IEC 60811-403 pdf download

IEC 60811-403 pdf download.Electric and optical fibre cables – Test methods for non-metallic materials
4 Test method
4.1 General This part of IEC 6081 1 shall be used in conjunction with IEC 6081 1 -1 00. WARNING Attention is drawn to the toxicity of ozone. Precautions should be taken to minimize exposure of personnel to it at all times and the concentration in the workroom environment should not be allowed to exceed 1 ×1 0 -5 % by volume, or the value in the current industrial hygienic standard, whichever is the lower. Unless otherwise specified, tests shall be carried out at room temperature. 4.2 Apparatus The following apparatus shall be used: a) a device for generating a controlled amount of ozone; b) a means for circulating ozonized air under controlled conditions of humidity and temperature through a chamber containing the test pieces to be tested; c) a means for determination of ozone concentration; d) a suitable device for the clamping and elongation of test pieces; e) cylindrical mandrels consisting of wood or metal;f) a desiccator filled with silica gel or equivalent material; g) an accurate laboratory balance reading to 0,1 mg. 4.3 Pre-conditioning of the samples All the tests shall be carried out not less than 1 6 h after the extrusion or cross-linking, if any, of the insulating or sheathing compounds. If the test is carried out at ambient temperature, the test pieces shall be kept for at least 3 h at a temperature of (23 ± 5) °C. 4.4 Sampling and preparation of test pieces 4.4.1 Sampling of insulation Whether the cable is single or multicore, only one core needs to be tested. Sufficient length of core shall be cut from a position not less than 1 ,5 m from the end of the length of cable to provide two test pieces, unless the core has an extruded semi-conductor layer on the outside, in which case sufficient length for four test pieces shall be taken. Any sample that shows signs of mechanical damage shall not be used for the tests. 4.4.2 Sampling of sheath One sample of the cable or cord to be tested, or of the sheath removed from the cable, shall be taken of sufficient size to provide a minimum of two test pieces. Any sample that shows signs of mechanical damage shall not be used for the tests. 4.4.3 Preparation of test pieces from insulation Any protective coverings present on the core shall be removed without damaging the insulation, unless they were applied directly to the insulation prior to vulcanization and are adherent to it. If the core has a semi-conducting layer in the form of tape on the outside, this shall be removed. If the core has an extruded semi-conducting screen on the outside, this shall be removed from two test pieces and left in position on the other two.4.4.4 Preparation of test pieces from sheath Two dumb-bell test pieces shall be prepared in accordance with IEC 6081 1 -501 . The minimum test piece thickness shall be 0,6 mm. In the case of cables of such small size that it is not possible to prepare dumb-bell test pieces, the test method used shall be that specified for insulation. 4.5 Conditioning and deformation procedure of test pieces 4.5.1 Test pieces of insulation If the core does not have an extruded semi-conducting screen, one test piece shall be bent in the direction and plane of its existing curvature, without twisting, for one complete turn around a mandrel, and bound with twine or tape where the ends cross, and a second test piece of the same core shall be bent similarly in the plane of its existing curvature but in the opposite direction.