HD-21.2-S2-A13-1995.pdf
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1、- CENELEC HD*21.2*S2/ A13 95 I 3404583 0159438 902 m HARMONIZATION DOCUMENT HD 21.2 S2lA13 DOCUMENT DHARMONISATION HARMONISIERUNGSDOKUMENT June 1995 UDC (621.31 5.21 1.2+ 621.31 5.321.027.475-036.743.22-001.2.001.4 ICs 29.060.20 Descriptors: See HD 21.2 S2 English version Polyvinyl chloride insulate
2、d cables of rated voltages up to and including 450/750 V Part 2: Test methods Conducteurs et cbles isoles au polychlorure de vinyle, de tension assigne au plus gale 450/750 V Partie 2: Mthodes dessais Polyvinylchlorid-isolierte Leitungen mit Nennspannungen bis 450/750 V Teil 2: Prfverfahren This ame
3、ndment Al3 modifies the Harmonization Document HD 21.2 S2:1990; it was approved by CENELEC on 1995-05-1 5. CENELEC members are bound to comply with the CENICENELEC Internal Regulations which stipulate the conditions for implementation of this amendment on a national level. Up-to-date lists and bibli
4、ographical references concerning such national implementation may be obtained on application to the Central Secretariat or to any CENELEC member. This amendment exists in three official versions (English, French, German). CENELEC members are the national electrotechnical committees of Austria, Belgi
5、um, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Eiectrotechnique Europisches Komitee fr Ele
6、ktrotechnische NOtTnUnQ Centrai Secretariat: rue de Stassart 35, B *- 1050 Brussels 1995 Copyright reserved to CENELEC members Ref. No. HD 21.2 S2:1990/A13:1995 E - - - 7 CENELEC HD*ZL=E!*SZ/ AL3 95 m 3404583 0359439 849 Page 2 HD 21.2 S2:1990/A13:1995 Foreword This amendment was prepared by the Tec
7、hnical 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 Al 3 to HD 21.2 S2:1990 on 1995-05-1 5. The following dates were fixed: - latest date by which the existence of the amendment has to be ann
8、ounced at national level (doa) 1996-01 -01 - latest date by which the amendment has to be implemented at national level by publication of a harmonized national standard or by endorsement . (dop) 1996-07-01 - latest date by which the national standards conflicting with the amendment have to be withdr
9、awn (daw) 1996-07-01 For products which have complied with HD 21.2 S2: 1990 and its amendments A2: 1 990, A3:1993, A4:1993, A6:1995 and A l 1 :1995 before 1996-07-01, as shown by the manufacturer or by a certification body, this previous standard may continue to apply for production until 1997-07-01
10、 . -,-,- Page 3 HD 21.2 S2:1990/A13:1995 Because of screened cables, replace the existing sub-clause 2.2 by the following: 2.2 Voltage test carried out on comaleted cables A sample of cable as delivered shall be immersed in water if the cable has no metallic layer. The length of the sample, the temp
11、erature of the water and the duration of immersion are given in Part 1, Table III. A voltage shall be applied in turn between each conductor and all the others connected together and to the metallic layer, if any or to the water; and between all conductors connected together and the metallic layer o
12、r water. The voltage and the duration of its application are given for each case in Part 1, Table 111. Add a new sub-clause 2.7 to HO 21.2: 2.7 Screenina efficiency 2.7.1 General The screening efficiency of a cable depends both on the screening against currents and the screening against voltages. Th
13、e screening efficiency against currents is specified in terms of the transfer impedance due to resistive and magnetic coupling per unit length, against voltages in terms of the transfer admittance due to electric coupling (see Note below) per unit length. Transfer impedance is defined in an elementa
14、ry length of cable as the ratio of the voltage measured along the screen in the disturbed system to the current flowing in the interfering system. This may be of interest at any frequency up to 10,000 MHz. In general, there is no problem where homogeneous cylindrical shields are used since the scree
15、ning effect in such cases can be readily calculated, but where a braided or taped construction is employed it becomes necessary to measure the screening efficiency. The present state of experience shows that the surface transfer impedance remains constant at frequencies from O Hz to 0.1 MHz or 1 MHz
16、, depending on the type of cable and is equal to the direct current resistance of the screen. At frequencies over 0.1 MHz or 1 MHz the transfer impedance increases. Depending on the construction of the screen, this increase starts directly or after having passed through a minimum. Over 1 O MHz to 15
17、 MHz, the increase is proportional to the frequency. Transfer admittance is defined in an elementary length of cable as the ratio,of the current flowing into the disturbed system to the voltage originating it in the specified interfering system. Measurements show that the transfer admittance may be
18、represented by a capacitance which is independent of frequency from audio frequencies up to 1,000 MHz at least. Note: Attention is drawn to the fact that in some countries the term transfer admittance is taken to be the reciprocal of transfer impedance which is not the case in this standard. - ,7 CE
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- HD 21.2 S2 A13 1995
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