【正文】 of methods for the determination of safety integrity levels IEC 615086:—, Functional safety of electrical/electronical/programmable electronic safety related systems – Part 6: Guidelines on the application of IEC 615082 and IEC 615083 1) IEC 615087:—, Functional safety of electrical/electronical/programmable electronic safety related systems – Part 7: Overview of techniques and measures 1) IEC Guide 104:1997, The preparation of safety publications and the use of basic safety publications and group safety publications ISO/IEC 238214:1998, Data processing – Vocabulary – Part 14: Reliability, maintainability and availability ISO/IEC Guide 51:1990, Safety aspects – Guidelines for their inclusion in standards ISO 8402:1994, Quality management and quality assurance – Vocabulary ________ 1 ) To be published. Page 10 EN 61508?4:2020 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:24:19 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 3 Definitions and abbreviations For the purposes of this International Standard, the following definitions and the abbreviations given in table 1 apply. Table 1 — Abbreviations used in this standard Abbreviation Full expression Definition and/or explanation of term MooN MooND ALARP E/E/PE E/E/PES EUC PES PLC SIL M out of N channel architecture (for example 1oo2 is 1 out of 2 architecture, where either of the two channels can perform the safety function) M out of N channel architecture with diagnostics As low as is reasonably practicable Electrical/electronic/programmable electronic Electrical/electronic/programmable electronic system Equipment under control Programmable electronic system Programmable logic controller Safety integrity level Annex B of IEC 615086 Annex B of IEC 615086 Annex B of IEC 615085 Annex E of IEC 615086 Safety terms harm physical injury or damage to the health of people either directly or indirectly as a result of damage to property or to the environment [ISO/IEC Guide 51:1990 (modified)] NOTE – This definition will need to be addressed when carrying out a hazard and risk analysis (see IEC 615081, ). If the scope is to be widened ( to include environm ental dam age which may not give rise to physical injury or dam age to health) then this would need to be addressed in the Overall Scope Definition phase (see IEC 615081, ). hazard potential source of harm [Guide 51 ISO/IEC:1990] NOTE – The term includes danger to persons arising within a short time scale (for example, fire and explosion) and also those that have a longterm effect on a person’s health (for example, release of a toxic substance). hazardous situation circumstance in which a person is exposed to hazard(s) hazardous event hazardous situation which results in harm risk bination of the probability of occurrence of harm and the severity of that harm [ISO/IEC Guide 51:1990 (modified)] NOTE – For more discussion on this concept see annex A of IEC 615085. tolerable risk risk which is accepted in a given context based on the current values of society NOTE – See annex B of IEC 615085. Page 11 EN 61508?4:2020 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:24:19 GMT+00:00 2007, Uncontrolled Copy, (c) BSI residual risk risk remaining after protective measures have been taken safety freedom from unacceptable risk functional safety part of the overall safety relating to the EUC and the EUC control system which depends on the correct functioning of the E/E/PE safetyrelated systems, other technology safetyrelated systems and external risk reduction facilities safe state state of the EUC when safety is achieved NOTE – In going from a potentially hazardous condition to the final safe state, the EUC may have to go through a number of intermediate safe states. For some situations a safe state exists only so long as the EUC is continuously controlled. Such continuous control may be for a short or an indefinite period of time. reasonably foreseeable misuse use of a product, process or service under conditions or for purposes not intended by the supplier, but which can happen, induced by the product, process or service in bination with, or as a result of, mon human behaviour Equipment and devices functional unit entity of hardware or software, or both, capable of acplishing a specified purpose NOTE – In IEV 1910101 the more general term ―item‖ is used in place of functional unit. An item may sometimes include people. [ISO/IEC 2382140101] software intellectual creation prising the programs, procedures, data, rules and any associated documentation pertaining to the operation of a data processing system NOTE 1 – Software is independent of the medium on which it is recorded. NOTE 2 – This definition without note 1 differs from ISO 23821, and the full definition differs from ISO 90003, by the addition of the word data. equipment under control (EUC) equipment, machinery, apparatus or plant used for manufacturing, process, transportation, medical or other activities NOTE – The EUC control system is separate and distinct from the EUC. Page 12 EN 61508?4:2020 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:24:19 GMT+00:0