Short Circuit Protection: Challenges in the Early Years [History]

During the evening rush hour of 24 July 1903, New York City's Manhattan Elevated Railway experienced a shutdown that began in its 74th Street power station and quickly involved the entire system. This station, one of the most advanced of its time, had been in operation for only seven months. It contained eight 5,000-kW, threephase, 25-Hz, 11,000-V alternators driven by reciprocating steam engines. Figure 1 shows one of these vertical steam engines with the large-diameter multipolar alternator attached. A frantic effort returned operation by late evening. However, just before midnight, another major system fault occurred. The trains were running again within 24 h, but the cause of the shutdown was unknown and resulted in much speculation in the engineering press.