IEC 60664-3:2003

Insulation coordination for equipment within low-voltage systems - Part 3: Use of coating, potting or moulding for protection against pollution

Applies to assemblies protected against pollution by the use of coating, potting or moulding, thus allowing a reduction of clearance and creepage distances as described in Part 1 or Part 5. This standard describes the requirements and test procedures for two methods of protection: - type 1 protection improves the microenvironment of the parts under the protection; - type 2 protection is considered to be similar to solid insulation. This standard also applies to all kinds of protected printed boards, including the surface of inner layers of multi-layer boards, substrates and similarly protected assemblies. In the case of multi-layer printed boards, the distances through an inner layer are covered by the requirements for solid insulation in Part 1. This standard refers only to permanent protection. It does not cover assemblies that are subjected to mechanical adjustment or repair. The principles of this standard are applicable to functional, basic, supplementary and reinforced insulation. Has the status of a basic safety publication in accirdance with IEC Guide 104. The major changes made during the revision of IEC 60664-3 were the following: - Part 3 has been exactly aligned with Part 1 (including amendments 1 and 2). It has been made clear that Part 3 can only be used as a whole document together with Part 1 of IEC 60664. - The scope of Part 3 has been greatly extended including now also potting and moulding and similar procedures providing protection against pollution. The standard also applies to all kinds of coated printed boards including the surface of inner-layers of multi-layer boards, substrates and similar protected assemblies. The distances through an inner layer of multi-layer boards however are covered by the requirements for solid insulation in Part 1. - The difference between the two types of protection has been clarified. Type 1 (formerly type A) protection leads to a reduction of the pollution degree present beyond the protection to pollution degree 1. Type 2 (formerly type B) protection introduces protection systems which can be considered similar to solid insulation. Consequently the dimensioning and test requirements have been aligned more correctly. - The area of application has been extended including now functional, basic, supplementary and reinforced insulation. - Type 1 and type 2 protection now can both be used under the conditions of pollution degree 3 (formerly only type B). - Not only type 2 protection but also type 1 protection requires that between two conductive parts 100 % of the distance across the spacing shall be covered by the protection. - For type 2 protection minimum distances have been introduced. In any case the spacings shall not be lower than the minimum value of 10 µm. - Also the new Part 5 of IEC 60664 is referred to. - The tests follow much more closely the different requirements for type 1 and type 2 protection. The protected assembly shall withstand the electrical tests for solid insulation in 4.1.2 of IEC 60664-1. For type 1 protection, the partial discharge test is not applicable. For type 2 protection, the partial discharge test is required. The required partial discharge extinction voltage and the test method are specified in 4.1.2.4 of IEC 60664-1. - The requirements for the test specimen have been aligned with the extended scope. - The tests for the "adhesion of coating" and the "scratch resistance test" have been updated.

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