Electric Railways - Direct Current (continued)

The next major suburban development was the measurement of the 'wide electric' lines and the introduction of the double-deck train to N.S.W., starting with the 1962 series rivetted aluminium trailer cars which were specified to weigh no more, when fully loaded, than the corresponding 1927 stock single-deck steel trailer. The experiment replaced 120 old wooden bodied trailer cars and proved outstandingly successful; four experimental aluminium motor cars (each with different power equipment) followed. Credit for the original concept is due to R. Ritchie, the N.S.W. Railway's rolling stock design engineer at the time.

The next contract order was for all stainless steel 2-deck motor cars and the next for complete 2-deck trains, with four-motor equipment and solid state (static) auxiliary supply sets. Clearance measurement and introduction of longer, narrower double-deck interurban cars -fully air-conditioned, and fitted with large motor alternator sets to cope with the higher auxiliary loads and motor excitation in regeneration followed. The N.S.W. system has retained the two-deck electric train formula ever since. Victoria was unable to follow suit, not because of low overhead bridges but because of the tight clearances of bluestone platforms and throughplate girders on the City Viaduct. Instead, Victoria opted for a 6-car train of longer single-deck cars.

The final development of electric traction technology in Australia was the move from resistance-start mechanically switched camshaft control equipment to solid-state thyristor choppers. The latest Sydney stock (the 'Tangara' project) has called for a quantum jump in the traction control technology used in Australia. It remains to be seen whether the railway will adopt thyristor choppers, or take the major steps to gate controlled thyristor inverters and a variable voltage, variable frequency supply to 3 phase ac induction-type brushless traction motors. The latter technology was chosen by Adelaide for its 1985 order of diesel-electric suburban railcars -the first application of modern 3-phase traction to any diesel railcar fleet.

Australian Academy of Technological Sciences and Engineering