30101941 pdf BRITISH STANDARD BS EN 50395 2005 Electrical test methods for low voltage energy cables ICS 29 060 20 + A1 201 1 National foreword This British Standard is the UK implementation of EN 503[.]
Trang 1Electrical test methods
for low voltage energy
cables
ICS 29.060.20
Trang 2National foreword
This British Standard is the UK implementation of
EN 50395:2005+A1:2011 It supersedes BS EN 50395:2005, which is withdrawn
The start and finish of text introduced or altered by amendment is indicated in the text by tags Tags indicating changes to CENELEC text carry the number of the CENELEC amendment For example, text altered by CENELEC amendment A1 is indicated by !"
The UK participation in its preparation was entrusted by Technical Committee GEL/20, Electric cables, to Subcommittee GEL/20/17, Electric Cables - Low voltage
A list of organizations represented on this subcommittee can be obtained on request to its secretary
This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application
Compliance with a British Standard cannot confer immunity from legal obligations
This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 14 November 2005
© BSI 2011
ISBN 978 0 580 67085 5
Amendments/corrigenda issued since publication Date Comments
31 October 2011 Implementation of CENELEC amendment A1:2011
Trang 3NORME EUROPÉENNE
EUROPÄISCHE NORM
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
© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref No EN 50395:2005 E
ICS 29.060.20 Partly supersedes HD 21.2 S3:1997 + A1:2002 &
HD 22.2 S3:1997 + A1:2002 English version
Electrical test methods for low voltage energy cables
Méthodes d'essais électriques Elektrische Prüfverfahren
für Niederspannungskabel und -leitungen
This European Standard was approved by CENELEC on 2005-07-01 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom
March 2011
Trang 4This European Standard was prepared by the Technical Committee CENELEC TC 20, Electric cables
In accordance with the decision of TC 20 at its Setubal meeting (June 2004), the text of the draft was submitted to the formal vote It was approved by CENELEC as EN 50395 on 2005-07-01
This European Standard, together with EN 50396:2005, supersedes HD 21.2 S3:1997 + A1:2002 and
HD 22.2 S3:1997 + A1:2002
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) 2006-07-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-07-01
Foreword to amendment A1
This amendment was prepared by the Technical Committee CENELEC TC 20, Electric cables
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as amendment A1 to EN 50395:2005 on 2011-03-14
The following dates were fixed:
– latest date by which the amendment has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2012-03-14
– latest date by which the national standards conflicting
with the amendment have to be withdrawn (dow) 2014-03-14
Trang 5
Page
Introduction 5
1 Scope 5
2 Normative references 5
3 General requirements 6
3.1 Pre-conditioning 6
3.2 Test temperature 6
3.3 Test voltage 6
3.4 Test values 6
4 Definitions 6
5 Electrical d.c resistance of conductor 6
6 Voltage test on completed cable 6
7 Voltage test on cores in water 7
7.1 Test sample 7
7.2 Procedure 7
7.3 Requirement 7
8 Insulation resistance test 7
8.1 Insulation resistance for cables having maximum conductor temperatures not exceeding 90 °C 7
8.1.1 Test sample 7
8.1.2 Procedure 8
8.1.3 Requirement 8
8.2 Insulation resistance for cables with maximum conductor temperatures exceeding 90 °C 8
8.2.1 Test sample 8
8.2.2 Procedure 8
8.2.3 Requirement 8
9 Long term resistance of insulation to d.c 9
9.1 Test sample 9
9.2 Procedure 9
9.3 Requirement 10
10 Check for the absence of faults in insulation 10
10.1 General 10
10.2 Spark test 10
10.2.1 Procedure 10
10.2.2 Requirement 10
10.3 Voltage test 10
10.3.1 Procedure 10
Trang 610.3.2 Requirement 10
11 Surface resistance of sheath 11
11.1 Test samples 11
11.2 Procedure 11
11.3 Requirement 11
12 Transfer impedance 11
Annex A 12
A.1 Basic formula 12
A.2 Rounding 12
A.3 Examples of calculation 12
Annex B (informative) Source of electrical test methods in EN 50395 13
Bibliography 14
Figure 1 – Positioning of electrodes 9
Trang 7EN 50395 contains the electrical test methods that are used for harmonized low voltage energy cables These electrical test methods include all those previously contained in HD 21 and HD 22 Annex B gives a comparison between the original location of each test method and its place in this new European Standard
The content of EN 50395 is not, and will not be, restricted only to test methods for cables to HD 21 and HD 22 Other test methods for harmonized LV cables may be included Furthermore, the use of test methods in EN 50395 for cables outside HD 21 and HD 22 is not prohibited, but it is strongly recommended that expert advice be taken before such use, or before any proposal for incorporation into another standard
1 Scope
EN 50395 contains electrical test methods required for the testing of harmonized low voltage energy cables, especially those rated at up to and including 450/750 V
NOTE 1 A description of the origin of these test methods and the background to this European Standard is given in the Introduction and in Annex B.
The particular cable standard dictates the tests which need to be performed on the relevant cable type It also specifies whether the specific test is a type test (T), a sample test (S) or a routine test (R) for the particular cable type
NOTE 2 T, S and R are defined in the relevant cable standard.
The requirements to be met during or after the test are specified for the particular cable type in the relevant cable standard However, some test requirements are obvious and universal, such as the fact that no breakdown shall occur during voltage tests, and these are stated in the particular test method Test methods for use specifically in utility power cables are not covered by this European Standard They can be found in HD 605
Test methods for use specifically in communications cables are the responsibility of the Technical Committee CENELEC TC 46X, Communication cables At present such test methods are given in
EN 50289 series
2 Normative references
The following referenced documents are indispensable for the application of this document For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies
EN 50289-1-6 2002 Communication cables – Specifications for test methods
-Part 1-6: Electrical test methods – Electromagnetic performance
EN 60228 2005 Conductors of insulated cables
EN 62230 2007 Electric cables – Spark test method
Trang 83 General requirements
3.1 Pre-conditioning
All 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
3.2 Test temperature
Unless otherwise specified, tests shall be made at an ambient temperature of (20 ± 15) °C
3.3 Test voltage
Unless otherwise specified in the individual clause of this European Standard or in the product standard, the test voltage shall be a.c of approximately sine-wave form and of frequency between
49 Hz and 61 Hz The ratio of peak value to r.m.s value shall be equal to √2 with a tolerance of ± 7 % The values quoted are r.m.s values
3.4 Test values
Full test conditions (such as temperatures, durations, etc.) and full test requirements are not specified
in this European Standard; it is intended that they should be specified by the standard dealing with the relevant type of cable
Any test requirements which are given in this European Standard may be modified by the relevant cable standard to suit the needs of a particular type of cable
4 Definitions
For the purposes of this document, the following terms and definitions apply
4.1
median value
when several test results have been obtained and ordered in an increasing or decreasing succession, the median value is the middle value if the number of available values is odd, and is the mean of the two middle values if the number is even
5 Electrical d.c resistance of conductor
The test shall be carried out in accordance with Annex A of EN 60228
6 Voltage test on completed cable
If the cable has no metallic layer, a sample of the cable as manufactured shall be immersed in water The length of the sample, the temperature of the water and the period of immersion shall be as specified in the cable standard A voltage shall be applied between conductor(s) and groups of conductors in such a way that the insulation on each core is tested against all adjacent cores and the water
Trang 9If the cable has a metallic layer, a sample of the cable shall be taken of the length specified in the cable standard A voltage shall be applied between conductor(s) and groups of conductors in such a way that the insulation on each core is tested against all adjacent cores and the metallic layer, which shall be earthed
If the cable has a metallic strain-bearing member, this shall be connected to the water or to the metallic layer, as appropriate
In each case, the voltage and the duration of its application shall be as specified in the cable standard The voltage shall be increased gradually on each occasion to the specified value
No breakdown of the insulation shall occur during the test
7 Voltage test on cores in water
The test applies to sheathed cables, braided cables and flat unsheathed cords
NOTE For 1-core unsheathed cables, the test in Clause 6 generally applies, in which case this test on cores is not required.
7.1 Test sample
Prepare a sample of cable 5 m long, by carefully removing, without damaging the cores, the sheath or the overall braid and any other covering or filling from a length of completed cable
In the case of flat unsheathed cord, make a cut in the insulation between the cores, and separate the cores by hand for a length of 2 m
7.2 Procedure
Immerse the sample in water at the temperature, and for the period, specified in the cable standard Ensure that the ends of the cores protrude above the water by a distance sufficient to prevent excessive surface leakage when the test voltage is applied Apply a voltage, of the magnitude specified in the cable standard, between the conductors and the water for the time specified in the cable standard
7.3 Requirement
No breakdown of the insulation shall occur during the test
8 Insulation resistance test
8.1 Insulation resistance for cables having maximum conductor temperatures not exceeding 90 ¡C
8.1.1 Test sample
Make the test on a sample of cable 5 m long, previously submitted to the test specified in Clause 7 or,
in the case of 1-core unsheathed cable, to the test described in Clause 6
Trang 108.1.2 Procedure
Immerse the sample in water previously heated to the temperature specified in the cable standard, with a length of about 250 mm at each end of the sample projecting above the water, for the period of time specified in the cable standard
Apply a d.c voltage of between 80 V and 500 V between each conductor and the water
Measure the insulation resistance of each core 1 min after application of the voltage Use this value to calculate the insulation resistance of a 1 km length of each core
8.1.3 Requirement
None of the resulting values shall be below the minimum insulation resistance value specified in the cable standard
8.2 Insulation resistance for cables with maximum conductor temperatures
exceeding 90 ¡C
NOTE Further basic information on this test method may be obtained from HD 429, Clause 6 “Test pieces for the volume resistivity measurement”.
8.2.1 Test sample
Make the test on the same sample of cable used for the voltage test in Clause 7 or, in the case of 1-core unsheathed cable, to the test described in Clause 6
8.2.2 Procedure
Cut a test piece 1,40 m long from the cable or core to be tested Cover this test piece with a semi-conducting layer, and over this layer apply a metal braid or a metal tape in such a way as to obtain an active measuring length of 1,0 m
At both ends of the active measuring length, leaving a gap 1 mm wide, apply a protective wire binding
of approximately 5 mm length (see Figure 1)
Wind the test piece to form a ring with a diameter of approximately 15D but at least 0,20 m (D = nominal outer diameter of insulation).
Maintain the test piece in an air oven for at least 2 h at the test temperature specified in the relevant cable standard, leaving a clearance between the sample and the walls of the air oven of at least
50 mm
After the conditioning period a d.c voltage between 80 V and 500 V shall be applied between the conductor and the screen (semi-conducting layer and metal braid/metal tape including the protective wire binding), the sample still being kept in the air oven
The insulation resistance shall be measured 1 min after application of the voltage and this value shall
be used to calculate the insulation resistance of a 1 km length of cable
8.2.3 Requirement
None of the resulting values shall be below the minimum insulation resistance value specified in the cable standard
NOTE Annex A shows the calculation method for minimum insulation resistance.
Trang 111 guard electrode (protective wire binding) 2 screen electrode
Figure 1 —Positioning of electrodes
9 Long term resistance of insulation to d.c.
9.1 Test sample
Carry out the test on a sample of cable of 5 m length from which all coverings have been removed The cores of flat unsheathed cords shall not be separated
For cables having up to five cores, each core shall be tested For multicore cables having more than five cores, one core of each colour in the cable shall be tested, and where the number of colours is less than 5, duplicate coloured cores shall be tested as necessary to bring the number of cores tested
up to a minimum of 5
Take care to avoid damage to the core(s) during removal of the coverings
9.2 Procedure
Immerse the sample, for the period and at the temperature given in the relevant cable standard, in an aqueous solution of sodium chloride having a concentration of 10 g/l, with a length of about 250 mm at each end of the sample projecting above the solution Connect the negative pole of a 220 V d.c supply to the conductor(s) of the sample and the positive pole to a copper electrode immersed in the solution for the time given in the relevant cable standard