Iec Tr 61641.pdf
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Iec Tr 61641.pdf
What is IEC TR 61641 and why is it important for low-voltage switchgear and controlgear assemblies
IEC TR 61641 is a technical report that gives guidance on the method of testing of enclosed low-voltage switchgear and controlgear assemblies under conditions of arcing in air due to an internal fault[^1^]. The purpose of this test is to assess the ability of the assembly to limit the risk of personal injury, damage of assemblies and its suitability for further service as a result of an internal arcing fault[^2^].
IEC TR 61641 is important for low-voltage switchgear and controlgear assemblies because it provides a standardized way of evaluating their performance and safety under extreme conditions. Arcing faults can cause severe damage to the equipment and pose a serious threat to the operators and nearby personnel. By following the guidelines of IEC TR 61641, manufacturers and users can ensure that their assemblies meet the minimum requirements for protection against arcing faults and can select the appropriate level of protection according to the intended application and location of the assembly[^2^].
IEC TR 61641 defines three arcing classes to describe the different forms of protection provided against arcing faults[^2^]:
Class I: Personnel protection. The assembly prevents the escape of hot gases, flames or solid particles that could cause harm to persons in the vicinity.
Class II: Damage restricted to part of the assembly. The assembly limits the damage caused by the arcing fault to a defined area within the assembly and does not impair its overall functionality.
Class III: Assembly suitable for limited further service. The assembly contains the arcing fault within its enclosure but may suffer significant damage that requires repair or replacement before further use.
IEC TR 61641 also defines two levels of personnel protection afforded by assemblies under arcing fault conditions[^2^]:
Level A: For assemblies installed in areas where access to the assembly is restricted to skilled persons who are aware of the hazards and can take appropriate precautions.
Level B: For assemblies installed in areas where the area is accessible to ordinary persons who may not be aware of the hazards or able to take appropriate precautions.
The level of personnel protection is determined by the distance between the assembly and any possible position of a person during normal operation. Level A requires a minimum distance of 300 mm, while level B requires a minimum distance of 500 mm[^2^].
The test procedure described in IEC TR 61641 involves applying a short-circuit current to a specified point within the assembly and measuring the effects of the resulting arcing fault. The test parameters include the rated voltage, rated current, power factor, duration and frequency of the arcing fault. The test criteria include the absence of holes or openings in the enclosure, absence of ignition of indicators outside the enclosure, absence of projection of parts or fragments outside the enclosure, correct functioning of doors and covers after the test, correct functioning of indicators after the test, correct functioning of switching devices after the test, absence of damage to adjacent compartments or units within the assembly, and absence or extent of damage to internal components within the affected area[^2^].
IEC TR 61641 also provides guidance on how to label and mark assemblies that have been tested according to its recommendations. The label should indicate the class and level of protection, as well as the test parameters and criteria[^2^]. 061ffe29dd