Short circuit currents of the SEPTA traction power distribution system

A Monovoltage Equivalent Model of Bi-Voltage Autotransformer-Based Electrical Systems in Railways

“…The 2 25-kV system used in many new lines is a typical symmetrical bi-voltage AT-based system [6]. SEPTA's autotransformer system is a very illustrating example of an asymmetrical bi-voltage system in which 12/24-kV autotransformers [7] are used (see Fig. 4).…”

“…), the impedance matrix is always symmetrical . For that reason, when this transformation is used, (4) becomes (7) In these cases, the equivalent zero-sequence and direct-sequence model are represented in Fig. 6.…”

Modelling, simulation, and verification for detailed short‐circuit analysis of a 1 × 25 kV railway traction system

“…This paper examines a single‐phase 1 × 25 kV RTS in which the key factors determining the fault current are as follows: The short‐circuit capacity (SCC) at the busbar on the primary side of the traction transformer; that is, the source transformer. The winding connections (Le Blanc) and impedance of transformers in traction substations. The self and mutual impedances of overhead contact systems (including overhead messenger wire, overhead trolley contact wire, and return feeders) as well as the rails. Estimating disturbances resulting from the various types of short‐circuit faults require comprehensive data collection with regards to all major components and the overall RTS, while the operating conditions of the RTS (both normal and abnormal) must also be considered. In the technical literature, several studies have been performed on: (i) traction system design, components modelling, and calculation methods [6–11] and (ii) critical and short‐circuit conditions [12–15]. A detailed short‐circuit modelling of a RTS can be derived and implemented in the time and frequency domains.…”

Localización de faltas a tierra en sistemas de electrificación ferroviaria para alta velocidad, alimentados en 2×25 kV (sistema bifásico con autotransformadores)

“…Este sistema permite suministrar, sin incrementar la sección de la catenaria ni disminuir la distancia entre subestaciones, la elevada potencia, superior a 8 MW, demandada por un tren que circula a más de 300 km/h. Dentro de los sistemas de tracción con conductor negativo y autotransformadores, aunque también hay líneas con este sistema de tracción que utilizan otras tensiones como es el caso del ferrocarril del sureste de Pensilvania en Estados Unidos (12 kV+24 kV) [Natarajan y otros, 1997], el más utilizado es el sistema denominado 2×25 kV. La razón de denominarle de esta manera es porque entre el conductor positivo ó catenaria, y el carril hay una tensión de 25 kV de corriente alterna, y entre el carril y el alimentador negativo también hay una tensión de 25 kV de corriente alterna con polaridad contraria.…”