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Which are the temperature limits during the abnormal operating conditions?

More specifically you asked, which are the temperature limits during the abnormal operating conditions? In 5.4.1.4.3 of IEC 62368-1 there are the temperature limits during the normal operating conditions (see Table 10) but we can't find the temperature limits during the abnormal operating conditions, in particular for electronic component and insulating materials. In IEC 60065 there is Table 3 "Permissible temperature rise of parts of the apparatus" which is very clear and there are 2 columns, one for "Normal operating conditions" and another one for "Fault conditions". In B.4.8 of IEC 62368-1 there is the requirement: "During and after single fault conditions, any flame inside the equipment shall extinguish within 10 s and no surrounding parts shall have ignited". It seems that there is no temperature limit: can you confirm?

 

In response, in 62368-1 2ndEd (and 3rdEd) temperature limits under abnormal conditions depend on the energy source being classified i.e. Clause 9 - Thermal burn injury; and for components that function as component safeguards.  

 

In IEC 60065 8thEd, all temperature limits were documented primarily in Table 3.  In IEC 62368-1 (3rdEd), temperature limits are associated with the energy source and a component when it functions as a component safeguard. 

 

For touch temperatures, classification is done considering normal, abnormal and single fault conditions. The TS classification (and its associated maximum temperature) depends on application, intended user and user access. 

 

For component safeguards, requirements for these components, devices and/or sub-assemblies, are detailed in the identified annexes/subclauses for the components e.g. Transformers, subclause G.5.3

 

In 62368-1 there is not a single location that specifies all maximum temperatures with their associated condition and component. Hazard based engineering was used to develop the requirements, so the applicable limits are associated with the energy source and/or application.

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