1、ASD STANDARD NORME ASD ASD NORM prEN 3475-307 Edition P 2 June 2009 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATIONAvenue de Tervuren, 270 - B-1150 Brussels - Tel. + 32 2 775 8126 - Fax. + 32 2 775 8131 - www.asd-stan.orgICS: 49.060 Supersedes edition P 1 of
2、 March 2002 and will supersede EN 3475-307:2005 Descriptors: ENGLISH VERSION 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 Raumfa
3、hrt Elektrische Leitungen fr Luftfahrtverwendung Prfverfahren Teil 307: Corona-Aussetzspannung This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for the needs of t
4、he European Aerospace Industry. It has been technically approved by the experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionall
5、y, without re-identification of the standard. After examination and review by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN na
6、tional members have then to implement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 10 June 2009 Comments should be sent within six months after the date of publication t
7、o ASD-STAN Electrical Domain Copyright 2009 by ASD-STAN Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 3475-307:20092 Contents Page Foreword2 Introduction .3 1 Scope 3 2 Normative references 3 3 Abbr
8、eviations and definitions 4 4 Applicability4 5 Apparatus .4 6 Methods 4 7 Procedure .7 8 Requirement.8 Foreword This standard was reviewed by the Domain Technical Coordinator of ASD-STANs Electrical Domain. After inquiries and votes carried out in accordance with the rules of ASD-STAN defined in ASD
9、-STANs General Process Manual, this standard has received approval for Publication. Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 3475-307:2009 3 Introduction For an electrical cable, the presence o
10、f partial 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 insufficien
11、t for the applied voltage; the quality of the insulation is inadequate possibly due to excessive size 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, tempe
12、rature, humidity, previous electrification, rate of the voltage increase. Attention shall be given to installation conditions, for example excessive bending or surface wrinkling of insulation shall be avoided. Up to few tens of kHz frequency can be considered as non-significant parameter. 1 Scope Th
13、is test standard defines methods to cover the detection and measurement of partial discharge (corona) under an applied test voltage, including the determination of partial discharges (corona) inception and extinction voltages as the test voltage is raised and lowered, of electrical cables for aircra
14、ft use. It shall be used together with EN 3475-100. 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
15、 any amendments) applies. EN 2084, Aerospace series Cables, electric, single-core, general purpose, with conductors in copper or copper alloy Technical specification. EN 2235, Aerospace series Single and multicore electrical cables, screened and jacketed. EN 3475-100, Aerospace series Cables, electr
16、ical, 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)1) Published by: American Society for
17、Testing and Materials (ASTM), 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 USA. Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 3475-307:20094 3 Terms and definitions For the p
18、urposes of this document, the following terms and definitions apply. 3.1 partial discharge inception voltage (PDIV) is the lowest voltage at which continuous partial discharges occur as the applied voltage is increased 3.2 partial discharge extinction voltage (PDEV) is the highest voltage at which p
19、artial discharges no longer occur as the applied voltage is decreased from the inception voltage described before More precise information on the partial discharge phenomenon, such as definition, can be found in ASTM D 1868-07 or in EN 60270. 4 Applicability This test method is suitable for coaxial
20、cables, high voltage cables and for thin wall insulated cables. Three methodologies are proposed to cover: coaxial cables (Method A), wires used in altitude (Method B) and wires in ambient conditions (Method C). 5 Apparatus The equipment shall be capable of detecting partial discharges of five picoc
21、oulombs or less. The detection equipment, cautions and measurement procedures shall be equivalent to those described 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 Three methods are proposed according to specific needs. Unless
22、otherwise specified in the concerned product standard Method A applies. The minimum specimen length shall be chosen 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 deter
23、mine this length. In any case the minimum length under test shall not be less than 850 mm. It is particularly important that the ends of specimen to test shall be made corona free. WARNING Lethal voltage may be present during this test. It is essential that procedures and test apparatus be properly
24、defined and used for safe operation. Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 3475-307:2009 5 6.2 Method A 6.2.1 Case of use This method is particularly dedicated to measure PDEV of coaxial cab
25、les, 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 material from each end. Figure 1 Ste
26、p 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. 752525 75Figure 2 Step 4: Trim one end of the specimen to the dimensions shown and cover the braid edge and jacket with a plastic tube or adhesive tape
27、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. 7570 12 150638Figure 3 Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted withou
28、t license from IHS-,-,-prEN 3475-307:20096 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
29、described in 6.2.2, with the addition of a braid, as close as possible to the wire insulation without any risk of superficial damage. Strip the two ends. NOTE Temperature acceptable by additional materials shall be compatible with temperature called for this test by the concerned product standard. F
30、orm one minimum loop with a diameter corresponding to the minimum bend radius specified for each gauge in its concerned technical specification (for example: Table 4 of EN 2084); see Figure 4. Maintaining of the loop shall not be source of crushing. Measurements shall be made between joined ends of
31、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 6.4 Method C 6.4.1 Case of use This method is particularly dedicated to single wire or assembly, with or without screen, for tests under
32、 ambient conditions. Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 3475-307:2009 7 6.4.2 Specimen preparation 6.4.2.1 Single wire Specimens shall be prepared as described in 6.2.2, with the addition
33、 of a braid, as close as possible to the wire insulation without any risk of superficial damage. Strip the two ends. Form one minimum loop with a diameter corresponding to the minimum bend radius specified for each gauge in its concerned technical specification (for example: Table 4 of EN 2084); see
34、 Figure 4. Maintaining of the loop shall not be source of crushing. Measurements shall be made between joined ends of the wire and the end of the grounding method. 6.4.2.2 Assembly Strip all ends. Unless otherwise specified in product standard, form one minimum loop with a diameter corresponding to
35、the minimum bend radius specified for each gauge in its concerned technical specification (for example: Table 4 of EN 2084). Maintaining of the loop shall not be source of crushing. Measurements shall be made between joined ends of each wire and all others extremities joined together. Particular car
36、e shall be taken to ensure a minimum separation distance of 70 mm between the two ends. 6.4.2.3 Shielded jacketed Specimens must be prepared as described in 6.2.2. Strip all ends. Unless otherwise specified in product standard, form one minimum loop with a diameter corresponding to the minimum bend
37、radius specified for each gauge in its concerned technical specification (for example: Table 4 of EN 2235). Maintaining of the loop shall not be source of crushing. Measurements shall be made between: a) joined extremities of all wire(s) and the extremity of the grounding method; b) joined ends of e
38、ach wire and all others ends joined together. Screen being in the air. Particular care shall be taken to ensure a minimum separation distance of 70 mm between all ends. 7 Procedure Before to connect the cable test specimen to a voltage source, using the retained connecting devices make the measureme
39、nt of the maximal PDIV of the bench test. This value shall be far beyond (around 3 times) the cable test specimen PDIV value. After the cable preparation, connect the cable test specimen to a voltage source. For methods A and C, both ends may be immersed in insulating oil to prevent corona discharge
40、 at the ends. For method B, the use of sharp gripping devices such as crocodile pliers is forbidden. Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 3475-307:20098 Generally PDIV and PDEV tests shall
41、be performed at room ambient conditions (Method A and C), except when specified in the concerned product standard with a specified altitude or equivalent reduced pressure and temperature (Method B). Apply test voltage at a maximum rate of 50 V/s to specimens having a specified PDEV of 3 kV or less a
42、nd 100 V/s for specimens having a specified PDEV above 3 kV, until the detector indicates a sustained corona discharge PDIV or reaches two times the specified corona extinction voltage PDEV. NOTE A first rise of voltage is necessary to activate the electron form (important to engage the phenomenon o
43、f partial discharges), which is situated at a level of tension superior to 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 discharge s are repetitive dur
44、ing more than one second. If sustained corona discharge PDIV is indicated, 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
45、have not been observed at two times the specified partial discharges 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. Copyright ASD-STAN Provided by IHS under license with AECMA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-
