IEC 60811-1-1:2001 pdf download

IEC 60811-1-1:2001 pdf download.Common test methods for insulating andsheathing materials of electric cablesand optical cables – Part 1-1:Methods for general application – Measurement of thickness and overall dimensions -Tests for determining the mechanical properties.
8 Measurement of thicknesses and overall dimensions
8.1 Measurement of insulation thickness
8.1.1 General
Measurement of insulation thickness may be required as an individual test, or as a step in the
procedure for carrying out other tests, such as the determination of mechanical properties. In each case, the methods of selection of samples shall be in accordance with the relevant cable standard.
8.1.2 Measuring equipment
A measuring microscope or a profile projector of at least 10 x magnification. Both 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.
In case of doubt, the measuring microscope shall be taken as the reference method.
8.1.3 Preparation of test pieces
Any covering shall be removed from the insulation, and the conductor(s), together with separator (if any) shall be withdrawn, care being taken to avoid damage to the insulation. Semi-conducting inner andlor outer layers, if bonded to the insulation, shall not be removed.
Each test piece shall consist of a thin slice of insulation. The slice shall be cut with a suitable device (sharp knife, razor blade. etc.) along a plane perpendicular to the longitudinal axis of the conductor
The cores of non-sheathed flat cords shall not be separated.
If the insulation carries an indented marling, thus giving rise to a local reduction in thickness. the test piece shall be taken so as to include such marking
8.1.4 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 focm, six measurements shall be made radially as shown in figure 1. For sector-shaped cores, six measurements shall be made as shown in figure 2.
b) When the insulation is taken from a stranded conductor, six measurements shall be made radially as shown in figures 3 and 4.
C) When the outer profile shows unevenness, the measurement shall be carried out as shown in figure 5.
d) When there are unremovable screening layers under and/or over the insulation, they shall be excluded from the measurements.
If unremovable screening layers are present under and/or over an opaque insulation, a measuring microscope shall be used.
e) Flat non-sheathed cords shall be measured according to figure 6, the thickness of insulation in the direction of the other core being taken as half the distance between the conductors.
In all cases, the first measurement shall be taken where the insulation is thinnest.
lithe insulation carries an indented marking, this shall not be included in the measurements made for the calculation of mean thickness. In any case, the thickness at the position of the indented marking shall comply with the minimum requirement specified in the relevant cable standard
The readings shall be made in millimetres to two decimal places if the specified thickness is 0,5 mm or above and to three estimated decimal places if the specified thickness of the insulation is less than 0,5 mm.
8.1.5 EvaluatIon of the m.asur.m.nt results
The results shall be evaluated as specified in the test requirements of the relevant cable standard.
In the case of mecharncal tests, the mean value of the thIckness, 8. of each test piece (see Item bi) of 91.4) shall be calculated from the six measurement results obtained on that test piece.
8.2 Measurement of thickness of non-metallic sheath
8.2.1 General
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
8.2.2 MeasurIng equipment (See 8,1.2.)
8.2.3 PreparatIon of test pieces
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 (sharp knife. razor blade. etc.>.
lithe sheath carries an indented marking, thus giving rise to a local reduction in thickness, the test piece shall be taken so as to include such marking.