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On autotransformers

01 Jan 2001

Sir - The article on catenary upgrading on the West Coast Main Line (RG 11.00 p735) was extremely interesting, but there are, however, always pitfalls in making claims for 'firsts'.

Sometime in the mid-1960s Railway Gazette published an article, based on Japanese sources, reporting on the development of a 'new' electrification technique being used on an extension of the Shinkansen, using an autotransformer power supply. Shortly afterwards, you published a letter from Mr Harry Brown, electrical engineer of the New York, New Haven & Hartford Railroad, saying that the autotransformer scheme should be quite successful. He knew, he said, because it had worked well when he installed it on the New Haven line in 1911, and it was still working well at the time he wrote.

The electrified portion of the New Haven main line extended from New Haven, Connecticut, to New Rochelle, New York, and there divided into several branches reaching various points in New York City. This territory was electrified between 1907 and 1914 using 11 kV 25 Hz, and as noted, after 1911 was fed on an autotransformer system.

These lines were four-tracked (a short section was six-tracked), and handled a heavy traffic of long-distance passenger trains, through and local freight trains, and suburban passenger trains operated with EMU cars.

Thus, it can be seen that the New Haven installation somewhat preceded the WCML as a multi-track route with mixed traffic supplied by an autotransformer system. Since the 1960s, through freight operation on the New Haven line has largely been transferred to other routes, local freight has been dieselised, and portions of the line have been reduced to three tracks. The electrification has been changed to a 12 kV 60 Hz supply, but the original autotransformers are still in use today.

Henry T Raudenbush

Strafford, Pennsylvania, USA