Scientific paper ID 2069 : 2021/1

In recent years in the network of the National Railway Infrastructure Company, optical cables are gradually replacing the copper communication cable used for the transmission medium (telecommunication cable network). However, conventional interlocking systems are designed to work with copper cables. This s the modernization of conventional interlocking systems for using a communication channel. Promising solution to this problem is the use of safety technologies from industrial automation. Industry-leading safety technologies and PLCs are affordable and applicable for upgrading conventional interlocking systems. A number of companies has confirmed this worldwide. Suitable for this is Phoenix Contact`s SafetyBridge technology, which combines a safety programmable logic controller PLC and standard Ethernet network communication. Now, NRIC has two technical solutions for specific applications. These are specific developments from Bulgarian manufacturers specifically designed for the application. The implementation of SafetyBridge technology has its price, which is higher than that of specific developments. From a safety point of view, the high cost is fully justified by SIL3 certificates. The introduction of modern technology from the industry to NRIC is inevitable, but there is a slowdown due to the existing conservatism.