IEC 61508-4 PDF

3 Dec IEC Standard | functional safety, smart city | Functional safety of electrical/electronic/programmable electronic safety-related. 12 May 4) In order to promote international unification, IEC national IEC has been prepared by sub-committee 65A: System aspects, of IEC. IEC contains the definitions and explanation of terms that are used in parts 1 to 7 of the IEC series of standards. The definitions are.

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If computer system technology is to be effectively and safely exploited, it is essential that those responsible for making decisions have 65108-4 guidance on the safety aspects on which to make those decisions. This does not preclude the free use, in course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations.

General requirements lEC International Standard lEC Guide NOTE 2 – The safety- related systems are designed to prevent the EUC from going into a dangerous state by taking appropriate action on receipt 6108-4 commands.

Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

Although there may be other systems having safety functions, it is the safety-related systems that have been designated to achieve, in their own right, the required tolerable risk Safety- related systems can broadly be divided into ied control systems and safety-related protection systems, ic have two modes of operation see 3.

Fundamental terms ISO See also annex A of lEC An example of such a fault is a design fault. This unified approach has been adopted in order that a 6508-4 and consistent technical policy be developed for all electrically baseo safety-related systems. The failure of a safety-related system would be included m the events leading to the determined hazard or hazards.


Certain conventions are, however, not identical to those used in Indian Standards. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. Overview of techniques oec measures ISO H c Single PES with dual program- mable electronic devices linked in a serial manner for example intelligent sensor and programmable controller H PEi d Single PES with dual program- mable electronic devices but with shared sensors and final elements i.

Review of Indian Standards Amendments are issued to standards as the need arises on the basis of comments. Dependability and quality of service lEC The corresponding Indian Standards, which are to be substituted in their respective places, are listed below along with their degree of equivalence for the editions 16508-4 That is, the required safety integrity level may be achieved by implementing the safety functions in the EUC control system and possibly by additional separate and independent systems as well or the safety functions may be implemented by oec and independent systems dedicated to safety NOTE 4 – A safety-related system may a be designed to prevent the hazardous event i.

Automatic control lEC Examples of methods for the determination of safety integrity jec lEC If separate channels are used, these tests are done for each channel separately.

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In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. For undated references, the latest edition of the normative document referred to applies. Data processing – Vocabulary – Part Search the history of over billion web pages on ied Internet. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision.

Any safety strategy must therefore consider not only all the elements 611508-4 an individual system for example sensors, controlling 6150-4 and actuators but also all the safety-related systems making up the total combination of safety-related systems.

EXAIWPLE Verification activities include – reviews on outputs documents from all phases of the safety lifecycle to ensure compliance with the objectives and requirements of the phase, taking into account the specific inputs to that phase; design reviews: The text of lEC Standard has been approved as suitable for publication as an Indian Standard without deviations.


International Standard lEC For dated references, subsequent amendments to, or revisions of, any of these publications do not apply However, parties to agreements based on this part of lEC are encouraged to investigate the possibility of applying the most recent editions of the normative 65108-4 indicated below.

65108-4 Users of Indian Standards should ascertain that they are in possession uec the latest amendments or edition by referring to the latest issue of ‘BIS Catalogue’ and ‘Standards: NOTE iev – The term safe diagnostic coverage, or diagnostic coverage including sate failures, is used to descnbe respectively the fractional decrease in the probability of safe hardware failure, or of both safe and dangerous hardware failures, resulting from the operation of the automatic diagnostic tests 3.

Figure 2 — Programniable electronic system PES: Programming languages I EC 61 The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. Attention is particularly drawn to the following: Copyright BIS has the copyright of all its publications. A major objective is to facilitate the development of application sector standards. This Indian Standard has been developed from Doc: Lec and abbreviations [ETD Computer-based systems genencally referred to as programmable electronic systems PESs are being used in all application sectors to perform non-safety functions and, increasingly, to perform safety functions.

In most situations, safety is achieved by a number of protective systems which rely on many technologies for example mechanical, hydraulic, pneumatic, electrical, electronic, programmable electronic.

Figure 4 – Failure model 3. NOTE 2 – The term can be used to describe a complete system, or a portion of a system for example, sensors or final elements. Figure 2 d illustrates a PES with dual programmable electronics i e two-channel but with a single sensor and a single actuator 3.

For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test, shall be rounded off in accordance with IS 2: