The article presents issues regarding the impact of operating conditions on the functional reliability of representative fire alarm systems (FASs) in selected critical infrastructure buildings (CIB). FAS should operate correctly under variable environmental conditions. FASs ensure the safety of people and CIB. Operational measurements for 10 representative systems were conducted in order to determine the impact of environmental conditions on FAS reliability. Selected operational indices were also determined. The next stage involved developing two models of representative FASs and the availability, pre-ageing time and operating process security indices. Determining operational indices is a rational selection of FAS technical and organizational solutions that enables the reliability level to be increased. Identifying the course of the FAS operating process security hazard changes in individual system lines, particularly at the initial operation stage, enables people that supervise the operation to affect operating parameters on an ongoing basis. The article is structured in the following order: issue analysis, FAS power supply in CIB, operational test results, selected FAS operating process models, determination of operational and security indices, and conclusions.

The article presents a general method for identity the security risk factor for alarm signal transmission systems (ASTS), which are used in monitoring buildings and critical infrastructure. The security of the transmission of alarm signals to an alarm receiving center (ARC) is a property of the process, which is associated witch performing of tasks and functions, human factor, hardware and environment components. The process of transmitting alarm signals should be characterized by minimizing risk of external and internal interception/distortion or deformation of transmitted signals and in ideal case signals should be encrypted and integrity checked. Determining the security risk indicator for ASTS will allow optimal organization of electronic security systems.

This article discusses issues regarding electromagnetic interference generated unintentionally by transport telematics systems and electronic security systems (ESS) located within a railway area. These systems should operate correctly, since they ensure the safety of both vehicles and passengers. The electronic devices they use are exposed to electromagnetic interference that may lead to incorrect ESS functioning. In order to determine the impact of electromagnetic interference on ESS, the authors measured unintentional low-frequency electromagnetic field generated by MV—15 and 30 kV—power lines. This enabled determining the areas with maximum values of electromagnetic interference. The next stage of the research was to develop an ESS operating process model that takes into account the impact of unintentionally generated electromagnetic interference on the operating process. Introducing the electromagnetic interference impact coefficient enables a rational selection of solutions aimed at protecting against electromagnetic interference through the application of technical and organizational measures.

The article presents issues related to the use of electronic security systems (ESB) on a vast railway area. These systems are operated in very different environmental conditions. Due to the fact that electrical and electronic systems coexist on the extensive railway area for various purposes - e.g. power supply systems for railway traction, rail traffic control systems (SRK), electronic security systems - fire alarm system (SSP), CCTV system (CCTV), access control system (SKD), a significant operational problem in addition to environmental changes in which the above-mentioned technical facilities are used, there is also the issue of electromagnetic compatibility. Depending on the area extent of the railway area, construction, technical configuration, way of alarming, safety classes of these systems may be different. In SSP there is another factor that affects the configuration of these systems, namely the so-called fire scenario and how to notify the State Fire Service (PSP) about an existing fire risk or damage. There are several different ESB structures - focused, distributed and mixed. The type of ESB used in a given railway facility - construction or open area is conditioned by its cubic capacity [m3], terrain extent [m2 or km2] and the number of supervised facilities. The use of a given type of ESB to ensure safety and fire protection in a given railway area also depends on the requirements of legal provisions for the object(s), the fire scenario that must be implemented by the system, legal requirements for the given protected area, the accepted scope of protection and the reliability and operational requirements to be met by these installations. The article presents basic issues related to ESB operation that are used in the selected railway area. The review of technical solutions of selected ESBs and the methodology of conducting the analysis for the purposes of developing, e.g. fire scenario or hazard analysis, presented in the article, will enable railway facility designers to properly develop design assumptions.

A fire alarm system (FAS) is one of the most important safety facilities used in any building, and include CCTV and intrusion and panic alarms. Pursuant to the Polish Regulation of the Minister of the Interior and Administration of 07/06/2010, FASs are required in specific civil structures. FASs are directly responsible for the protection of the life and health of humans and animals, and indi-rectly for property at the protected sites. In considering the fire hazards and scenarios, a FAS should be characterized with sufficient reliability. Every FAS is subject to specific requirements in terms of reliability and continuity of performance at the stages of monitoring, FAS failure, and fire. This work is an analysis of the reliability requirements for FAS. Keywords: fire alarm system, reliability requirements, structures.