IEC 62114 pdf download – Electrical insulation systems (EIS) — Thermal classification
1 scope
This International Standard establishes the thermal classification of an electrical insulationsystem (EIS). It also identifies recognized procedures for the thermal evaluation of EIS.
This standard is applicable to EIS used in electrotechnical devices where the thermal factor isthe dominating ageing factor.
2Normative references
The following normative documents contain provisions which，through reference in this text,constitute provisions of this International ‘Standard. For dated references,subsequentamendments to, or revisions of, any of these publications do not apply.However,parties toagreements based on this International Standard are encouraged to investigate the possibilityof applying the most recent editions of the normative documents indicated below. For undatedreferences，the latest edition of the normative document referred to applies.Members of lECand lso maintain registers of currently valid lnternational Standards.
IEC 60505,Evaluation and qualification of electrical insulation systems
IEC 61857 (all parts)，Electrical insulation systems – Procedures for thermal evaluation
IEC 61858,Electrical insulation systems – Thermal evaluation of modifications to anestablished wire-wound EIS
3 Definitions
For the purpose of this International Standard, the terms and definitions given in lEC 60505,as well as the following definition, apply:
3.1
thermal class
designation of an ElS that is equal to the numerical value of the maximum use temperature indegrees Celsius (C) for which the EIS is appropriate
4General considerations
4.1 Thermal evaluation of EIs
Experience has demonstrated that,under normal operating conditions, satisfactory economiclife is obtained for electrotechnical devices such as rotating machines,transformers,etc., thatare designed and built in accordance with standards based on thermal evaluations of EIS.
4.2Maximum use temperature
The thermal classes in this standard are numerically equal to the maximum use temperaturesrecommended for the EIS under normal operating conditions as defined by the producttechnical commititee.
Product TCs shall determine the operating conditions under which the maximum temperatureof the device may differ from the thermal class of the ElS.Such situations may occur becauseeither a shorter or longer life than normal is envisaged,or exceptional conditions of serviceexist.
4.3Relation of EIM to EIS
The description of an electrotechnical device as being of a particular thermal class does notmean,and must not be taken to imply that each EIMused in its construction is of the samethermal endurance.
The thermal class for an Els may not be directly related to the thermal endurance of theindividual EIM included in it. In the ElS,the protective character of other EIM used in thesystem may improve the thermal endurance of an individual EIM.On the other hand, problemsof incompatibility between EIM may decrease the appropriate thermal class of the systembelow the thermal endurance of the EIM.Such situations shall be investigated by the testprocedures referenced in clause 5.
NOTE Thermal endurance of ElNM is addressed in lEC 60216.
4.4other factors of influence
Apart from thermal factors，the ability of the ElS to fulfil its function is affected by manyfactors,such as electrical and mechanical stresses,vibration, deleterious atmospheres andchemicals，moisture, dirt and radiation.All such factors should be taken into account whendesigning particular electrotechnical devices, and further guidance on the evaluation of theseaspects may be found in lEC 60505.
4.5Performance factors
Actual performance of the device depends on the specific conditions of operation that mayoccur and which may vary widely，e.g. environmental exposure,duty cycles and type ofproduct.Further，the intended performance in service depends on the relative importance ofsize,reliability, desired period of use of associated equipment and/or economicconsiderations.
5Thermal evaluation of electrical insulation systems
Test procedures for the thermal evaluation of ElS shall follow the precepts set forth inIEc 60505.Specific test procedures for ElS are listed in annex A.
6Thermal classification of electrical insulation systems
Thermal classes shall be assigned to an EIS based on service experience or on the results offunctional tests based upon test procedures in accordance with clause 5.IEC 62114 pdf download – Electrical insulation systems (EIS) — Thermal classification
IEC 62114 pdf download – Electrical insulation systems (EIS) — Thermal classification
