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UDC: 629.13.01 :621.315 : .001.4 Ref. No.: ISO/R 634 - 1967 (E)
IS0
I N T E R NAT1 O NAL OR GAN I ZATl O N FOR STAN DARD I ZATl ON
I S O R E C O M M E N D AT1 O N
R 634
METHODS OF TEST
FOR GENERAL PURPOSE ELECTRICAL CABLES
WITH COPPER CONDUCTORS FOR AIRCRAFT
1st EDITION
November 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 634, Methods of Test for General Purpose Electrical Cables
with Copper Conductors for Aircraft, was drawn up by Technical Committee ISO/TC 20, Aircraft,
the Secretariat of which is held by the British Standards Institution (BSI).
Work on this question by the Technical Committee began in 1960 and led, in 1962, to the
adoption of a Draft IS0 Recommendation.
In May 1965, this Draft IS0 Recommendation (No. 807) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies :
Argentina Israel Switzerland
Belgium Italy U.A.R.
Brazil Japan United Kingdom
Canada Netherlands Yugoslavia
Chile Portugal
Czechoslovakia Republic
France of South Africa
Germany Spain
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in November 1967, to accept it as an IS0 RECOMMENDATION.
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CONTENTS
Page
1 . Scope .
5
I . Type tests only .
5
2 . Resistance to typical aircraft fluids . 5
3 . Ageing in air at high temperature. followed by a bend test at room temperature and
an insulation test while immersed in water .
4 . Flexibility test at room temperature .
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5 . Bend test at low temperature .
6 . Surface creepage test whilst immersed in salt water .
7 . Heat test .
8 . Test for emission of smoke .
9 . Test of physical properties of insulation material .
10 . Abrasion test .
II . Type and production routine tests .
9
11 . Conductor resistance tests .
9
12 . Insulation tests .
9
III . Type and production quality tests .
9
13 . Flammability tests . 9
14 . Tensile and elongation tests on conductors . 9
15 . Tinning tests on conductors . 9
16 . Test of physical properties of insulation material .
10
Annex A : Preparation of the test pieces for elongation at break test .
11
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Annex B : Abrasion testing machine . 12
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ISO/R 634 - 1967 (E)
IS0 Recommendation R 634 November 1967
METHODS OF TEST
FOR GENERAL PURPOSE ELECTRICAL CABLES
WITH COPPER CONDUCTORS FOR AIRCRAFT
1. SCOPE
This IS0 Recommendation describes the tests suitable for establishing the compliance of general
purpose electrical cables with copper conductors for aircraft with the performance requirements
stated in IS0 Recommendation R 474, Performance Requirements for General Purpose Electrical
Cables with Copper Conductors for Aircraft. They are intended for use as a basis for specifying
tests in the relevant national specifications where the national type approving authorities consider
that existing tests are inadequate.
The tests are classified as follows :
I. Type tests only,
II. Type and production routine tests,
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III. Type and production quality tests.
I. TYPE TESTS ONLY
2. RESISTANCE TO TYPICAL AIRCRAFT FLUIDS
The object of this test is to check that the cable will not be affected in such a way as to cause
2.1
failure in service or undue difficulties in servicing by any of the fluids with which it is likely
to come into contact on modern aircraft.
2.2 Separate cable samples should be bent into a loop of a diameter approximately fourteen times
the overall diameter of the cable and immersed each in one of the following fluids, with the
ends clear of the fluid, for not less than 20 hours, at a temperature such as is likely to be
experienced in service for the particular fluid:
(U) Aviation fuels;
(b) Lubricating oils (including ester-based oils) ;
(c) Hydraulic fluids (including ester-based hydraulic fluids) ;
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(d) De-icing fluids.
2.3 After immersion, the samples should be wiped, straightened and cooled to a temperature
of 20 f 5 OC, and then subjected to a bend of 360" round a mandrel having a diameter of not
more than fourteen times the overall diameter of the cable. After this treatment, the dia-
meter of the cable should not have increased by more than 5 %. There should be no cracking,
splitting or other deterioration of the outer coverings and the samples should withstand a
voltage test of 1500 V r.m.s. and a frequency at any value from 25 to 100 Hz inclusive, for
at least 1 minute without breakdown in water.
3. AGEING IN AIR AT HIGH TEMPERATURE,
FOLLOWED BY A BEND TEST AT ROOM TEMPERATURE
AND AN INSULATION TEST WHILE IMMERSED IN WATER
The object of this test is to check that there is no cracking of the outer coverings of the cable
3.1
during bending after heating and that the cable will not break down electrically due to
displacement of the conductor resulting from deformation of the insulation at high tempe-
rature with the conductor under a tensile load. In addition, the test is designed to check that
there is no deterioration of the conductor surface as a result of the insulation having been
aged at a high temperature.
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ISO/R 634 - 1967 (E)
3.2 Air oven
A test piece of cable at least 24 in (61 cm) long, having the insulation removed for 1 in
(25 mm) at each end, should be bent at least 180" round a cylindrical mandrel of diameter
as specified in Table 1. The conductor should be loaded in such a manner that the portion
of the insulation compound between the conductor and the mandrel is under compression
while the conductor has attached at each end the load specified in Table 1. These conditions
should be maintained for a period of 120 hours in an air oven at a constant temperature of
120 f 2 OC. On removal from the air oven, the test piece should be cooled to between 20
and 25 "C within a period of 1 hour. When cooled, the cable should be fr:ed from the load,
removed from the mandrel and straightened. The test piece should then be subjected suc-
cessively to the tests mentioned in clauses 3.3 and 3.4, and subsequently the insulation should
be removed from the test piece and the conductor examined. It should show no signs of
corrosion.
TABLE 1. - Diameters of mandrels and test loads for bend tests
Cable Maximum diameter of mandrel Test load
I
Nominal conductor Cable Bend test at Bend test at
Bend test * Bend test *
area I size
low temperature * 4 low temperature * 4
--
in2
in mm lbf daN 1 lbf daN
0.000 598
0.38 22 4.5 115 3 76 0.75 O. 3 2 0.9
o.Oo0 93 0.60 20 4.5 115 3 76 0.75 0.3 2 0.9
0.001 47 0.95 18 4.5 115 3 76 1 .O 0.4 2 0.9
0.001 89 1.22 16 6.5 165 3 76 1 .O 0.4 3 1.4
0.003 O1 1.94 14 6.5 165 152 3
6 1 .O 0.4 1.4
0.004 77 3.08 12 6.5 165 6 152 3.0 1.4 3 1.4
0.008 2
5.29 10 10 254 6 152 3.0 1.4 5 2.3
0.013 3 8.55 8 10 6 152 5
254 3.0 1.4 2.3
0.021 1 13.6 6 10 254 10 254 6.0 2.7 10 4.5
0.033 5 21.6 4 10 254 10 254 6.0 2.7 10 4.5
0.052 6 33.9 2 10 254 18 457 6.0 2.7 15 6.8
0.064 3 41.5 1 10 254 18 457 6.0 2.7 15 6.8
0.081 8 52.8 O 10 254 18 457 10.0 4.5 20 9.0
O. 105 68 00 10 254 18 457 10.0 11.3
4.5 25
0.132 85 O00 10 254 18 457 10.0 4.5 30 13.6
0.166
107 oooo 10 254 18 457 10.0 4.5 30 13.6
3.3 Bend test at room temperature
At a temperature maintained beiween 20 and 25 "C one end of the test piece should be
secured to the mandrel and the other end to the load specified in Table 1. The mandrel
should be rotated until the full length of the test piece is wrapped round the mandrel and is
under the specified tensile load with adjoining turns in contact with each other. The mandrel
should then be rotated in the reverse direction until the full length of the surface of the
cable which was outside during the first wrapping is now next to the mandrel. This proce-
dure should be repeated until two bends in each direction have been formed in the same
section of the cable. There should be no cracking or puckering of the outer coverings of
the finished cable as a result of this test.
3.4 Insulation test in water
The uninsulated ends of the test piece should be fastened in metallic contact to a metal bar.
Care should be taken to avoid fraying the ends of the insulation and protective covering.
The distance between the two uninsulated ends of the cable should be equal to the diameter
of the mandrel specified in Table 1. The test piece should be immersed in a 5 % aqueous
sodium chloride solution at a temperature of 20 to 25 "C so that the insulation and protective
covering protrudes 1% in (38 mm) from the surface of the liquid. After immersion for
* See clauses 3.2 and 3.3.
** See clause 5.3, method B.
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ISO/R 634 - 1967 (E)
5 hours, a potential with a voltage of 1500 V r.m.s. and a frequency at any value from 25 to
100 Hz inclusive should be applied between the conductor and an electrode in contact with
the liquid. This voltage should be increased at a uniform rate from O to 1500 V within 30
seconds and maintained at 1500 V for a period of 5 minutes without breakdown.
4. FLEXIBILITY TEST AT ROOM TEMPERATURE
4.1 The purpose of this test is to check that none of the constituent parts of the cable will crack
during the flexing which is likely to be experienced during installation or service.
4.2 Before submission to the following test the cable should be maintained for a period in air
at a temperature of 20 i 5 OC and a relative humidity of 75 %.
4.3 The test piece of the complete cable should be wound on a mandrel into a close helix of at
least three complete turns at a temperature of 20 f 5 "C under a tensile load of such a
value as to ensure that the cable conforms to the mandrel. The mandrel diameter should not
be more than three times the maximum specified overall diameter of the cable for cables
having overall diameters up to 0.48 in (12.2 mm) and six times the maximum specified over-
all diameter of cable for larger cables.
4.4 The complete test should comprise five test cycles, each cycle consisting of the winding of
so that the sur-
the cable on the mandrel, unwinding and rewinding in the reverse direction
face of the cable inside the helix during the first winding is on the outside of the helix on
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rewinding.
4.5 After this treatment no part of the cable should show signs of damage likely to affect the
performance of the cable in service. The test pieces should then be subjected to a voltage
test of 1500 V r.m.s. and a frequency at any value from 25 to 100 Hz inclusive, for at least
1 minute without breakdown in water.
5. BEND TEST AT LOW TEMPERATURE
5.1 The purpose of this test is to check that no constituent parts of the cable will crack under
conditions of severe flexing at temperatures down to -30 OC. The test is not necessarily
applicable to cables having an overall diameter of 0.345 in (8.8 mm) or larger.
5.2 Before submission to the test, thecable should bemaintained fora period inair at a temperature
of 20 & 5 "C and a relative humidity of 75 %. The mandrels used in the test should be of
metal and should be allowed to cool to the specified temperature with the cable.
5.3 Acceptable alternative methods of test are as follows:
Method A
(U) A test piece of the cable at least 12 in (30 cm) long should be stored in air at a tempera-
L ture of -30 f 2 OC for a period of 6 hours, immediately after which it should be wound
on a mandrel. The diameter of the mandrel should be ten times the maximum specified
diameter of the cable. The rate of bending should be uniform at one complete turn each
second. A re
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