This Forum is aimed to support Power Distribution Professionals, involved in design or implementation of Power Distribution. It deals with Connectivity (Design, Select, Install, Commision & Operate, as well as Plug & Play Power Connectivity)
Circuits of ASSEMBLIES which are exempted from the verification of the short-circuit withstand strength
Could you please indicate in what cases circuits of Assemblies are exempted from the verification of the short-circuit withstand strength according to IEC 61439-1 and how we can apply this rule with limitor circuit-breaker ?
Re: Circuits of ASSEMBLIES which are exempted from the verification of the short-circuit withstand strength
The Clause 10.11.2 of IEC 61439-1 exempt from doing a short circuit test in two cases:
10.11.2 Circuits of ASSEMBLIES which are exempted from the verification of the short-circuit withstand strength
A verification of the short-circuit withstand strength is not required for the following:
1) ASSEMBLIES having a rated short-time withstand current (see 5.3.5) or rated conditional short-circuit current (see 5.3.6) not exceeding 10 kA r.m.s.
2) ASSEMBLIES protected by current-limiting devices having a cut-off current not exceeding 17 kA at the maximum allowable prospective short-circuit current at the terminals of the incoming circuit of the ASSEMBLY.
According to the second bullet, it’s possible to use the limitation characteristics of compact NSX & NSXm to avoid a short-circuit test for prospective short-circuit current that will be limited below 17kApeak
So the following values can be keep as a rule:
Maximum presumed short-circuit current in kArms where IEC 61439 sort-circuit withstand test is not required
(Clause 10.11.2 -2) with specified incomer : 415Vac 50Hz