1、BSI Standards PublicationBS EN 3475-307:2015Aerospace series Cables,electrical, aircraft use TestmethodsPart 307: Corona extinction voltageBS EN 3475-307:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 3475-307:2015. It supersedes BS EN 3475-307:2010 which
2、is withdrawn.The UK participation in its preparation was entrusted to Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all
3、the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 86107 9ICS 49.060Compliance with a British Standard cannot confer immunity from legal obligations.This British Stand
4、ard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 3475-307 June 2015 ICS 49.060 Supersedes EN 3475-307:2010English Version
5、 Aerospace series - Cables, electrical, aircraft use - Test methods - Part 307: Corona extinction voltage Srie arospatiale - Cbles lectriques usage aronautique - Mthodes dessais - Partie 307: Tension dextinction corona Luft- und Raumfahrt - Elektrische Leitungen fr Luftfahrtverwendung - Prfverfahren
6、 - Teil 307: Corona-Aussetzspannung This European Standard was approved by CEN on 21 June 2014. CEN 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-d
7、ate lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translatio
8、n under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Fo
9、rmer Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMI
10、T EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 3475-307:2015 EBS EN 3475-307:2015EN 3475-307:2015 (E)
11、2 Contents Page European Foreword 3 1 Scope 5 2 Normative references 5 3 Terms and definitions .5 4 Applicability 5 5 Apparatus .6 6 Methods 6 6.1 General 6 6.2 Method A .6 6.3 Method B .7 7 Procedure .8 8 Requirement .9 BS EN 3475-307:2015EN 3475-307:2015 (E) 3 European Foreword This document (EN 3
12、475-307:2015) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has received the approval of the National Associations and the Official Se
13、rvices of the member countries of ASD, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2015, and conflicting national standards shall be withdrawn at the
14、 latest by December 2015. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 3475-307:2010. According to the
15、CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hun
16、gary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 3475-307:2015EN 3475-307:2015 (E) 4 Introduction For an electrical cable, the presence of partial
17、discharges effects at operating voltage may result in a significant reduction of service life. Some insulation materials are more susceptible to such discharge damage than others. Evidence of partial discharges during operation signifies for example: the insulation thickness is insufficient for the
18、applied voltage; the quality of the insulation is inadequate possibly due to excessive size or quantities of internal cavities or voids; an overstress is present, resulting in a local reduction of the cable insulation properties. Significant parameters may influence PDIV *and PDEV *such as pressure,
19、 temperature, humidity, previous electrification, input signal characteristics (sine wave, voltage rate, .). Attention shall be given to installation conditions in A/C, for example excessive bending or surface wrinkling of insulation shall be avoided. Up to few tens of kHz frequency can be considere
20、d as non-significant parameter. *See definition, Clause 3. BS EN 3475-307:2015EN 3475-307:2015 (E) 5 1 Scope This European Standard defines methods to cover the detection and measurement of partial discharge (corona) under an applied test voltage, including the determination of partial discharges (c
21、orona) inception and extinction voltages as the test voltage is raised and lowered, of electrical cables for aircraft use. It shall be used together with EN 3475-100. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensabl
22、e for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 2235, Aerospace series Single and multicore electrical cables, screened and jacketed EN 3475-100, Aerospace series
23、 Cables, electrical, aircraft use Test methods Part 100: General EN 60270, High-voltage test techniques Partial discharge measurements ASTM D 1868, Standard Test method for Detection and Measurement of Partial Discharge (Corona) Pulses in Evaluation of Insulation Systems 1)3 Terms and definitions Fo
24、r the purposes of this document, the following terms and definitions apply. 3.1 Partial Discharge Inception Voltage PDIV lowest voltage at which continuous (Steady state with a minimum of 1 detected Partial Discharge per second for 10 s minimum) partial discharges occur as the applied voltage is inc
25、reased 3.2 Partial Discharge Extinction Voltage PDEV highest voltage at which partial discharges no longer occur as the applied voltage is decreased from the inception voltage described before NOTE 1 to entry More precise information on the partial discharge phenomenon, such as definition, can be fo
26、und in ASTM D 1868-07 or in EN 60270. 4 Applicability This test method is suitable for coaxial cables, high voltage cables and for thin wall insulated cables. Methodologies are proposed to cover: coaxial cables (Method A), wires used in altitude (Method B). 1) Published by: ASTM National (US) Americ
27、an Society for Testing and Materials http:/www.astm.org/.BS EN 3475-307:2015EN 3475-307:2015 (E) 6 5 Apparatus The equipment shall be capable of detecting partial discharges of five picocoulombs or less. The detection equipment, cautions and measurement procedures shall be equivalent to those descri
28、bed in ASTM D 1868 or in EN 60270. The frequency of the test voltage shall be between 48 Hz to 62 Hz. 6 Methods 6.1 General Two methods are proposed according to specific needs. Unless otherwise specified in the concerned product standard Method A applies. The minimum specimen length shall be chosen
29、 so that its capacitance is matched to the needs of the detecting equipment to permit observation of discharges of the level described in Clause 5. Use ASTM D 1868 for guidance to determine this length. In any case the minimum length under test shall not be less than 850 mm. It is particularly impor
30、tant that the ends of specimen to test and that the test bench are corona free. WARNING Lethal voltage may be present during this test. It is essential that procedures and test apparatus are properly defined and used for safe operation. 6.2 Method A 6.2.1 Case of use This method is particularly dedi
31、cated to measure PDEV of coaxial cables, under ambient conditions. 6.2.2 Specimen preparation A suggested method for making the ends corona free is shown on Figure 1 to Figure 3. Step 1: If compatible with Clause 6 above, suggested length of cable specimen is 1 m. Step 2: Remove 75 mm of the jacket
32、material from each end. Dimensions in millimetres Figure 1 BS EN 3475-307:2015EN 3475-307:2015 (E) 7 Step 3: Roll back the braid over the jacket and trim as shown. Be careful to avoid breaking any strands. Trim the braid edges nearly to 25 mm lengths. Dimensions in millimetres Figure 2 Step 4: Trim
33、one end of the specimen to the dimensions shown and cover the braid edge and jacket with a plastic tube or adhesive tape or heat-shrink sleeve as shown. On the other end, wrap a gauge 20 coated copper grounding wire tightly over the braid or use an equivalent grounding method. Dimensions in millimet
34、res Figure 3 6.3 Method B 6.3.1 Case of use This method is particularly dedicated to single wires, without screen, used in altitude (low pressure) in non-pressurized areas under particular temperature conditions. 6.3.2 Specimen preparation Specimens must be prepared as described in 6.2.2, with the a
35、ddition of a braid, as close as possible to the wire insulation without any risk of superficial damage. Strip the two ends. Add a braid on the whole cable length as per EN 2235. Step 1: position the braid so that about 75 mm (depends of test bench) are not shielded on both sides so that no partial d
36、ischarges are created between specimen and test bench. Step 2: bend the cable so that the bending radius is for four times the cable diameter. Maintaining of the loop shall not be source of crushing nor twisting. See Figure 4. Step 3: use heat shrinkable sleeves (or equivalent) on both extremities t
37、o stop the braid and avoid any partial discharge generation at this level. BS EN 3475-307:2015EN 3475-307:2015 (E) 8 Step 4: join extremities of the braid, twist them, and join them to the extremity of the grounding method NOTE Temperature acceptable by additional materials shall be compatible with
38、temperature called for this test by the concerned product standard. Measurements shall be made between joined ends of the wire and the end of the grounding method. Then each specimen shall be put in a vacuum chamber where required pressure and temperature can be obtained. Figure 4 7 Procedure Before
39、 connecting the cable test specimen to a voltage source, using the selected connection devices, calibrate and measure the maximal PDIV of the bench test. This value shall be far beyond (around three times) the cable test specimen PDIV value. After cable preparation, connect the test specimen to the
40、voltage source. For methods A, both ends may be immersed in insulating oil to prevent corona discharge at the ends. For method B, the use of sharp gripping devices such as alligator chips is forbidden. Generally PDIV and PDEV tests shall be performed at room ambient conditions (Method A), except whe
41、n specified in the concerned product standard with a specified altitude or equivalent reduced pressure and temperature (Method B). 1) Increase the test voltage from 0 to the minimum value giving PDIV (see definition 3.1). Record the value. 2) Decrease the voltage till PDEV occurs. Record the value.
42、3) Then Set the test voltage to 0. 75mm min. BS EN 3475-307:2015EN 3475-307:2015 (E) 9 4) Repeat 3 times this sequence from 1) to 3). NOTE A first rise of voltage is necessary to activate the electron form (important to engage the phenomenon of partial discharges), which occurs at a voltage level hi
43、gher than PDIV. The cable test specimen shall be subjected to gradually increasing sinusoidal voltage until the detector indicates a sustained corona discharge. Take the value of the PDIV when the partial discharges are continuous during more than one second. If sustained corona discharge PDIV is in
44、dicated, the voltage shall then be decreased slowly until the corona extinction point PDEV is observed. The corona extinction voltage PDEV is defined as the voltage at which sustained discharge ceases. If sustained partial discharges have not been observed at two times the specified partial discharg
45、es extinction level PDIV, the requirement is considered to have been satisfied. Unless otherwise specified in the concerned product standard, at least three different specimens shall be tested. 8 Requirement When required, PDEV and/or PDIV shall be within the limits indicated in the product standard
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