Functional safety of traction railway rolling stock

The article describes approaches to the definition of functional safety in railway transport. The importance of compliance with requirements for functional safety in the context of widespread use of programmable controllers and microprocessor control systems is shown. Electric locomotive is considered from the point of functional safety, as well as its structural scheme which is used to carry out necessary checks. Main sources of threats for railway rolling stock were described, which include the malfunction of some component parts of the electric locomotive and external influences, including erroneous actions of locomotive crew. This article discusses the concept of risk of breaching safety requirements as well as demonstrates approach for assessing the level of risk, which involves quantitative and qualitative assessment of the probability and consequences of risk. Necessity of considering potential damage to human health, environmental damage and financial losses when performing risk assessment is shown. The article shows the necessity of determining safety features of railway rolling stock targeted to counteraction to external and internal threats. Methods of determining safety integrity levels for the various safety functions is demonstrated on the base of using risk graph, which takes into account the probability of a hazardous event and damage caused to them. Necessity of using different devices to achieve required safety integrity level is shown. Method for determining the actual safety integrity level of the safety contour based on the use of the “graph of safety” is shown and includes analysis of devices in this contour. This method allows determining the safety integrity level of the safety contour rolling stock on the basis of experience in the production and usage of devices of control and diagnosis. An example of compliance one of the safety functions of the electric locomotive to the requirements of functional safety is closely considered in the article. In the example is shown, what measures are possible to apply to increase the functional safety of the electric locomotive to meet the requirements for safety integrity level.

functional safety, safety integrity level (SIL), risk assessment, safety function, microprocessor systems

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