IEC 61439-2:2009 pdf download.Low-voltage switchgear and controlgear assemblies
8.2.101 Degree of protection of withdrawable parts
The degree of protection indicated for PSC-ASSEMBLIES normally applies to the connected position (see 3.2.3) of withdrawable parts. The ASSEMBLY manufacturer shall indicate the degree of protection obtained in the other positions and during the transfer between positions.
PSC-ASSEMBLIES with withdrawable parts may be so designed that the degree of protection applying to the connected position is also maintained in the test and isolated positions and during transfer from one position to another.
If, after the removal of a withdrawable part, the original degree of protection is not maintained,an agreement shall be reached between the ASSEMBLY manufacturer and user as to what measures shall be taken to ensure adequate protection. Information provided by the ASSEMBLY manufacturer may take the place of such an agreement.
8.3.2 Clearances
Addition: Where functional units are mounted on withdrawable parts, the isolation provided in the isolated position shall at least comply with the requirements in the relevant specification for disconnectors (see IEC 60947-3). This applies with the equipment in new condition, taking account of the manufacturing tolerances and anticipated changes in dimensions due to wear.
The isolating distance between the withdrawable unit main contacts and their associated fixed contacts in the isolated position shall be capable of withstanding the test voltage for the declared impulse withstand voltage as specified in Table 102.
Replacement of last paragraph:When removable or withdrawable parts are equipped with a metal supporting surface, these surfaces shall be considered sufficient for ensuring earth continuity of protective circuits provided that the pressure exerted on them is sufficiently high. The continuity of the protective circuit of a withdrawable part shall remain effective from the connected position to the isolated position inclusively.
8.5.2.101 General
The removable and withdrawable parts shall be so constructed that their electrical equipment can be safely isolated from or connected to the main circuit whilst this circuit is live. The removable and withdrawable parts may be provided with an insertion interlock (see 3.2.5 of Part 1). Minimum clearances and creepage distances (see 8.3 of Part 1 and 8.3.2 above) shall be complied with in the different positions as well as during transfer from one position to another.
NOTE It may be necessary to ensure that these operations are not performed under load.
8.5.2.103 Withdrawable parts
Withdrawable parts shall have in addition an isolated position (see 3.2.103) and may have a est position (see 3.2.102), or a test situation (see 3.1.102). They shall be distinctly located in these positions. These positions shall be clearly discernible.IEC 61439-2 pdf download.