Trackside power distribution systems

A trackside power distribution system, comprising:

• a) a first signal supply unit having an input for receiving power from a first electrical power source, and an output for supplying power;
• b) a first feeder portion connected to the output of the first signal supply unit and extending alongside a track to a unit requiring power;
• c) a second signal supply unit having an input for receiving power from a second electrical power source, and an output for supplying power;
• d) a second feeder portion connected to the output of the second signal supply unit and extending alongside the track to said unit requiring power;
• e) a selection apparatus for selecting which feeder portion is used for supplying power to said unit requiring power, the selection apparatus being operative for isolating the output of at least one of the signal supply units from its respective feeder portion, the selection apparatus including switching means for alternatively connecting said unit requiring power to the first feeder portion, and for isolating said unit from the second feeder portion when in a first position, and for connecting said unit to the second feeder portion, and for isolating said unit from the first feeder portion when in a second position, the selection apparatus being operative for changing the position of the switching means automatically in response to one of a measurement of voltage at the feeder portions and a signal issued from at least one of the signal supply units;
• f) an enclosure in which the switching means is located;
• and
• g) at least one isolating transformer provided for electrical connection between the feeder portions and the switching means, the at least one isolating transformer being located outside the enclosure.

A trackside power distribution system, comprising:

• a) a first signal supply unit having an input for receiving power from a first electrical power source, and an output for supplying power;
• b) a first feeder portion connected to the output of the first signal supply unit and extending alongside a track to a unit requiring power;
• c) a second signal supply unit having an input for receiving power from a second electrical power source, and an output for supplying power;
• d) a second feeder portion connected to the output of the second signal supply unit and extending alongside the track to said unit requiring power;
• and
• e) a selection apparatus for selecting which feeder portion is used for supplying power to said unit requiring power, the selection apparatus being operative for selecting which feeder portion is used for supplying power to a load, and the selection apparatus further including a voltage slew rate limiter for limiting a rate of change of output voltage supplied to the load to below a threshold value.

A trackside power distribution system, comprising:

• a) a first signal supply unit having an input for receiving power from a first electrical power source, and an output for supplying power;
• b) a first feeder portion connected to the output of the first signal supply unit and extending alongside a track to a unit requiring power;
• c) a second signal supply unit having an input for receiving power from a second electrical power source, and an output for supplying power;
• d) a second feeder portion connected to the output of the second signal supply unit and extending alongside the track to said unit requiring power;
• e) a selection apparatus for selecting which feeder portion is used for supplying power to said unit requiring power;
• and
• f) at least one of the feeder portions comprising a cable comprising at least two discrete conductors, one of the conductors being arranged concentrically around the other of the conductors with an insulating sheath provided between the two cables.

A trackside power distribution system, comprising:

• a) a first signal supply unit having an input for receiving power from a first electrical power source, and an output for supplying power;
• b) a first feeder portion connected to the output of the first signal supply unit and extending alongside a track to a unit requiring power;
• c) a second signal supply unit having an input for receiving power from a second electrical power source, and an output for supplying power;
• d) a second feeder portion connected to the output of the second signal supply unit and extending alongside the track to said unit requiring power;
• e) a selection apparatus for selecting which feeder portion is used for supplying power to said unit requiring power;
• and
• f) at least one of the feeder portions decreasing in cross-sectional area along its length from an end nearest the respective signal supply unit to another end as a function of a current that the respective signal supply unit carries in operation.

A trackside radial power distribution system, comprising:

• a) first and second electrical power sources;
• b) at least one trackside unit requiring electrical power for its operation;
• c) a first signal supply unit having an input for receiving power from the first electrical power source, and an output for supplying power;
• d) a first feeder portion connected to the output of the first signal supply unit and extending alongside a track to the at least one trackside unit;
• e) a second signal supply unit having an input for receiving power from the second electrical power source, and an output for supplying power;
• f) a second feeder portion connected to the output of the second signal supply unit and extending alongside the track to the at least one trackside unit;
• and
• g) a selection apparatus associated with the at least one trackside unit for selectively drawing power from either feeder portion to supply power to the at least one trackside unit.