Telegraph engineering : a manual for practicing telegraph engineers and engineering students (1922)
Hausmann, Erich, 1886- · New York : D. Van Nostrand Company · leaf 255
The consequent opening of the local circuit atthe relay sets the signal in the danger position. Thebattery and relay are placed at opposite ends of a tracksection, because this arrangement protects against brokenrails and also indicates open bonds between rail-lengths.Either primary or storage… … To D, Fig. II. their neutral armatures controlling the home signals andtheir polarized armatures controlhng the distant signals;the operation of a home semaphore blade moving a pole-changer for reversing the current in the relay of the pre-ceding block. This system is called the polarized or…
Telegraph
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