Electrics in the diesel age: Postwar optimism
Electrics in the diesel age: Postwar optimism
First part – Electrics in the diesel age
While the war delayed any additional electrification, it helped accelerate some technological developments that promised to make it more attractive than ever before.
Most important by far was the development of practical rectifiers for locomotives, an advance that resolved several longstanding problems. The industry had long debated the relative merits of single-phase A.C. vs. D.C. High-voltage, single-phase A.C. provided substantial efficiencies in power distribution, while low-voltage D.C. traction motors offered the best control and performance characteristics. The rectifier, which permitted the efficient conversion of A.C. to D.C. power, made it possible to combine the best of both systems. Previously, too, the large single-phase motors used for A.C. electrification had required the use of low-frequency power. With rectifiers, the catenary could be energized with 60-cycle current directly from the commercial power grid, eliminating the costly substations, conversion equipment, and separate transmission lines that had been required for A.C. electrification.
Another handicap to electrification had been the anticipated unbalanced power loads that would have resulted from powering large, single-phase railroad electrifications from the three-phase commercial power system. The growth of the electric power market after World War II, however, minimized this potential problem, and the threat of unbalanced railroad power demands ceased to be a major deterrent.
Even dieselization, which rose in the late 1930’s as the principal rival to electrification, brought developments that were seen as helpful to electric power as well. Since they were, after all, simply electric locomotives that carried their own power plant with them, dieselelectrics incorporated a number of components common to straight electrics. Thus, the mass-production techniques that the diesel builders applied to locomotives for the first time developed rugged, efficient, low-cost traction motors, trucks, drive systems, controls, and other components that were equally applicable to straight electrics.
Diesels could help in another way, too. In the pre-diesel era the full economic advantages of electrification could be realized only through the complete replacement of steam power and its costly servicing and maintenance facilities. To do this, electrification had to include yard tracks, branches, another lightly used trackage at great additional cost. But by operating such secondary trackage with diesel power, which required less expensive servicing facilities, it became possible to confine electrification to the main running tracks.
With all these new advantages, together with emerging technologies, there was much talk of renewed electrification in the postwar years. Surveying the potential market for electrification shortly after the war, Earl Bill, manager of General Electric’s railroad rolling stock division, identified electrification projects totaling 1200 route-miles that were then under consideration. Most were additions to existing installations, including an extension of PRR catenary from Harrisburg to Pittsburgh, the New Haven’s long-deferred New Haven — Boston electrification, extension of Great Northern’s Cascade electrification into Seattle, and — the longest of all — a New York Central electrification from Harmon, N.Y., to Buffalo. An entirely new electrification under discussion would have put the Denver & Rio Grande Western under catenary through the Rockies.
In the Pacific Northwest, there was talk of low power rates from federal hydroelectric power plants and government investment to supply power at the trolley wire on as many as 8000 miles of line. Similarly, the Tennessee Valley Authority was looking at railroad electrification as a new market for its power generation plants.
“Currently there is enough interest in electrification so that should the projects materialize into actualities the electric locomotive manufacturers would be unable to handle the business,” commented Bill.
New technology brings new motive power
While there was no immediate action toward new electrifications, there were some interesting applications of new technologies on existing systems.
The first electric locomotives ordered after the war represented what was essentially an “old” technology. Needing additional power for their single-phase A.C. electrifications, both the Virginian and Great Northern placed orders with GE for what would be some of the largest electric locomotives ever built. Instead of trying the new and as yet unproven rectifier technology to convert high-voltage A.C. power from the trolley wire to low-voltage D.C. for the traction motors, both orders employed the older concept of motor-generators to accomplish the same thing. GN’s two streamlined W1’s, delivered in 1947, were enormous 101-foot-long, 360ton B-D+D-B units with a continuous rating of 5000 h.p. that ranked as the largest singleunit electrics ever built. Virginian’s four EL-2B’s, also streamlined, were made up of paired BB+BB units that were 150 feet, 8 inches long and weighed 517 tons. Each EL-2B set was rated at 6800 h.p.
Impressive as these new locomotives were, they were technological dinosaurs. Both of the principal suppliers of electric motive power, GE and Westinghouse, soon came forth with new experimental units for the PRR that were seen as prototypes for the anticipated new electrification market.
During 1951, GE delivered six Pennsy E2b-class units that, with their carbody design and BB wheel arrangement, were based upon contemporary diesel-electric practice and ideas GE engineers had developed for a “standard” locomotive for new U.S. electrification. But instead of employing the new rectifier technology, with D.C. traction motors, GE used A.C. commutator motors similar to those employed on earlier PRR electrics. Operated as two-unit locomotives, the E2b’s could produce a continuous output of 5000 h.p.
In 1949 the PRR had equipped one of its MP54 M.U. cars with an experimental ignitron-rectifier, with encouraging results, and the same technology was selected for a pair of experimental two-unit, 6000 h.p. locomotives delivered by Baldwin-Lima-Hamilton and Westinghouse during 1951 and 1952. Otherwise identical, two class E3b units had a BBB wheel arrangement, while two E3c units had a CC arrangement.
Both experimental designs worked well, but the Westinghouse ignitron-rectifier design was particularly successful. While the Pennsy delayed the replacement of its aging P5a locomotive fleet for almost another decade, other electrified roads soon adopted the new technology. The New Haven was the first, with an order for 100 Pullman-Standard M.U. cars in 1954 that were equipped with Westinghouse ignitron rectifiers.
Despite the Westinghouse success with its experimental ignitron-rectifier units, GE came up with all the locomotive orders. In 1955 GE completed 10 4000 h.p. E40 electrics for the New Haven. These EP-5’s, as the NH called them, were the first production model rectifier locomotives to operate in the U.S. The Virginian followed suit with an order for a dozen 3300 h.p. CC ignitron-rectifier units from GE. Arranged in the same road switcher configuration typical of diesel-electric practice, each of the E33’s (VGN class EL-C) weighed 174 tons. Beginning in 1960, GE delivered what would be its last big order for electric motive power, a fleet of 66 4400 h.p. E44 units that were essentially an advanced version of the earlier Virginian E33’s. The last five units delivered had newer air-cooled silicone-diode rectifiers, which were both simpler than the ignitron rectifiers and permitted an increase in output to 5000 h.p. Subsequently, the entire E44 fleet was converted.
The E44’s were prodigious performers that ably demonstrated the capabilities of modern electrification practice. The 66 units had been intended to replace all 92 of the Pennsy’s older P5a’s. In practice they proved capable of more than half again as much work per unit-month as a P5. Even before getting the upgraded rectifiers, the E44’s were able to handle 20 percent more drag freight tonnage than either a P5 or a GG1. Availability, even during the break-in period, was nearly 92 percent. Maintenance costs were only onethird of those for the P5’s, and only 25 percent of those for diesel-electric power in the same service.
The Pennsylvania acquired its first rectifier-equipped M.U. cars in 1958, and over the next decade large fleets of similar equipment were ordered for both PRR and Reading commuter services at Philadelphia, and for the Pennsy’s New Jersey services.
Third part – Electrics in the diesel age: What went wrong?
By William D. Middleton
William D. Middleton. Classic Trains, spring 2001, p. 22-29.
WILLIAM D. MIDDLETON has written extensively about railroad electrification. This article was adapted from the second edition of his book “When the Steam Railroads Electrified”, to be published later this year by Indiana University Press.