Protected Approaches to Power Supply Inputs of Railway Automation and Remote control Devices under Lightning Strikes

the article addresses the protection of power supply inputs of railway automation and remote-control devices against lightning overvoltages propagating along 10 kV overhead autoblocking lines. It is shown that during direct and repeated lightning strikes, the surge arrester installed directly at the protected facility may be subjected to unacceptable current and energy loads, which reduces the stability of the protection system. To investigate these processes, an integrated mathematical model of the system “overhead line – power supply input – protective devices” has been developed, including a threephase distributed-parameter line model, a lightning impact source based on the Heidler function, a relay cabinet power supply input model, a frequency-dependent grounding system model, and nonlinear models of surge arresters and multi-chamber arresters. The numerical implementation of the model was carried out in MATLAB. Computational experiments were performed for single and multiple lightning strikes under various protected-approach configurations and different arrangements of protective devices along the line. It was found that the uniform installation of surge arresters along the line does not provide the required stability under high-energy 10/350 μs impulses due to the exceedance of the permissible energy load of the devices. It is shown that the use of multi-chamber arresters makes it possible to significantly reduce the voltage at the power supply input and the load on the input surge arrester. The results obtained confirm the promise of spatially organized protection schemes that provide step-by-step limitation of the lightning wave and redistribution of impulse energy among several devices under single and multiple lightning strikes.