AS NZS IEC 60947.7.3:2015 pdf free download – Low-voltage switchgear and controlgear
8.5.2.7 Test procedure
The dummy fuse-links provided for the test (separate arrangement and compound arrangement) shall be selected from Table 2 and inserted into the fuse terminal block. The currents for the fuse terminal blocks being tested shall be so adjusted that the given maximum power dissipation values P V1 and/or P V2 , according to Table 2, are reached in conformity with the test arrangement of 8.5.2.2 and 8.5.2.3. The rated values shall remain constant during the whole testing duration. The test shall be continued until the temperature balance is reached. The temperature balance is reached when three successive readings, which shall be made at an interval of at least 5 min, do not show any further temperature rise. The measured results, determined at ambient temperature, shall be rectified to a reference temperature of 23 °C by means of a derating curve corresponding to the example shown in Annex B.
8.5.3 Durability
Fuse terminal blocks shall be resistant to heat and mechanical stresses which are liable to occur in normal use. Moreover, the requirements of 8.5.2 shall be taken into consideration. Compliance with these requirements is checked by the following test.
The fuse terminal block shall be subjected to the test for separate arrangement according to 8.5.2.2.1 or 8.5.2.3.1 , as applicable. The rated current related to the corresponding dummy fuse-link according to Table 2 shall be passed through the test arrangement (see examples below). The test shall be carried out continuously over a period of 1 68 h.
EXAMPLE 1 For an overload and short-circuit protection P V declared 2,5 W, 5 mm × 20 mm fuse-link: use a dummy fuse-link with 6,3 A and a power dissipation of 2,5 W.
EXAMPLE 2 For an exclusively short-circuit protection P VK declared 2,5 W, 5 mm × 20 mm fuse-link: use a dummy fuse-link with 6,3 A and a power dissipation of 1 W.
After the test, the fuse terminal block shall show no changes impairing its function as in normal use. The following requirements shall be met:
− dielectric tests according to 8.4.3;
− contact resistance test according to 8.4.4; the mean value shall not exceed 1 0 mΩ and the value of an individual measurement shall not exceed 1 5 mΩ;
− compatibility test between fuse terminal block and fuse-link according to 8.3.4.
8.5.4 Needle flame test
The test is carried out according to IEC 60695-1 1 -5 successively in the area of the fuse-link of three fuse terminal blocks. The test room shall be substantially draught-free with dimensions sufficient to ensure an adequate supply of air. Before the test, the fuse terminal blocks are stored for 24 h in an atmosphere having a tem- perature between 1 5 °C and 35 °C and a relative humidity between 45 % and 75 %. After this preconditioning, the fuse terminal block is mounted on its appropriate support and fixed with suitable means so that one lateral insulation wall lies parallel to the layer placed below it (see Figure 5).