SIST HD 605 S3:2019

SLOVENSKI STANDARD
01-oktober-2019
Nadomešča:
SIST HD 605 S2:2009
Električni kabli - Dodatne preskusne metode
Electric cables - Additional test methods
Starkstromkabel - Ergänzende Prüfverfahren
Câbles électriques - Méthodes d’essais supplémentaires
Ta slovenski standard je istoveten z: HD 605-S3:2019
ICS:
29.060.20 Kabli Cables
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

HARMONIZATION DOCUMENT HD 605-S3

DOCUMENT D'HARMONISATION
HARMONISIERUNGSDOKUMENT
August 2019
ICS 29.060.20  Supersedes HD 605 S2:2008 and all of its amendments
and corrigenda (if any)
English Version
Electric cables - Additional test methods
Câbles électriques - Méthodes d'essais supplémentaires Starkstromkabel - Ergänzende Prüfverfahren
This Harmonization Document was approved by CENELEC on 2019-07-01. CENELEC members are bound to comply with the
CEN/CENELEC Internal Regulations which stipulate the conditions for implementation of this Harmonization Document at national level.
Up-to-date lists and bibliographical references concerning such national implementations may be obtained on application to the CEN-
CENELEC Management Centre or to any CENELEC member.
This Harmonization Document exists in three official versions (English, French, German).
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. HD 605-S3:2019 E
Contents Page
European foreword . 4
1 General . 5
1.1 Scope . 5
1.2 Applicable tests . 5
1.3 Classification of tests . 5
1.4 Sampling . 5
1.5 Test conditions . 5
2 Non-electrical tests . 6
2.1 Dimensional measurements . 6
2.2 Mechanical tests on non-metallic components . 23
2.3 Mechanical tests on metallic components . 33
2.4 Non-electrical tests on samples of complete cable . 35
2.5 Physical and chemical tests . 63
3 Electrical tests . 76
3.1 Electrical resistance . 76
3.2 Voltage tests . 80
3.3 Insulation resistance tests . 86
3.4 Surface resistance of the cable oversheath . 89
3.5 (Spare) . 89
3.6 Spark tests . 89
3.7 Measurement of transfer impedance . 90
3.8 Heating cycle test . 92
3.9 Measurement of the electrical resistivity of the semi-conducting screens . 96
3.10 Partial discharge test . 98
3.11 Tan δ measurement . 100
3.12 Resistance of the insulating sheaths to weather conditions . 100
3.13 Adherence of screens at short circuit temperature . 103
3.14 Resistivity test for water blocking tape . 104
3.15 Moisture absorption test – Electric method . 104
3.16 (Spare) . 105
3.17 (Spare) . 105
3.18 (Spare) . 105
3.19 (Spare) . 105
4 Fire performance tests . 105
4.1 Flame propagation tests . 105
4.2 Smoke emission tests . 109
4.3 (Spare) . 111
4.4 Toxic gas emission tests . 111
4.5 (Spare) . 118
4.6 (Spare) . 118
5 Long term tests . 118
5.1 Thermal endurance tests . 118
5.2 Pulling lubricant immersion test . 120
5.3 Long term water immersion test . 120
5.4 Long term voltage test . 121
5.5 Radial watertightness test and corrosion resistance test of metallic screen. 126
5.6 Insulation water resistance test . 126
Annex A (normative) Normative references . 128
Annex B (normative) Rounding of numbers . 130
B.1 Rounding of numbers for the purpose of the fictitious calculation method . 130
B.2 Rounding of numbers for other purposes . 130
Bibliography . 132

European foreword
This document (HD 605 S3:2019) has been prepared by CLC/TC 20, “Electric cables”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2020-07-01
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2022-07-01
conflicting with this document have to be
withdrawn
This document supersedes HD 605 S2:2008 and all of its amendments and corrigenda (if any).
In order to maintain the integrity of existing clause numbers, and hence avoid unnecessary amendments to
over 100 particular sections of the product HDs, the normative references are given in Annex A.
The numbering of tables and figures in this standard is not conventional. It retains the scheme as used in
HD 605 S1. This is to facilitate easier cross referencing in national sections of HD 603, HD 620 and other
compendia HDs. It also allows for continuing work to rationalize and harmonize more of these test methods in
the future, without the need for further re-numbering.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
1 General
1.1 Scope
This HD collates and specifies the test methods to be used for testing polymeric insulated and sheathed electric
cables, of rated voltage up to and including 20,8/36 kV, intended for public distribution systems, and for use in
power generating plants and sub-stations.
Test methods in this HD are additional to those already harmonized, e.g. EN 60332-1 series and EN 60811
series, and are used for testing cable types specified in HD 603, HD 604, HD 620, HD 622, HD 626 and
HD 627. In each case, these HDs give complementary information needed for the practical application to each
specific type. Therefore the present HD as such is not sufficient for carrying out and evaluating the tests on
electric cables.
Full test conditions (e.g. temperatures, durations) and/or test requirements are not specified in this HD. Such
data needed to carry out the tests is given in the particular sections.
NOTE The words 'particular section' refer throughout to the section of HD 603 or HD 604, or other HD to which
HD 605 applies, in which a particular cable type is specified.
1.2 Applicable tests
Tests applicable to each type of cable are given in the particular section, which may also state the sequence,
the frequency of test, and the possibility of repeating failed tests.
1.3 Classification of tests
The classification of tests is given in Parts 1 of HD 603, HD 604, HD 620, HD 622, HD 626 and HD 627.
1.4 Sampling
The size and number of samples are given either in this HD or in the particular HDs.
If a marking is indented in the insulation or sheath surface, the samples used for the tests shall be taken so as
to include such markings.
For multicore cables, except for the test specified in 2.1.1, not more than three cores (of different colours, if
available) shall be tested unless otherwise specified.
1.5 Test conditions
1.5.1 Ambient temperature
Unless otherwise specified in the details for the particular test, tests shall be made at an ambient temperature
of (20 ± 15) °C.
1.5.2 Tolerance on temperature values
Unless otherwise specified in the particular specification, the tolerance on temperature values quoted in the
test methods are the following:
Table 1.5.2 — Tolerance on temperature values
Specified temperature, t
Tolerance
°C K
-40 ≤ t ≤ 0 ± 2
0 < t ≤ 50 according to relevant clause
50 < t ≤ 150 ± 2
t > 150 ± 3
1.5.3 Frequency and waveform of power-frequency test voltages
Unless otherwise specified the test voltage shall be in the range 49 Hz to 61 Hz of approximately sine-wave
form, the peak ratio value/r.m.s. value being equal to √2 with a tolerance of ± 7 %. The values given are r.m.s.
1.5.4 Pre-conditioning
Unless otherwise stated the tests shall be carried out not less than 16 h after the extrusion or cross-linking,
if any, of the insulating or sheathing compounds.
2 Non-electrical tests
2.1 Dimensional measurements
2.1.1 Measurement of insulation thickness
2.1.1.1 Procedure
The thickness of insulation shall be measured in accordance with EN 60811-201. Unless otherwise specified
one sample of cable shall be taken and measurement made at three places.
Compliance shall be checked on each core of cables having up to five cores, and on the number of cores
stated in the individual specification for cables with more than five cores.
If withdrawal of the conductor is difficult, it shall be stretched in a tensile machine or the piece of core shall be
immersed in an appropriate liquid until the insulation becomes loose.
2.1.1.2 Evaluation of results
Unless otherwise specified the mean of the 18 values (expressed in millimetres) obtained from the three pieces
of insulation from each core shall be calculated to two decimal places and rounded off as given below, and
this shall be taken as the mean value of the thickness of insulation.
If in the calculation the second decimal figure is 5 or more, the first decimal figure shall be raised to the next
number thus, for example, 1,74 shall be rounded off to 1,7 and 1,75 to 1,8.
The lowest of all values obtained shall be taken as the minimum thickness of insulation at any place.
2.1.2 Measurement of non-metallic sheath thickness
2.1.2.1 Procedure
The thickness of sheath shall be measured in accordance with EN 60811-202. Unless otherwise specified,
one sample of cable shall be taken and measurement made at three places.
2.1.2.2 Evaluation of results
The mean of all the values (expressed in millimetres) obtained from the three pieces of sheath shall be
calculated to two decimal places and rounded off as given below, and this shall be taken as the mean value
of the thickness of the sheath.
If in the calculation the second decimal figure is 5 or more, the first decimal figure shall be raised to the next
number, thus, for example, 1,74 shall be rounded off to 1,7 and 1,75 to 1,8.
The lowest of all values obtained shall be taken as the minimum thickness of sheath at any place.
2.1.3 Measurement of cable dimensions
2.1.3.1 Measurement of overall dimensions
Unless otherwise specified the three samples taken in accordance with this HD, 2.1.1 or 2.1.2 shall be used.
The measurement of the overall diameter of any circular cable and of the overall dimensions of flat cables with
a major dimension not exceeding 15 mm shall be carried out in accordance with EN 60811-203.
For the measurement of flat cables with a major dimension exceeding 15 mm, a micrometer, a profile projector
or similar equipment shall be used.
The mean of the values obtained shall be taken as the mean overall dimensions.
2.1.3.2 Measurement of ovality
For checking the ovality of circular sheathed cables, two measurements shall be made at the same cross-
section of the cable, covering the maximum and minimum values.
2.1.4 Measurement of wires, strips and tapes
2.1.4.1 Conductor wires
Measurement of the diameter of conductor wires (class 5 conductors).
(a) Sampling
Take at random either 10 % of the total number of wires, rounded upwards, or 10 wires, whichever is the
lowest, from one core of each length of cable selected for the test.
(b) Method
Determine the diameter of each wire with a micrometer by taking a measurement in three positions, approx.
300 mm far away from each other. The readings shall be made to two decimal places. Take the average of
the three measurements to be the wire diameter.
2.1.4.2 Wires and tapes for concentric conductor or screen
(a) Sampling
A sample of about 500 mm length is taken from the test piece and straightened by means of a non-damaging
tool. After that it is cleaned.
(b) Procedure
For wires and tapes the diameter or the thickness is measured with an screw type micrometer or a dial gauge
with a measuring element with flat measurement planes with a diameter 4 mm to 8 mm. Measurements shall
be made at three points which are uniformly spread along the sample.
(c) Expression of results
The diameter or the thickness is the mean value obtained from the three measurements. The test is considered
to be fulfilled if the mean value does not fall below the minimum value prescribed in the particular specification.
2.1.4.3 Wires, strips and tapes for armour
(a) Round wires
Take at random 10 wires or 10 % of the total number of wires, whichever is the smaller, from a sample of the
completed cable.
Determine the diameter of each wire of this sampling by taking two measurements at right angles to each other
using a micrometer with flat noses to an accuracy of ± 0,01 mm.
Take the average value as the wire diameter.
(b) Flat wires or strips
Take at random 10 flat wires or strips or 10 % of the total number of flat wires or strips, whichever is the smaller,
from a sample of the completed cable.
Determine the thickness and width of each flat wire of this sampling by using either a micrometer with flat
noses to an accuracy of ± 0,01 mm or a vernier calliper with flat noses to an accuracy of ± 0,02 mm.
Take the average value as the wire thickness and wire width.
(c) Metallic tapes thickness
Take and straighten a sample of each armour tape, remove the non-metallic coating if any, and determine the
tape thickness at six different places.
The measurement shall be made with either a micrometer or a vernier calliper, both with two flat noses of
approximately 5 mm in diameter, to a respective accuracy of ± 0,01 mm or ± 0,02 mm. For tapes up to 40 mm
in width the thickness shall be measured at the centre of the width. For wider tapes the measurements shall
be made 20 mm from each edge of the tape and the average of the results taken as the thickness.
Take the smallest value to be compared with the specified thickness with a tolerance given in the particular
specification.
2.1.5 Measurement of thickness of metallic sheath
The thickness of lead sheaths shall be determined by one of the following methods, at the discretion of the
manufacturer. (Methods of measuring thickness of other types of metallic sheath are under consideration.)
(a) Strip method
The measurement shall be made on a test piece of sheath about 50 mm in length removed from the finished
cable length. The test piece shall be taken a sufficient distance from the cable end to allow a proper
measurement to be made.
The piece shall be slit longitudinally and carefully flattened. After cleaning the test piece, a number of
measurements shall be taken along the circumference of the sheath and not less than 10 mm away from the
edge of the flattened piece to ensure that the minimum thickness is measured. The measurement shall be
made with a micrometer with plane faces of 2 mm to 8 mm diameter and an accuracy of ± 0,01 mm.
(b) Ring method
The measurements shall be made on a ring of the sheath carefully cut from the sample. The thickness shall
be determined at a sufficient number of points around the circumference of the ring to ensure that the minimum
thickness is measured.
The measurements shall be made with a micrometer having either one flat nose and one ball nose, or one flat
nose and a flat rectangular nose 0,8 mm wide and 2,4 mm long. The ball nose or the flat rectangular nose
shall be applied to the inside of the ring. The accuracy of the micrometer shall be ± 0,01 mm.
2.1.6 Check of application of screen or armour tapes, or wires
2.1.6.1 Method 1
Take a cable sample 300 mm long, at not less than 150 mm from the end of a factory length. Measure the gap
between adjacent edges of the tape(s), and also the tape width. Measurement is made at 4 positions along
the sample, with an accuracy better than 0,5 mm.
2.1.6.2 Method 2
Remove two rings of the oversheath each 50 mm in length, cut at a distance of 5 D and 15 D, respectively,
(where D is the overall diameter) from one end of the cable length, so as to expose the metallic tapes or wires.
Make a visual examination of the exposed components and measure the largest gap between adjacent wires
or tapes. The measurement shall be made with an accuracy better than 0,5 mm and the result shall be given
to one decimal place.
2.1.7 Percentage coverage of a braided metallic layer
The percentage coverage “B” of the braiding shall be calculated by the following formula:
100d d
B= ( + - )
m n m n mn m n
11 2 2 11 2 2
q q
where
π DS
q=
+
π D S
D = mean diameter of braiding (= diameter under metallic layer + 2 d, mm);
d = nominal diameter of the wires of the braid, mm;
S = lay of the wires of the braiding, mm;
m1 = number of spindles in one direction;
m = number of spindles in the other direction;
n1; n2 = number of wires per spindle according to the direction.
2.1.8 Measurement of the gap between non-metallic tapes of taped bedding
See 2.1.6.1
2.1.9 (Spare)
2.1.10 Irregularities of semi-conducting layers and insulation
2.1.10.1 Method 1 – Irregularities of semi-conducting conductor screen and insulation
(a) Procedure
See 2.1.10.2
(b) Requirements
(i) Irregularities of semi-conducting conductor screen (Figure 2.1.10.1 a))
The semi-conducting conductor screen shall be as far as possible free from irregularities; in any case, there
shall be no pronounced irregularities.
Sporadic irregularities may be allowed if the following requirements are complied with:
— irregularities of the semi-conducting conductor screen may not penetrate by more than 0,080 mm into the
insulation;
— when the height H of the irregularities is not less than 0,040 mm, the ratio (B)/(H) shall be greater than or
equal to 3;
— irregularities where (H) is less than 0,040 mm are not taken into consideration.
(ii) Irregularities of the insulation into semi-conducting conductor screen (Figure 2.1.10.1 b))
Irregularities of the insulation shall not penetrate into the semi-conducting conductor screen by more than
0,20 mm.
(iii) Irregularities inside the insulation (Figure 2.1.10.1 c))
Sporadic irregularities are allowed taking into account the following conditions:
— Irregularities for which the maximum dimension (L) is less than 0,05 mm are not considered;
— Irregularities for which the maximum dimension (L) is greater than 0,20 mm are not authorized;
— If irregularities are observed for which the maximum dimension (L) is greater than 0,05 mm but less than
or equal to 0,20 mm a second sample, taken close to the first one, shall be examined and shall not be
permitted to show irregularities.

a) Irregularities of semi- b) Irregularities of the insulation c) Irregularities inside the
conducting conductor screen into the semi-conducting insulation
conductor screen
Key
1 Insulation B Base of the irregularity
2 Semiconducting screen H Height of the irregularity
3 Conductor M Penetration depth of the irregularity
L Dimension of the irregularity
Figure 2.1.10.1 — Method 1 – Irregularities of semi-conducting conductor screen and insulation
2.1.10.2 Method 2 – Irregularities of semi-conducting conductor screen and insulation
(a) Scope
This standard specifies the tests of irregularities of the surface of extruded inner semi-conducting layers and
in insulation of XLPE insulated power cables with rated voltages Uo/U 6/10 kV to 20,8/36 kV.
(b) Measuring equipment
(i) electrical air oven with natural air flow
(ii) beaker
(iii) silicone oil
(iv) measuring microscope or profile projector of at least 10x magnification, with rotating holding device for
the test piece, which shall allow for a reading of 0,01 mm
(v) illumination
(c) Preparation of test pieces
From one end of the cable a test piece of 300 mm in length shall be taken. The outer semi-conducting layer of
the test piece will be removed. The test piece may be stored for one to two hours in the air oven ((b) (i)) at
approximately 80 °C. The beaker ((b) (ii)) shall be filled with silicone oil ((b) (iii)) and heated to approximately
130 °C.
(d) Measuring procedure
The test piece shall be inserted into the heated silicone oil until the XLPE insulation reaches its full
transparency. The test piece shall then be visually inspected with the assistance of the lamp ((b) (v)) and, if
necessary, any irregularities on the surface of the test piece shall be marked. The test piece shall then cool
down to room temperature.
In order to measure the irregularities the test piece shall be cut into discs or spirals at the points marked. The
measurement of the irregularities shall be carried out by means of the measuring equipment ((b) (iv)) in such
a manner that,
— the largest extension (b) of an irregularity in the insulation (Figure 2.1.10.2 a));
— the largest extension (t) of an irregularity in the inner semi-conducting layer (Figure 2.1.10.2 b));
— the largest extension (h) of an irregularity in the inter-facial area semi-conducting layer/insulation into the
insulation and its basis diameter (d) (Figure 2.1.10.2 c));
shall be ascertained.
(e) Evaluation of test results
The results are acceptable if the measured values are with the limits given in the particular specifications.

a) Irregularities in the insulation b) Irregularities extended into c) Irregularities of the conductor
the conductor screen screen extended into the
insulation
Key
1 Insulation b Dimension of the irregularity
2 Semiconducting screen t Penetration depth of the irregularity
3 Conductor d Base of the irregularity
h Height of the irregularity
Figure 2.1.10.2 — Method 2 – Irregularities of semi-conducting conductor screen and insulation
2.1.10.3 Method 3 – Imperfection in cross-linked polyethylene insulation and semi-conducting
layers
(a) Cross-linked Polyethylene Insulation
The insulation material shall be inspected for contaminants using a continuous sampling plan. The plan shall
sample a minimum of 2 % of the insulation material volume. The material analysis shall be reported for
engineering information only and at a minimum, list the size and a number of contaminants found per weight
of insulation inspected. Material that is not inspected by the producer, shall be inspected at the 2 % rate by the
cable supplier.
The insulation of the completed cable shall be free from:
(i) Any void larger than 0,075 mm. The number of voids larger than 0,05 mm shall not exceed two per cubic
cm of insulation for all voltages.
(ii) Any contaminant (opaque material or material that is not homogeneous cross-linked polyethylene) larger
than 0,125 mm in its greatest dimension. The number of contaminants of sizes between 0,05 mm and
0,125 mm shall not exceed one per cubic cm of insulation for all voltages.
(iii) Any translucent material that is larger than 1,25 mm in its greatest dimension.
(b) Semi-conducting conductor and insulation screen voids and protrusions
1. Semi-conducting extrusion for conductor shielding shall be free of any voids larger than 0,075 mm at
the insulation interface.
2. Semi-conducting extrusion for insulation shielding shall be free of any voids larger than 0,125 mm at
the insulation interface.
3. The contact surface between semi-conducting extrusion shields and the insulation shall be cylindrical
and free from protrusion and irregularities which, at the conductor shield, extend by more than
0,125 mm into the insulation and 0,25 mm into the conductor shield. Protrusions at the surface
between insulation and insulation shield shall be limited to 0,25 mm into the insulation and 0,25 mm
into the insulation shield.
The conductor shielding shall be extruded and shall consist of black, semi-conducting material compatible with
the insulation and the conductor and shall have allowable operating temperatures equal to or higher than those
of the insulation. The outer surface of the conductor shield shall be cylindrical and shall be firmly bonded to
the overlying insulation. The extruded shield shall be easily removable from the conductor. The average
minimum thickness shall be 0,40 mm.
A semi-conducting tape may be used between the conductor and the extruded semi-conducting material. The
insulation shielding shall be extruded and shall consist of black, semi-conducting thermoplastic or cross-linked
material applied directly over the insulation.
(c) Method for determination of voids, contaminants, translucents and protrusions
(i) Samples shall be prepared as follows: 50 mm of the sample shall be cut helically or in some other
convenient manner to produce thin samples of the conductor shield, insulation and insulation shield.
Wafers (or the turns of the helix) shall be approximately 0,6 mm thick (producing approximately
80 wafers). The cutting blade shall be sharp and shall produce a sample with uniform thickness and
with very smooth cut surfaces. The sample shall be kept clean and shall be handled carefully to
prevent scratching the cut surfaces.
(ii) The entire specimen shall be viewed by transmitted light for general determination of freedom from
voids, contaminants, and translucent materials in the insulation and between the insulation and
conductor and insulation shield. For mineral-filled cross-linked polyethylene insulated cables, and
conductor shields, the reflected light method shall be used.
1. A contaminant is any solid or liquid material which is opaque or not homogeneous thermoplastic
of cross-linked polyethylene insulation, including discoloured, translucent material of more than
1,25 mm in its greatest dimension.
2. The entire area of 20 consecutive wafers (or equivalent turns of the helical sample) shall be
examined with a minimum of 15-power magnification, including any areas which appear suspect
during the above examination by transmitted light.
3. A tabulation of numbers and sizes shall be made with a minimum of 15-power magnification of:
(a) all voids, 0,05 mm in greatest dimension and larger; and
(b) all contaminants, 0,05 mm in greatest dimension and larger in cross-linked polyethylene;
and
(c) discoloured, translucent material of more than 0,05 mm in its greatest dimension.
This tabulation shall be recorded and reported.
4. The largest void, the largest contaminant and the largest translucent material shall be marked by
encircling and shall be subsequently measured on a micrometer microscope.
5. The number of voids, contaminants and translucents expressed per cubic cm of insulation shall
be calculated from the tabulation. (The volume of the 20 wafers, or equivalent turns, may be
determined by any convenient method.) If the 20 wafers constitute less than 16,4 cm and if the
void or contaminant count exceeds the allowable number specified in the relevant cable
specification then a sufficient number of wafers from the sample shall be examined to a total of
3 3
16,4 cm of insulation (16,4 cm = 1 cubic inch).
(iii) The largest void, contaminant and translucent material marked on the sample shall be measured with
a micrometer microscope using a minimum of 40 power magnification. The largest dimension shall
be measured only. If voids, contaminants or translucents exceed the limits listed in the relevant cable
specification the sample shall be considered to have failed to meet the test requirements.
(iv) The contact area between the insulation and the shield extrusions (both the conductor shield and the
insulation shield) on the 20 wafers or equivalent turns shall also be examined, using a minimum of
15-power magnification. The sample shall be considered to have failed to meet the test requirements
if the contact surface between these extrusions and the insulation has protrusions or irregularities
which exceed the limits specified in the relevant cable specifications.
2.1.10.4 Method 4 – Counting of voids and contaminants in insulation
Take a sample of insulation 5 cm long.
Cut the insulation into thin slices and check against light. Some 20 slices, specially if offering doubts shall be
observed with an amplification of 15x.
For counting voids and contaminants use always an amplification of 15x.
(a) Count:
— Every void with a diameter ≥ 50 µm
— Every contaminant with the larger dimension ≥ 50 µm
(b) Measure:
— Dimension of largest void and largest contaminant with an amplification ≥ 40x.
(c) Determine:
— Number of voids and contaminants per 10 cm of material.
If the number of voids or contaminants per 10 cm exceeds the accepted values, and the volume of insulation
3 3
inspected is less than 10 cm , more examinations shall be done, until 10 cm of material is examined.
2.1.10.5 Method 5 – Method for inspection for protrusions, contaminants and discoloured particles
in XLPE insulation
This test method is to determine the presence of discontinuities at the semi-conducting screen/insulation
interfaces and the presence of contaminants (opaque impurities) and discoloured particles in the insulation.
(a) Sample preparation
Test pieces shall be prepared from 300 mm lengths of core. Samples 25 mm long shall be cut from each end
of the core to give Samples A1 and A2.
The remaining portion shall be cut into two pieces of equal length to give Samples B and C.
The insulation screen shall be removed from Sample B and this shall be cut into further pieces to give Samples
B1 and B2.
(b) Test method to determine discontinuities
Immerse test pieces A1 and B1 in glycerol or polyethylene glycol or similar liquid contained in a glass beaker
and maintained at 130 °C - 150 °C, or alternatively heat up the samples in an air oven to a similar temperature.
Allow the test pieces to attain the approximate liquid or air temperature such that the insulation becomes
transparent.
The interfaces shall be examined in a good light with normal or corrected vision without magnification.
Examine by viewing along the conductor axis the conductor screen/insulation and insulation screen/insulation
interfaces and the insulation of the Sample A1, and by viewing radially the conductor screen/insulation interface
and the insulation of the second Sample B1.
The conductor and insulation screens shall be bonded to the insulation with no traces of dissociation between
them (see Figure 2.1.10.5 a)). There shall be no detectable traces of any inclusions between the screen and
the insulation (see Figure 2.1.10.5 b)). The insulation material shall not have broken through the screen (see
Figure 2.1.10.5 c)) nor shall there be any penetration of the insulation by the screen material (see
Figure 2.1.10.5 d)).
Repeat for the remaining Samples A2 and B2.
a) Dissociation of bonding between insulation and b) Inclusions between screen and insulation
conductor and insulation screens

c) Insulation breaking through screen d) Penetration of screen into insulation
Key
1 Insulation screen 3 Conductor screen
2 Insulation
Figure 2.1.10.5 — Dissociation, inclusion and penetration
(c) Test method to determine contaminants and discoloured particles
Samples for examination shall be produced by cutting wafers from Sample C.
At least 5 cm of insulation shall be examined using a microscopic based measuring system at a minimum
magnification of 20x.
Requirements are:
(i) Contaminants
— 0,05 mm < largest dimension ≤ 0,15 mm 1 per cm maximum
— 0,15 mm < largest dimension - rejected
(ii) Discoloured particles
— 1,25 mm < largest dimension - rejected
2.1.10.6 Method 6 – Microscopic examination of insulation and semi-conducting layers
(a) Scope
Product XLPE insulated conductor, U > 3 kV
Operation Insulation extrusion
Sampling At the beginning and end of each extrusion run and at each change of drum, length of sample
10 cm
Test equipment Stereo measuring microscope, with suitable range of magnification
(b) Inspection method
A sample of sufficient length shall be cut to yield a number of wafers (thickness approximate 1 mm) of at least
10 cm of insulation for the inspections detailed below.
(i) All wafers shall be viewed by transmitted light to find the largest defects in the insulation and in the contact
areas between semi-conducting layers and insulation.
(ii) All wafers shall then be examined with a minimum of 15-power magnification by transmitted light to find
the defects in the insulation and in the contact areas between semi-conducting layers and insulation.
The defects in insulation are classified into three types:
— voids
— contaminants (opaque impurities and non-homogeneously crosslinked polyethylene particles);
— translucent, discoloured polyethylene particles.
The irregularities in the contact areas between semi-conducting layers and insulation are classified into
— voids
— protrusions
— grooves
— pits.
(iii) All defects and irregularities detected in the insulation and in the contact areas between semi-conducting
layers and insulation shall be marked by encircling, numbered and tabulated. They shall also be
calculated.
(iv) The largest defect and irregularity shall be measured with a minimum of 40-power magnification. The
largest dimension (d) shall be recorded for each defect.
The requirements for the defects and irregularities are given in the relevant standard.
2.1.11 Dimensions of cores
2.1.11.1 Method 1 – XLPE insulated cores for cables with rated voltages U /U 6/10 kV to 18/30 kV
o
(a) Scope
This test specifies the determination of wall thicknesses of semi-conducting layers and of insulation, the
diameters over insulation and outer semi-conducting layer as well as the roundness of XLPE insulated cores
with circular conductors of power cables with rated voltage U /U 6/10 kV to 18/30 kV.
o
(b) Measuring equipment
A measuring microscope or a profile projector of at least 10 times magnification, with rotating holding device
for the test piece, which shall allow for a reading of 0,01 mm.
(c) Preparation of test pieces
One test piece shall be taken from both ends of the cable length to be tested. All cable elements above the
cable core shall be removed from the test piece. The conductor may be removed. In cases of doubt however,
the measurements shall be made on samples with the conductor in place. The prepared test pieces are cut
vertically to the longitudinal axle and the cut surface of the core so prepared that the limits of the individual
elements to be tested are clearly recognized. The test pieces shall be inserted into the rotating holding device
of the measuring tool (b), so that the surface stands vertically to the optical axis of the measuring equipment.
(d) Measuring procedure
The measurements of wall thicknesses and diameters shall be started from the thinnest point of the insulation
and be made at 60° intervals around the circumference (Figure 2.1.11.1 a)). This results for each test piece in
six wall thicknesses and three diameter values for the insulation and the insulation screen. For test pieces
which cannot be measured in one operation, it is admissible to obtain the values by addition of partial
measurements.
If the outer surface of the insulation screen shows irregularities a measure up to the half height of such
irregularities, with the crosshairs laid on as per Figure 2.1.11.1 b) shall be made. For measurements of the
conductor screen with stranded conductors the wall thickness shall be measured at the thinnest place. The
crosshairs of the measuring equipment shall be applied according to Figure 2.1.11.1 c) or Figure 2.1.11.1 d).
(e) Evaluation of measured results
(i) Wall thickness of semi-conducting inner layer
The individual values of the wall thickness of conductor screening shall be the result at the measurements
between the measuring points 2 and 3 as well as 4 and 5 according to Figure 2.1.11.1 a). The results shall be
acceptable if none of the six values ascertained falls below the minimum value specified in the standard for
power cables.
(ii) Wall thickness of insulation
The individual values of the wall thickness of the insulation shall be the result of the measurements between
the measuring points 1 and 2 as well as 5 and 6 according to Figure 2.1.11.1 a). The results shall be acceptable
if the average value of the six values ascertained does not fall below the nominal value specified in the standard
for power cables.
(iii) Uniformity of wall thickness of insulation
The individual values for the wall thickness of the insulation shall be the result of the measurements between
the measuring points 1 and 2 as well as 5 and 6 according to Figure 2.1.11.1 a). The results shall be acceptable
if the difference between the largest and the smallest value of the six values ascertained does not exceed the
maximum value specified in the standard for power cables.
(iv) Diameter of insulation
The individual values of the diameter of the insulation shall be the result of the measurement between the
measuring points 1 and 6 according to Figure 2.1.11.1 a). The results shall be acceptable if the average value
of the three values determined does not fall below the minimum value and not exceed the maximum value as
specified in the standard for power cables.
(v) Wall thickness of semi-conducting outer layer
The individual values of the wall thickness of the insulation screen shall be the result of the measurement
between the measuring points 0 and 1 as well as 6 and 7 according to Figure 2.1.11.1 a). The result shall be
acceptable if none of the six values ascertained falls below the minimum value or exceeds the maximum value
as specified in the standard for power cables.
(vi) Concentricity of core
The individual values of the dia
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