Obecné elektrotechnické normy

Fault tree analysis (FTA) is used to identify and analyse combinations of events, conditions and factors that cause or can potentially cause or contribute to the occurrence of a defined undesirable outcome, referred to as the "top event". This document describes the (FTA) technique and provides guidance on its application. This includes:

definition and description of commonly used terms and symbols;

purpose, applications and limitations of FTs;

a description of basic concepts and principles;

a description of the steps involved in scoping, constructing and developing the FT;

guidance on performing qualitative and quantitative analysis of the FT, including discussion of requirements and limitations of the associated mathematical models;

identification of basic items that should be included when documenting and reporting the FTA;

methods for performing FTA when some of the commonly used assumptions are not satisfied (e.g., non-coherent FTs, dynamic FTs);

example applications in support of the above;

procedures for calculating dependability measures (unavailability, failure frequency and unreliability) for different types of system, with constant or time dependent probabilities or with non-repaired or repaired items).

In annexes, the document also describes:

the relationship of FTA with other related techniques such as Reliability Block Diagram analysis (IEC 61078), Failure Mode and Effects Analysis (FMEA) (IEC 60812), Event Tree Analysis (IEC 62502) and Markov techniques (IEC 61165);

methods by which the importance of various events included in the FT can be established;

automated fault tree construction;

mathematical models required for large and more complex FTs;

numerical examples demonstrating the use of FTs in dependability.

This International Standard establishes the detailed classification of the N family (insulating liquids) that belongs to class L (lubricants, industrial oils and related products) in accordance with ISO 8681 and ISO 6743-99, affecting product categories that include products derived from petroleum processing, synthetic chemical products and synthetic and natural esters.

This standard applies to unused liquids.  For liquids in service, additional testing may be required to ensure compliance with this standard.

This International Standard establishes the detailed classification of the N family (insulating liquids) that belongs to class L (lubricants, industrial oils and related products) in accordance with ISO 8681 and ISO 6743-99, affecting product categories that include products derived from petroleum processing, synthetic chemical products and synthetic and natural esters.

This standard applies to unused liquids.  For liquids in service, additional testing may be required to ensure compliance with this standard.

This International Standard introduces the concept to check the reliability and functionality of reused parts and their usage within new products. It also provides information and criteria about the assurance, for example, testing and analysis, required for products containing reused parts, which are declared "qualified-as-good-as-new" (QAGAN), relative to the designed life of the product.

This standard specifies requirements which shall be satisfied before making a declaration or applying a designation of QAGAN. The standard also gives guidance to support any organisation which makes declarations about dependability of products containing reused parts.

In this standard, the term "product" covers electrical, electro-mechanical, mechanical parts or hardware that may contain software. "Qualified-as-good-as-new" (QAGAN) does not apply to software products, concepts, and ideas.

This standard does not cover reused materials or large structures and large systems.

The purpose of this standard is to ensure by tests and analysis that the reliability and functionality of a new product containing reused parts is comparable to a product with only new parts. This would justify the manufacturer granting the next customer the full warranty of the product with "qualified-as-good-as-new" (QAGAN) parts.

NOTE This standard can also be applied in producing product specific standards by technical committees responsible for an application sector.

Annex A describes extending useful life by refurbishment, updating, upgrading, maintenance and used as second-hand. These concepts are defined and the requirements for using the term with reference to this standard are stated.