IEC 60811-202:2017 pdf download

IEC 60811-202:2017 pdf download.Electric and optical fibre cables – Test methods for non-metallic materials
1 Scope
This Part 202 of IEC 6081 1 gives the methods for measuring thicknesses of non-metallic sheath which apply to the most common types of sheathing compounds (cross-linked, PVC, PE, PP, etc.).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 6081 1 -1 00:201 2, Electric and optical fibre cables – Test methods for non-metallic materials – Part 100: General
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 6081 1 -1 00 apply.
4 Test method
4.1 General This part of IEC 6081 1 shall be used in conjunction with IEC 6081 1 -1 00. Unless otherwise specified, tests shall be carried out at room temperature. The measurement of sheath thickness may be required as an individual test, or as a step in the procedure for carrying out other tests, such as the measurement of mechanical properties. The test method applies to the measurement of all sheaths for which thickness limits are specified, for example separation sheaths, as well as external sheaths. In each case, the method of selecting samples shall be in accordance with the relevant cable standard.
4.2 Measuring equipment A measuring microscope or a profile projector of at least 1 0 x magnification or an optical digital image analyser shall be used. All These types of equipment shall allow a reading of 0,01 mm and an estimated reading to three decimal places when measuring insulation with a specified thickness less than 0,5 mm. For sheaths applied over longitudinally irregular surfaces such as corrugated metallic sheaths, a micrometer having a ball nose radius of 1 mm and allowing a reading of 0,01 mm
4.3 Sample and test piece preparation 4.3.1 Sheaths applied over longitudinally regular surfaces After all materials, if any, inside and outside the sheath have been removed, each test piece shall be prepared by cutting a thin slice along a plane perpendicular to the longitudinal axis of the cable, using a suitable device. If the sheath carries an indenting marking, thus giving rise to a local reduction in thickness, the test piece shall include such marking. 4.3.2 Sheaths applied over longitudinally irregular surfaces Cut a short piece of sheath, perpendicular to the longitudinal axis of the cable, including at least one complete pitch or helix formed by the underlying tape. If using a ball nose micrometer, the sample may be left whole. If using a microscope or profile projector, the test piece shall be prepared by cutting six thin longitudinal slices (parallel to the cable axis), using a suitable device. 4.3.3 Sheath applied over corrugated metallic sheaths A sample of complete cable shall be taken, 500 mm from the end of the drum and of sufficient length to include two peaks and two troughs. A reference line shall be drawn on the outer surface of the over sheath, parallel to the axis of the cable. The position of the minimum thickness shall be determined on an annular ring taken from the end of the sample. A strip shall then be cut at this minimum point parallel to the axis of the cable (the previously drawn reference line shall be used to locate this position).
4.4 Measuring procedure The test piece shall be placed under the measuring equipment with the plane of the cut perpendicular to the optical axis. a) When the inner profile of the test piece is of circular form, six measurements shall be made radially, each approximately 60°, as shown in Figure 1 . b) If the substantially circular inner surface is not regular or smooth, six measurements shall be made radially at the positions where the sheath is thinnest, as shown in Figure 2. c) When the inner profile exhibits deep grooves caused by the cores, radial measurements shall be taken at the bottom of each groove, as shown in Figure 3. When the number of grooves exceeds six, item b) applies. d) In order to eliminate the influence of any irregularities on the outer surface, which may be due to the presence of a proofed tape or a ribbed sheath finish, the measurements shall be made as shown in Figure 4.