Design verification

Design verification is a prerequisite for all assemblies

provided. It is fundamental to ensuring every assembly

meets its defined design requirements. There is flexibility

in the way in which this is achieved within the new standard,

and some new concepts have been introduced, but the

options are defined and where necessary their use is

restricted and a design margin applied.

 

Examples of the limitations and margins applied to verification without type test include;

 All assemblies connected to a supply with a prospective short circuit current in excess of 10kA

 rms or having a cut-off current of 17kA peak must be of a type-tested design or the verification

 must be an interpolation from a reference design. Under no circumstances can the assigned

 short circuit current rating be higher than that of the reference design.

 So as to take account of the air temperature within the enclosure, thermal interactions and

 possible hot spots; components within a circuit that has not been temperature rise tested,

 must be de-rated to 80% of their free air current rating.

 Comparison of the power loss of the components within an assembly with the known heat

 dissipation capability of an enclosure, is restricted to assemblies having a rating of 630A.

 Confirmation of temperature rise performance by calculation is limited to assemblies with a

 rating not exceeding 1600A. Test or interpolation from a tested design must be used to verify

 higher ratings.