EN 50305:2002

SLOVENSKI STANDARD
01-november-2002
Railway applications - Railway rolling stock cables having special fire performance
- Test methods
Railway applications - Railway rolling stock cables having special fire performance - Test
methods
Bahnanwendungen - Kabel und Leitungen für Schienenfahrzeuge mit verbessertem
Verhalten im Brandfall - Prüfverfahren
Applications ferroviaires - Câbles pour matériel roulant ferroviaire ayant des
performances particulières de comportement au feu - Méthodes d'essais
Ta slovenski standard je istoveten z: EN 50305:2002
ICS:
13.220.20 3RåDUQD]DãþLWD Fire protection
29.060.20 Kabli Cables
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50305
NORME EUROPÉENNE
EUROPÄISCHE NORM July 2002
ICS 13.220.20; 29.060.20; 45.060.01
English version
Railway applications -
Railway rolling stock cables having special fire performance -
Test methods
Applications ferroviaires - Bahnanwendungen -
Câbles pour matériel roulant ferroviaire Kabel und Leitungen für Schienenfahrzeuge
ayant des performances particulières mit verbessertem Verhalten im Brandfall -
de comportement au feu - Prüfverfahren
Méthodes d'essais
This European Standard was approved by CENELEC on 2002-07-02. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50305:2002 E
Foreword
This European Standard was prepared for the Technical Committee CENELEC TC 20, Electric cables
by WG 12, Railway cables, on behalf of the Technical Committee CENELEC TC 9X, Electrical and
electronic applications for railways.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by
CENELEC as EN 50305 on 2002-07-02.
The following dates were fixed:
- latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2003-07-01
- latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-07-01
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes B and E are normative and annexes A, C and D are informative.
__________
– 3 – EN 50305:2002
Contents
Introduction.5
1 Scope.6
2 Normative references.6
3 Definitions.7
4 Applicability, sampling, test-piece preparation and test conditions.7
4.1 Applicable tests.7
4.2 Classification of tests .7
4.3 Sampling.7
4.4 Test-piece preparation .7
4.5 Test conditions.7
5 Mechanical tests.8
5.1 Impact test at low temperature .8
5.2 Abrasion resistance.8
5.3 Notch propagation.9
5.4 Pliability .10
5.5 Strippability and adhesion of insulation.11
5.6 Dynamic cut-through.11
6 Electrical tests.12
6.1 Electrical resistance of conductors .12
6.2 Voltage test on completed cable.12
6.3 Voltage test on sheath.12
6.4 Insulation resistance .13
6.5 Spark test .13
6.6 Surface resistance .14
6.7 D.C. stability .14
6.8 Dielectric strength .15
7 Ageing and thermal tests.15
7.1 Compatibility .15
7.2 Long term ageing for insulation .15
7.3 Long term ageing for sheath.19
7.4 Ozone resistance.19
7.5 Pressure test at high temperature .21
7.6 Shrinkage test for insulation .21
7.7 Stress cracking test.21
8 Tests in fluids, including water.23
8.1 Mineral and fuel oil resistance .23
8.2 Acid and alkali resistance.23
8.3 Water absorption of sheath .23
9 Reaction to fire tests .24
9.1 Flame propagation.24
9.2 Toxicity .24
10 Miscellaneous tests.27
10.1 Durability of marking .27
10.2 Blocking of cores.27

Annex A (informative) List of other test methods applicable to rolling stock cables .29
Annex B (normative) Procedure for checking the efficacy of the method of spark testing (with
reference to 6.5) .30
Annex C (informative) Long term ageing test – Significance and use.32
Annex D (informative) Illustration of an Arrhenius plot.33
Annex E (normative) Analysis methods for toxicity .34
Figure 1 – Test arrangement for abrasion of insulation and sheath.9
Figure 2 – Pliability test rig .10
Figure 3 – Assembly for adhesion test.11
Figure 4 – Arrangement of electrodes for test sample.14
Figure 5 – Suggested method of attachment of insulated wire test specimen to mandrel .18
Figure 6 – Clamping device.20
Figure 7 – Flat topped cone .22
Figure 8 – Schematic diagram of apparatus for production, collection and analysis of gases.26
Figure B.1 – Removal of insulation segment.30
Figure B.2 – Overlap position for tape .31
Table 1 – Tolerances for temperature values.7
Table 2 – Parameters for impact test at low temperature.8
Table 3 – Recommended exposure times in days per cycle.17
Table 4 – Requirements for wrapping test .17
Table 5 – Determination method to be applied .25
Table 6 – CC values for various gases .27
z
– 5 – EN 50305:2002
Introduction
The railway industry is generally concerned with the movement of people as well as goods. It is
therefore essential that a high level of safety is achieved, even when failures occur which may involve
fire, howsoever caused, affecting railway rolling stock.
Hence it is necessary to provide cables for use in railway environments which minimise the hazard to
people when a fire may damage the cable, irrespective of whether the fire is caused by an external
source or from within the electrical system.
European Standards EN 50264 and EN 50306 specify cables which, in the event of fire will limit risk to
people and improve the safety on railways in general. They cover cables based on halogen free
materials, for use in railway rolling stock.
EN 50264 covers a range of sheathed and unsheathed cables, with standard wall thickness of
2 2
insulation, rated at up to 3,6/6 kV with conductor sizes 1,0 mm up to 400 mm .
EN 50306 covers a range of sheathed and unsheathed cables with thin wall insulation, and restricted
to a rating of 300 V to earth and a maximum conductor size of 2,5 mm .
This standard EN 50305, gives particular test methods applicable to the cables at present covered by
EN 50264 and EN 50306.
1 Scope
This standard specifies special test methods applicable to cables, and their constituent insulating and
sheathing materials, for use in railway rolling stock. Such cables are specified in the various parts of
EN 50264 and EN 50306.
Other test methods required for railway rolling stock cables and their insulating and sheathing
materials are listed in Annex A.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
EN 50264-1 Railway applications - Railway rolling stock cables having special fire
performance - Standard wall -- Part 1: General requirements
EN 50266-2-4:2001 Common test methods for cables under fire conditions - Test for vertical flame
spread of vertically-mounted bunched wires or cables -- Part 2-4: Procedures -
Category C
EN 50267-1 Common test methods for cables under fire conditions – Test on gases evolved
during combustion of materials from cables -- Part 1: Apparatus
EN 50306-1 Railway applications - Railway rolling stock cables having special fire
performance - Thin wall -- Part 1: General requirements
EN 60216-1 Electrical insulating materials - Properties of thermal endurance -- Part 1:
Ageing procedures and evaluation of test results (IEC 60216-1)
EN 60811-1-1 Insulating and sheathing materials of electric cables - Common test methods --
Part 1-1: General application - Measurement of thickness and overall
dimensions - Tests for determining the mechanical properties (IEC 60811-1-1)
EN 60811-1-2 Insulating and sheathing materials of electric cables - Common test methods --
Part 1-2: General application - Thermal ageing methods (IEC 60811-1-2)
EN 60811-1-3 Insulating and sheathing materials of electric cables - Common test methods --
Part 1-3: General application - Methods for determining the density - Water
absorption tests - Shrinkage test (IEC 60811-1-3)
EN 60811-1-4 Insulating and sheathing materials of electric cables - Common test methods --
Part 1-4: General application - Test at low temperature (IEC 60811-1-4)
EN 60811-3-1 Insulating and sheathing materials of electric cables - Common test methods --
Part 3-1: Methods specific to PVC compounds - Pressure test at high
temperature - Tests for resistance to cracking (IEC 60811-3-1)
ISO 6349 Gas analysis - Preparation of calibration gas mixtures - Permeation method
ISO 8458-2 Steel wire for mechanical springs -- Part 2: Cold-drawn carbon steel wire

– 7 – EN 50305:2002
3 Definitions
The definitions given in EN 50264-1 and EN 50306-1, shall apply to this standard.
4 Applicability, sampling, test-piece preparation and test conditions
4.1 Applicable tests
Tests applicable to each type of cable are given in the particular cable standard.
4.2 Classification of tests
The classification of tests is given in the general requirements of the relevant cable standard.
4.3 Sampling
The size and number of samples for each particular test is given either in this EN or the relevant cable
standard.
4.4 Test-piece preparation
The preparation of test pieces shall be as described in the particular test method or in the cable
standard.
NOTE  Attention is drawn to the fact that some insulation systems used for railway cables are composites (multilayer). In such
cases special preparation techniques and requirements are given in the particular cable standard.
4.5 Test conditions
4.5.1 Ambient temperature
Tests shall be made at an ambient temperature within the range 5 °C to 35 °C, unless otherwise
specified in the details for the particular test.
4.5.2 Tolerance on temperature values
The tolerances which shall apply to the temperature values are given in Table 1.
Table 1 – Tolerances for temperature values
Specified Tolerance
temperature (T)
°C °C
-40 � T � 0 � 2
According to
0 < T � 50
relevant clause
50 < T � 150 � 2
T > 150 � 3
4.5.3 Frequency and waveform of power frequency test voltages
Unless otherwise specified, the test voltage shall be a.c. 49 Hz to 61 Hz of approximately sine-wave
form; the ratio peak value/r.m.s. value being equal to �2 with a tolerance of � 7 %.
The values quoted are r.m.s. values.

4.5.4 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.
5 Mechanical tests
5.1 Impact test at low temperature
The impact test in accordance with 8.5 of EN 60811-1-4 shall be used except that the mass of
hammer, intermediate test piece and height of drop shall be as given in Table 2.
Table 2 – Parameters for impact test at low temperature
Cable Mass of Mass of intermediate Height of
diameter (D) hammer test piece drop
mm g g mm
1 000 200 100
D � 15
1 500 200 150
15 < D � 25
D > 25 2 000 200 200
The inside and outside of the sheath and the insulation of unsheathed cables shall then be examined
with normal or corrected vision, without magnification. The insulation of sheathed cables shall be
examined on the outside only.
5.2 Abrasion resistance
The test shall be carried out at a temperature of (20 � 5) °C, using a machine similar to that shown in
Figure 1.
The cutting edge shall be either a polished steel spring wire needle of (0,45 ± 0,01) mm diameter, and
of material according to ISO 8458-2, held in a suitable support (Figure 1 b)), or a rectangular shaped
steel blade (Figure 1 a)) mounted at 90° to the axis of the cable. The setting shall be arranged so as
to wear the surface of the core or cable lengthwise over a distance of 10 mm to 20 mm, with a
frequency of (55 � 5) cycles per minute. The machine shall be fitted with a counter which shall stop
automatically when the cutting edge touches the conductor or electrical screen.
For cables of diameter less than or equal to 6 mm the needle shall be used, and for cables with
diameter greater than 6 mm the steel blade shall be used, unless otherwise specified in the particular
cable standard.
The load on the cutting edge shall be defined in the cable standard.
The test specimen shall consist of a single 0,75 m sample of core or cable.
The test specimen shall be held securely on the plate by 2 cable clamps.
Each test specimen shall undergo four tests. After each single test it shall be moved approximately
100 mm and turned by a 90° angle, clockwise.
NOTE  In the case of 2 core cables, 3 core cable or those cables not substantially circular, the cutting edge should be applied
to the highest points on the circumference of the cable.
Each test is finished when the cutting edge touches the conductor or electrical screen.

– 9 – EN 50305:2002
The measure of abrasion resistance shall be the average value of the number of cycles in the four
tests.
a) Detail X b) Detail Y
(edges not rounded; free of burr)
Dimensions in millimetres
Key
1 Stroke generator 7 Fastening screw
2 Stroke 8 Blade reamer
3 Loading weight 9 Shoulder of sufficient depth
to clear insulation
4Clamp
5 Test specimen 10 Cutting edge - needle
6 Supporting plate 11 Cable under test
Figure 1 – Test arrangement for abrasion of insulation and sheath
5.3 Notch propagation
Three samples of the cable shall be notched, to a depth of 0,05 mm of the insulation or sheathing, at
four points equally spaced with respect to one another around the circumference and 25 mm apart
along the length, and in a plane mutually perpendicular to the conductor.
NOTE  In the case of 2 core cable, 3 core cable or those cables not substantially circular, the notches should be made at the
highest points on the circumference of the cable.

One of the samples shall be conditioned at -15 °C, one at ambient temperature and one at 85 °C, in all
cases for 3 h, after which time they shall be wound on to a mandrel, (3 ± 0,3) times the minimum
specified diameter of the cable, whilst at the conditioning temperature. The notched sample shall be
wrapped around the mandrel such that at least one notch is on the outside of the cable.
The sample shall be allowed to return to ambient temperature and then subjected to the voltage test
given in 6.2. but at half the rated voltage U .
5.4 Pliability
From a single coil of cable cut consecutive test specimen lengths, each of approximately 200 mm.
Suspend each specimen vertically for 24 h in an oven with a mass attached to its free end. The
applied mass and oven temperature shall be as stated in the cable specification. Immediately after
removal from the oven, store the specimens at the temperature, relative humidity and period of time
specified in the cable specification.
Test each specimen using the test rig shown in Figure 2; the diameter of the mandrel in the test rig
shall be as the minimum bend diameter unless specified in the cable specification. Gradually apply a
mass to the cable, at the position shown in Figure 2, sufficient to bend the cable downwards through
(90 )°.
-1
Ensure that the specimen remains in this position for 5 min and record the mass. After this time,
remove the mass and allow the specimen to recoil towards its original position. At a time 5 min after
removal of the mass, record the recoil distance.
Dimensions in millimetres
Key
1Clamp
2 Mandrel
3 Test specimen
4 Mass container
5 Recoil
Figure 2 – Pliability test rig

– 11 – EN 50305:2002
5.5 Strippability and adhesion of insulation
5.5.1 Strippability
Stripping of 5 mm of insulation from each end of a 50 mm sample shall be easily carried out with
normal stripping pliers.
5.5.2 Adhesion
Three test specimens, each of 50 mm length, shall be cut at regular intervals from a test sample of
3 m of core or cable.
On each specimen the insulation shall be cut 5 mm and 30 mm from one end. The insulation shall be
stripped from the cuts to each end, so that insulation is left intact in-between the two cuts. The core
shall then be passed through a calibrated hole the diameter of which is that of the core + 0,05 mm
(see Figure 3).
Using a pulling speed of (100 � 10) mm/min a force shall be applied to the conductor until it slips
inside the insulation. The force (F) required to produce the slippage shall be recorded.
Dimensions in millimetres
Figure 3 – Assembly for adhesion test
5.6 Dynamic cut-through
A tensile tester (or equivalent apparatus) shall be operated in a compression mode and shall be
equipped with a means to record the force necessary to drive the needle cutting edge (see
Figure 1 b)) through the insulation or sheath of a finished sample of cable. A low voltage detection
circuit, designed to stop the tester when the edge cuts through the cable insulation or sheath and
contacts the conductor or electrical screen, shall be attached.
Carry out the test at the temperature specified in the individual cable specification. The force on the
cutting edge driving it through the insulation or sheath shall be increased at the constant rate as
specified in the product standard until contact with the conductor or metallic screen occurs. Perform
four tests on each test sample, and record the force measured at electrical contact. Move the sample
forward a minimum of 25 mm and rotate 90° clockwise between each test.
NOTE  In the case of 2 core cables, 3 core cable or those cables not substantially circular, the cutting edge should be applied
to the highest points on the circumference of the cable.
The average of the four results shall not be less than the specified minimum.

6 Electrical tests
6.1 Electrical resistance of conductors
The electrical resistance of each conductor shall be measured on a sample of cable of at least 1 m in
length, and the length of this sample shall be measured.
If necessary a correction to 20 °C and to a length of 1 km shall be obtained by the formula:
254,5 1000
RR�� �
20 t
234,5� t L
where
t = temperature of the sample at the moment of measurement, in degrees Celsius;
R = resistance at 20 °C, in ohm/kilometre;
R = resistance of L metres of cable at t °C in ohm;
t
L = length of the sample of cable, in metres (length of the complete sample and not of the
individual cores or wires)
The measured resistance shall not exceed the value in the particular standard.
6.2 Voltage test on completed cable
6.2.1 Cable without metallic layer
If the cable has no metallic layer, a sample of the cable as delivered shall be immersed in water for a
minimum period of 1 h. The length of the sample, the temperature of the water and the duration of
application of voltage shall be as given in the cable specification.
A voltage shall be applied in turn between each conductor and all the others connected together and to
the water.
6.2.2 Cable with one or more metallic layers
a) If the cable has a metallic layer, a sample of the cable shall be taken of the length defined in the
cable specification.
A voltage shall be applied in turn between each conductor and all the others connected together
and to the metallic layer.
The voltage and the duration of its application are given for each case in the cable specification.

b) If the cable has more than one screened and sheathed unit a sample of the complete cable shall
be taken of the length defined in the cable specification.
A voltage shall be applied in turn between each screen and all other screens and conductors
connected together.
The voltage and the duration of its application are given for each case in the cable specification.
6.3 Voltage test on sheath
The test shall be made on sheathed cable where there is a metallic screen or braid under the sheath.
A length of complete cable shall be immersed in water, and an a.c. or a d.c. voltage applied between the
metallic screen or braid and the water.
The sample length, test temperature, voltage level and duration of its application shall be as given in the
particular cable standard.
– 13 – EN 50305:2002
6.4 Insulation resistance
6.4.1 Test at ambient temperature
The test shall be made on the core samples, 5 m long, previously submitted to the test described in 6.2.1.
The sample shall be immersed in water at ambient temperature; a length about 0,25 m at each end of
the sample being kept above the water. The duration of immersion shall be a minimum of 1 h.
A d.c. voltage of between 80 V and 500 V shall be then applied between the conductor and the water.
The insulation resistance shall be measured one minute after application of the voltage and this value
shall be corrected to 20 °C and related to 1 km.
6.4.2 Test at elevated temperature
The test shall be made on the core samples, 5 m long.
The sample shall be immersed in water previously heated to 90 °C; a length of about 0,25 m at each
end of the sample being kept above the water. The duration of immersion shall be a minimum of 1 h.
A d.c. voltage of between 80 V and 500 V shall then be applied between the conductor and the water.
The insulation resistance shall be measured one minute after application of the voltage and this value
shall be related to 1 km.
6.5 Spark test
6.5.1 General
This test shall be carried out as a routine test in the final stage of manufacture either on delivery lengths
or on manufacturing lengths before cutting them into delivery lengths.
The test shall be carried out either on insulated cores or on the sheath of cable where there is a metallic
screen or braid under the sheath.
6.5.2 Method
Test requirements : The cable shall withstand the test voltage specified in the particular cable standard
without failure of the insulation or sheath as appropriate. The spark test equipment shall detect a puncture
in the insulation or sheath having a diameter equal to or greater than half of the specified insulation or
sheath thickness. The recovery time of the spark tester shall be not greater than one second.
Test voltage : The voltage applied by the spark tester may be power frequency a.c., d.c., high frequency
or of other form.
The magnitude and the presence of the voltage shall be such that with the electrode system employed
and at the speed employed for the passage of the cable through the spark tester the test requirements
are effectively met.
The reference method to be used to establish the efficacy of the spark testing equipment is given in
Annex B.
6.6 Surface resistance
The test specimen shall be prepared as follows.
Each specimen shall have two annular electrodes fitted as shown in Figure 4. The two electrodes shall
consist of copper wire with a diameter of about 1,8 mm and they shall be arranged in the centre part of
the specimen with their internal windings about 50 mm from each other. When positioning the
electrodes it is essential to avoid any serious indentation of the wire into the protective cover.
The specimens, fitted with their electrodes, shall be immersed in water held at (20 � 5) °C for 4 h with
the ends of the specimen protruding by about 50 mm above the level of the water.
Upon completion of this operation, the specimens shall be removed from the water and excess water
removed from their surfaces.
The specimens prepared in this way shall be immediately subjected to 2,0 kV a.c. applied between the
electrodes. The leakage current shall be measured, using an appropriate ammeter, between the two
electrodes after 30 s voltage application.
Immediately after the determination of the leakage current, the voltage applied between the electrodes
shall be increased at a constant rate of 100 V/s until breakdown occurs or the voltage limit given in the
particular specification is exceeded.
Dimensions in millimetres
Key
1 Copper wire
2 Test specimen
3 Water level
Figure 4 – Arrangement of electrodes for test sample
6.7 D.C. stability
A test specimen of minimum length of 5 m of cable shall be immersed in distilled water containing 3 %
NaCl. At least 300 mm of additional cable shall protrude at each end. The salt solution shall be
maintained at an elevated temperature of (85 � 2) °C for (240 � 2) h, and the specified voltage applied
between the conductor and the salt solution with the conductor at the negative potential. The test shall
then be repeated, using a new test specimen, with the conductor at the positive potential.
The current flowing in the circuit shall be measured periodically throughout the test at intervals not
greater than 24 h. Continuous measurement is preferred, if possible.
The current measurement data shall be plotted in the form of a current versus time curve and shall
indicate an approach to a period of stability.

– 15 – EN 50305:2002
NOTE  A period of stability is, for instance, less than 10 % increase in current leakage averaged over any 24 h period (this is
subject to review in the light of practical experience).
On completion of the immersion, the cables shall be removed from the salt solution and subjected to
the voltage test specified in 6.2 except that the test voltage shall be the rated voltage (U) of the cable,
unless otherwise specified.
6.8 Dielectric strength
5 m of cable sample shall be immersed in water for a period as given in the cable standard,
maintained at a temperature of (20 � 5) °C with at least additional lengths of 150 mm protruding at
each end. The voltage test specified in 6.2 shall be applied for 1 min between the conductor and the
water. The test voltage shall be as specified in the cable specification. Immediately afterwards the
voltage shall be increased by 500 V every 30 s until a disruptive discharge occurs.
The recorded value shall exceed the specified minimum.
7 Ageing and thermal tests
7.1 Compatibility
Samples of completed cables shall be aged in accordance with the time and temperatures given in the
appropriate cable specification. The testing shall be in accordance with 8.1.4 of EN 60811-1-2 for
single layer. For multi-layered insulating systems special techniques are given in the particular cable
standard (see 4.4).
7.2 Long term ageing for insulation
7.2.1 General
This test method provides a standard test and procedure for determining the 20 000 h life versus
temperature curve for insulating materials.
NOTE  This method may also be used for certain sheathing materials when required by the particular cable specification.
A brief explanation of the significance and use of the test is given in Annex C.
7.2.2 Summary of test method
Three or four sets of test specimens of a given sample of insulated wire are exposed for selected
periods of time at several fixed temperatures. After each exposure period the specimen is wrapped on
a mandrel to simulate a flexing stress and then immersed in a water bath where it is subject to a
voltage test. A given specimen is subjected to a continued series of exposures at its designated test
temperature until failure occurs.
The life data at different temperatures are analysed on the basis of the Arrhenius equation which
relates exposure time to failure to the reciprocal of the absolute temperature of exposure. The method
is based on EN 60216-1.
7.2.3 Apparatus
The ageing shall be carried out in a circulating air oven, meeting the general requirements of 8.1.2 of
EN 60811-1-2 and capable of operating at the required temperature. The vertical internal dimension of
the oven shall be at least 500 mm.
A rack shall be provided for holding insulated wire specimens. A simple one can consist of 6 mm rods
located horizontally approximately 25 mm below the top of the chamber. These can be mounted as a
part of the chamber or as a removable rack carrying the specimens.

Stabilising weights, each with a hook, shall be provided for holding insulated wire specimens straight
in the oven during ageing. The appropriate weight size is about one-half of the wrapping test weight
shown in Table 4. It is suggested that this weight also has a hook on the bottom so that the additional
weight required for the mandrel wrap can be added without removing the stabilising weight.
7.2.4 Method
7.2.4.1 Test specimens
Each specimen shall be a 300 mm to 400 mm length of insulated wire whose insulation is free from
visible imperfections. It is convenient to strip approximately 6 mm of insulation at each end and apply a
lug from which the weights can be suspended. The lug shall be of a type that not only contacts the
conductor but also clamps the insulation to prevent shrinkage with temperature exposure.
7.2.4.2 Temperature selection and exposure
The selection of temperatures for test shall be achieved by adding 20 °C to the expected end-of-life
temperature for the lowest temperature and two further temperatures at 10 °C to 20 °C successive steps. If
the average life at the highest test temperature is found to be less than 100 h, too high a test temperature
has been selected and the data should be discarded. The test should be repeated at a lower temperature.
Extrapolation to a temperature should not exceed 25 °C below the lowest ageing test temperature. If
extrapolation beyond 25 °C is required, an additional series of tests shall be made at an even lower
temperature. If, in addition, the average life found at the lowest test temperature is less than 5 000 h,
tests shall be made at lower temperatures until at least 5 000 h average life data are achieved.
The average life of the specimen may be affected by the number of cycles; therefore to maintain a
consistency in the procedure that will ensure a reliable degree of reproducibility, make an effort to
expose each to an average of not less than eight cycles and not more than fifteen cycles. A first
estimate of cycle time is given in Table 3. This table provides a selection of the days per cycle and the
recommended ageing temperatures for cables having 20 000 h thermal endurance temperatures
ranging from 105 °C to 180 °C. This range could be extended easily if necessary. During the course of
the test, increase or decrease the length of the remaining cycles if necessary.
Make a quick estimate of the highest test temperature by running cycles of approximately one day in
length at 80 °C to 100 °C above the normal rating temperature of the cable or at a point just below the
melting point of the insulation if it is within this range.

– 17 – EN 50305:2002
Table 3 – Recommended exposure times in days per cycle
Ageing Duration of exposure in days for an
a
temperature estimated temperature value (°C) of:
°C 105 130 155 180
250 1
240 2
230 4
220 1 7
210 2 14
200 1 4 28
190 2 7 49
180 1 4 14
170 2 7 28
160 41449
150 7 28
140 14 49
130 28
120 49
a
Tolerances are given in Table 1.
Begin the test sequence with the highest temperatures, since exposure times will be relatively short. On the
basis of these results, review the proposed lower exposure temperatures and revise if necessary.
7.2.4.3 Wrapping procedure
After each period of exposure remove the group of specimens from the oven. Allow them to cool to
room temperature.
A mandrel shall be provided, supported horizontally, and fitted at one end with a crank for mandrel
wrapping of the specimens. Support the rod at least 600 mm above a horizontal work surface. The mandrel
shall be provided with some convenient means for attaching one end of the insulated wire for wrapping. A
suggested method of attachment is the crank arm shown in Figure 5. The diameter of the round mandrel
and weights for attaching to the lower end of the specimens during the mandrel wrap shall be as in Table 4.
Table 4 – Requirements for wrapping test
Conductor cross section Mandrel diameter Weight
mm mm kg
0,5 13 0,50
0,75 15 0,50
1,0 20 0,75
1,5 20 0,75
2,5 25 1,00
Key
1 Set screw 4 Test specimen
2 Lug type solderless terminal 5 Eyelet
3 Mandrel 6 Mass
Figure 5 – Suggested method of attachment of insulated wire test specimen to mandrel
Attach one end of the specimen to the mandrel. Hang the prescribed added weight to its lower end.
Rotate the mandrel so that the specimen is wrapped on it, first in one direction and then in the
opposite direction. Do this twice. During the wrapping allow the insulated wire to twist freely and seek
its own position on the mandrel with only the limitation that the core or cable must stay in contact with
the mandrel and not wind upon itself. The speed of winding shall be uniform at a rate of one turn in 3 s
to 5 s. It is preferable to have the winding motorised, but it may be done by hand. Then unwind the
specimen at the same rate, remove the weights and detach the specimen from the mandrel.
7.2.4.4 Voltage test
Connect the two ends of a specimen together and immerse the specimen at room temperature in a
bath containing 1 % of sodium chloride (NaCl) with 25 mm to 30 mm of each end of the insulated wire
above the surface. Soak for 1 h.
Subject the specimens to the voltage test as specified in 6.2. at 1,5 kV a.c. unless otherwise specified
in the product standard.
7.2.4.5 Continuation of exposure
A given specimen shall be subjected to a continued series of exposures at the designated test
temperature, including wrapping sequence and voltage test, until electrical failure occurs.

– 19 – EN 50305:2002
7.3 Long term ageing for sheath
Samples of sheath from cable shall be aged as in EN 60216-1, except that after each exposure time
three test pieces shall be tested for elongation at break in accordance with 9.2 of EN 60811-1-1 and
the mean value recorded. The method of treatment of the results shall be as given in EN 60216-1 in
which the exposed time to failure is based on a value of 50 % elongation at break.
7.4 Ozone resistance
7.4.1 Electrical test
The test sample shall be wound for at least 6 complete turns on to a cylindrical mandrel of diameter
(10 � 1,0) times the minimum diameter of the cable.
The assembly shall be subjected to ozone exposure as specified in the product specification. At the
conclusion of the exposure it shall be examined for cracks and then subjected to the voltage test as
specified in 6.2.
The examination and voltage test shall be carried out after cooling to ambient temperature and before
24 h have elapsed.
7.4.2 Non-electrical test
7.4.2.1 Test apparatus and testing devices
a) suitable ozone test chamber with uniform ozone concentration;
b) cutting device for preparation of test pieces;
c) clamping device according to Figure 6, or a similar device;
d) cylindrical mandrels consisting of wood or metal;
e) desiccator filled with silica gel or an equivalent material.
7.4.2.2 Selection and cutting of test pieces
Three test pieces of at least 200 mm length consisting of the complete core or cable shall be used
whenever possible under the proviso however that any coverings over the insulation or the sheath to be
tested have been removed, care being taken not to damage the insulation or the sheath.
If it is impossible to use the complete core or cable, the insulation or sheath respectively shall be cut
longitudinally and the required three test pieces of at least 5 mm but not more than 10 mm width shall be
punched by using the cutting device according to 7.4.2.1 b). The test pieces shall be ground or cut, so
as to obtain test pieces of uniform thickness, care being taken to avoid undue heating. After grinding or
cutting the thickness of test pieces shall be not less than 0,8 mm and not more than 2,0 mm.
7.4.2.3 Conditioning and preparation of test pieces
The test pieces shall be wiped with a clean cloth to remove dirt or moisture and stored in the desiccator
according to 7.4.2.1 e) for at least 16 h.
Test pieces consisting of the complete core or cable shall be wound around the mandrel according to
7.4.2.1 d). The diameter of the mandrel shall be (2 ± 0,
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