This paper focuses on transits available around the world. AC voltage transits and DC voltage transit are reviewed and compared. Emphasis is given to differences, advantages and disadvantages of voltage supplies and traction types. First, differences between bus rapid transit (BRT), metro, light rail transit (LRT) and light metro are covered, with special attention to statistical of annual passengers per year, an attribute that defines the type of railway transit. Mention is also made to the history of DC and AC overhead wires, other traction preferences for metro transit and highlighted differences between the third rail and fourth rail traction. Malaysian transit systems are then discussed, with special attention to LRT Kelana Jaya line, world"s third DC transit that employs the fourth rail traction. The discussion have produced relevant statistical data that this paper is in part aimed at summarizing and at comparing with what accomplished on the same subject within the third rail traction framework. The increased in LRT Kelana Jaya line annual passengers per year is a proof of success for the fourth rail technology.
This paper presents a study on the performance of a fourth rail direct current (DC) urban transit affected by an indirect lightning strike. The indirect lightning strike was replicated and represented by a lightning-induced overvoltage by means of the Rusck model, with the sum of two Heidler functions as its lightning channel base current input, on a perfect conducting ground. This study aims to determine whether an indirect lightning strike has any influence with regard to the performance of the LRT Kelana Jaya line, a fourth rail DC urban transit station arrester. The simulations were carried out using the Electromagnetic Transients Program–Restructured Version (EMTP–RV), which includes the comparison performance results between the 3EB4-010 arrester and PDTA09 arrester when induced by a 90 kA (9/200 µs). The results demonstrated that the PDTA09 arrester showed better coordination with the insulated rail bracket of the fourth rail. It allowed a lower residual voltage and a more dynamic response, eventually resulting in better voltage gradient in the pre-breakdown region and decreased residual voltage ratio in the high current region.
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