to minimise eddy currents in iron, the whole magnetic yoke and all pole pieces were of laminated steel (rather than the cast iron used in DC motors). Interpoles were used to improve the commutation (that is, to reduce arcing between brushes and commutator). Interpoles are small series wound poles placed between all main field magnet poles, as in Fig.2. Their function is to cancel the distortion of the main magnetic field caused by the magnetic field of the armature currents. Such field distortion would cause arcing under the brushes. The engineers found that their traction motors would not run well on AC supply at the standard 50Hz frequency and arcing occurred under the brushes, burning both brushes and commutator. This was because the inductive reactance of the field windings, armature coils and interpole windings caused phase delays, preventing the interpoles from properly cancelling the aforesaid distortion of the main fields. Solving the brush burning problem clearly meant reducing the in- THE FAMOUS 46-METRE high Kander Viaduct. This beautiful example of the stonemason's art is 256 metres long. (BLS photo). ductive reactance of all motor windings. This reactance is proportional both to frequency and winding inductance. As reduction of inductance was not the way to go, they took the innovative step of reducing the frequency to one third of the previous 50Hz, to 16.6Hz. This was a brave decision, as it TELEPHONE EXTENSION LEADS The very best available. Six conductor telephone lead, fully Telecom permitted (C85n/44) with standard plug and socket. Suits all telephones. Choose ten or fifteen ---:::::~§~~ metre lengths. Standard ivory colour with full three year guarantee. (10 metre T5016, 15 metre T5017) CORDLESS TELEPHONE MP-25O Telecom permitted (C86/35/34). Features call facility battery level indicator, mute and redial. Excellent reception and transmission range of up to 250 metres. (T4000). REMOTE ANSWERING MACHINE The very latest design using microprocessors to ensure reliability and trouble free operation. Featuring beeperless remote control - access your machine and messages anywhere in the world simply by using pre-programmed voice patterns. 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They would need a completely separate system of power lines, feeders, alternators, switchgear, protection and all the paraphernalia of a full electricity system. Undaunted, they proceeded. To obtain their low frequency 16.6Hz power supply they had (and still have) two alternatives: • Method (1) was to build separate power stations (or sections of power stations) specifically to generate the low frequency supply. At that time, their trains would probably use more electricity than most other users, so it would be sensible for the railway to build its own power stations. Compared to a 50Hz alternator, the 16.6Hz alternators would either run at one third the speed, or have one third as many poles. • Method (2) was to build normal 50Hz power stations, which could be interconnected to the growing electricity system of the rest of the country and run 50Hz 3-phase transmission lines to various trackside substations. Within these substations the 50Hz supply could be converted to 16.6Hz supply. In 1906 the only method available for such a frequency conversion was to use a 50Hz 3-phase high voltage synchronous motor direct-coupled to an alternator which generates the low frequency 16.6Hz supply. Frequency changing As new ways for frequency changing were invented, such as the later German invention of frequency division by "cycloconverters" whfch used banks of controlled mercury arc rectifiers, the natural tendency was to gradually shift from method (1) to method (2). Not only the BLS, but the great majority of other electric railways of the world which followed them at some time chose method (1) initially, only to slowly shift to method (2) over many years as new and better technology evolved. Some countries, for example Australia's own SRA, finally changed to method (2) only in the 1960s and 1970s when very large solid state controlled 82 SILICON CHIP THE LATEST HIGH-SPEED COACH bogies for electric trains feature disc brakes, side-sway shock-absorbers and roller bearings. In addition, the axle box can move sidways to allow both axles to self-align to the radius of curves, thus permitting higher running speeds (ie, the axles can point to the centre of the track curve for minimum friction). rectifiers (thyristors) became available. We observe that method (1) is the cheaper way (less large equipment) but method (2) is the more convenient. Some readers will want to know why method (2) is more convenient. First, there is the nicety of being able to interconnect to other 50Hz power generating systems, a handy aspect in the event of power station breakdown. Second a new railway must build stations, and these will want lights; on platforms and in buildings, and in the railway workers' homes, trackside workshops, goodsheds and ancillary buildings. But filament lamps operated on low frequencies like 16.6Hz give severe flicker problems. If the low frequency railway supply is all that is available at a location, the only cure is to use quite INTERPOLE - low voltage high current lamps, hoping that the heavier filament wire used will not cool down so much from one cycle to the next, so that the lamp brightness will not flutter so much. Other countries eventually faced the same problem. In Australia, at the Bullock Island railway yards, the original yard lighting system used 60 volt 20 amp lamps, in the hope that the heavy filament would reduce the flutter in brightness when operated on a low-frequency 25Hz system. Train control The original method of starting and controlling train speed was by switching resistances in series with the traction motors. All resistance is placed in the circuit to control motor current when starting, the driver gradually switching out sections of resistance as the speed in- ~ ~t~~ a,.::::=---a:::::,.,1 - ArJ:~nRE ~:~ . . . "-<> M INTERPOLE - ~ ~ MOTOR FRAME "'~" FIG.2: SERIES TRACTION MOTOR with four main field poles and four interpoles. The interpoles reduce arcing between the brushes and the commutator. creases. At full speed all resistance is switched out of circuit, to place the motors directly on the line. With high voltage AC operation the locomotive carries its own stepdown transformer on board. This gives the second option of switching to lower voltage tappings on the transformer secondary for starting. This wastes less power and uses less current from the line for starting, but the transformer is somewhat more expensive. The BLS engineers found by hard experience some control system facts not previously known to the world. We keep in mind that the BLS is a mountain railway, and that there will be some trains going uphill and others going downhill in other sections. A train using full power on a level section may come to a downhill grade and find its downhill speed held in check by another train ascending the hill in another section. The downhill train is actually generating electricity, driven by gravity and its own mass. Such generation is today called "regenerative braking" as it causes Did you a useful braking effect on the downhill train. This generated current feeds the other ascending train (rather than the current coming from the power station) if the power station is far distant. Troubles occur when the ascending train suddenly stops at a station or crossing loop. The decending train suddenly loses its electric braking and must resort to its air brakes for control. The moment the ascending train shut off its motors some of the current still generated by the descending train would flow back to the power station and momentarily drive the power station alternators. The power station water-turbine speed controller would then have to fight for control of the overspeeding turbine. In the early design and trial years, the BLS electrical engineers gained very valuable experience in the design and control of large high voltage dynamic loads. Such knowledge and expertise placed them in the forefront of the electrical world for decades to come. In company with the Swiss • IIllSS private manufacturing companies Brown, Boveri & Cie; Schweizerische Lokomotivund Maschinenfa brik; and Verkehrshaus der Schweiz; the BLS advanced the world's store of knowledge in the design and operation of motors, locomotives, power stations, and dynamic control systems for large heavy-haul long-distance ACelectric railways. Enter bogie locomotives For many decades, right up to the 1950s, the rod -drive style locomotive was predominant. Modern Swiss locomotives now are bogie types, in line with the rest of the world. These modern locos come in powers up to 10 megawatts (13,400 horsepower) and feature a variety of drive systems from thyristor controlled DC motors to 3-phase gearless axle mounted induction motors. How all these operate in various parts of Europe from a single phase AC of either 50Hz or 16.6Hz or DC overhead contact wire is another fascinating story. We'll have a look at that next month. ~ these issues? Issue Highlights February 1988: 200 Watt Stereo Power Amplifier ; Deluxe Car Burglar Alarm ; End of File Indicator for Modems; Simple Door Minder; Low Ohms Adapter for Multimeters. Please send me a back issue for □ November 1987 □ December 1987 □ dftl'ltlflFY 1 QaS (Sold Out) □ □ February 1 988 □ March 1988 April 1988 Enclosed is my cheque or money order for $ ...... .. or please debit my □ Bankcard □ Visa Name ... .. ..... ... .... ........ ... .. .... ...... ........ . ....... .... ... ..... .. ....... .. ...... .... .. . Address ....... .... ....... .... .... ..... .. .......... ... .... ...... ........ .... ........ ... .. .. .. .. . Suburb/town ... .. .. ... ......... ... ... ... .... ... .. .... ..... ... ... Postcode ... ............ . Card No ... .... ..... .. ........ ...... .... ... .... ........ .......... ...... .... ... .. ... ......... ... . March 1 988: Remote Switch for Car Alarms; Telephone Line Grabber; Low Cost Function Generator; Endless-Loop Tape Player. April 1 988: Walkaround Throttle for Model Railroads; pH Meter for Swimming Pools; Slave Flash Trigger; Mobile Antennas for the VHF & UHF Bands Price: $5.00 each (incl. p&p). Fill out the coupon at left (or a photostat copy) and send it to : SILICON CHIP, PO Box 139, Collaroy Beach 2097. Signature ........ ...... ...... .... ..... .... .. .. .. ..Card expiry date ... .. . ./ ...... ./ .... .. . ~------------------------~---------------~ M A Y 1988 83