IEC 61977 pdf download

IEC 61977 pdf download Fibre optic filters – Generic specification
4.1.6 Normative reference extensions
Normative reference extensions are used to identify independent standards specifications orother reference documents integrated into blank detail specifications.
Unless a specified exception is noted,additional requirements imposed by an extension aremandatory. Usage is primarily intended to merge associated components to form hybriddevices,or integrated functional application requirements that are dependent on technicalexpertise other than fibre optics.
Published reference documents produced by the International Telecommunication Union(ITU), consistent with the scope statements of the relevant lEC specification series may beused as an extension. Published documents produced by other regional standardisationbodies such as the Telecommunications Industry Association (TIA), the EuropeanTelecommunications Standards Institute (ETSI), Japanese Industrial Standards (JIS) etc,maybe referenced in a bibliography attached to the generic.
Some optical fibre filter configurations require special qualification provisions which shall not beimposed universally.This accommodates individual component design configurations,specialisedfield tooling，or specific application processes. In this case requirements are necessary toguarantee repeatable performance or adequate safety, and provide additional guidance forcomplete product specification.These extensions are mandatory whenever used to prepare,assemble or install an optical fibre splice either for field application usage or preparation ofqualification test specimens.The relevant specification shall clarify all stipulations.However,design and style dependent extensions shall not be imposed universally.
ln the event of conflicting requirements，precedence， in descending order, shall be genericover mandatory extension, over blank detail, over detail, over application specific extension.
The following is an example of an optical connector extension:
. Using lEC 61754-4 and IEC 61754-2 to partially define a future IEC 60874-XXspecification for a duplex type “SC/BFOC/2,5” hybrid connector adapter.
Some commercial or residential building applications may require direct reference to specificsafety codes and regulations or incorporate other specific material flammability or toxicityrequirements for specialised locations.
Specialised field tooling may require an extension to implement specific ocular safety，elec-trical shock or burn hazard avoidance requirements, or require isolation procedures to preventpotential ignition of combustible gases.
4.2Documentation
4.2.1Symbols
Graphical and letter symbols shall, whenever possible, be taken from IEC 60027,IEC 60617and IEC 61748 unless superseded by this specification.