Nowadays one of the most popular and most important means of public transport is the railway. It is a cheap alternative of cargo transport as well.
The electrification of the railway system follows a wide variety of methods country by country, applying different voltage and frequency. In Hungary a single phase system are used, operating with a 25 kV voltage and 50 Hz frequency. The frequency of short circuits in the railway overhead network is ten times bigger than those in the three-phased electrical network. The present study aims to provide an overview about the Hungarian reclosing system and about the methods of detecting the short circuit without the risk of damage of the overhead network.
The first unit contains a brief historical overview of the railway’s electrification in Hungary from the first railroad to present times.
It is followed by the description of the testing resistor, its crucial role in the reclosing system, an introduction to the so-called MP system's functions and to reclosing system’s requirements as well. This is clearly not the only protection method applied in the railways’ system; there are several other techniques of such protection which are described in the third unit.
The testing resistors can be classified into three different groups accordingly their different physical characteristics, which are depicted in the forth unit. The closure of the present study contains a specific summary and evaluation of the characteristics of the reclosing systems applied in the Hungarian substations.