BSI PD IEC/TR 62153-4-1:2010
$215.11
Metallic communication cable test methods – Electromagnetic compatibility (EMC). Introduction to electromagnetic (EMC) screening measurements
| Published By | Publication Date | Number of Pages |
| BSI | 2010 | 76 |
Screening (or shielding) is one basic way of achieving electromagnetic compatibility (EMC). However, a confusingly large number of methods and concepts is available to test for the screening quality of cables and related components, and for defining their quality. This technical report gives a brief introduction to basic concepts and terms trying to reveal the common features of apparently different test methods. It should assist in correct interpretation of test data, and in the better understanding of screening (or shielding) and related specifications and standards.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 4 | CONTENTS |
| 7 | FOREWORD |
| 9 | 1 Scope 2 Normative references |
| 10 | 3 Electromagnetic phenomena Figures Figure 1 – Total electromagnetic field (Et, Ht) |
| 11 | Figure 2 – Defining and measuring screening parameters – A triaxial set-up |
| 12 | 4 The intrinsic screening parameters of short cables 4.1 General 4.2 Surface transfer impedance, ZT 4.3 Capacitive coupling admittance, YC |
| 13 | Figure 3 – Equivalent circuit for the testing of ZT Figure 4 – Equivalent circuit for the testing of Yc = jωCT |
| 14 | 4.4 Injecting with arbitrary cross-sections 4.5 Reciprocity and symmetry 4.6 Arbitrary load conditions 5 Long cables – coupled transmission lines Figure 5 – Electrical quantities in a set-up that is matched at both ends |
| 17 | Tables Table 1 – The coupling transfer function T (coupling function)a |
| 18 | Figure 6 – The summing function S{L·f} for near and far end coupling |
| 19 | Figure 7 – Transfer impedance of a typical single braid screen Figure 8 – The effect of the summing function-coupling transfer function of a typical single braid screen cable |
| 20 | Figure 9 – Calculated coupling transfer functions Tn and Tf for a single braid – ZF = 0 Figure 10 – Calculated coupling transfer functions Tn and Tf for a single braid – Im(ZT) is positive and ZF = +0,5 x Im (ZT) at high frequencies |
| 21 | Figure 11 – Calculated coupling transfer functions Tn and Tf for a single braid – Im(ZT) is negative and ZF = –0,5 x Im(ZT) at high frequencies |
| 22 | 6 Transfer impedance of a braided wire outer conductor or screen Figure 12 – L·S: the complete length dependent factor in the coupling function T |
| 23 | Figure 13 – Transfer impedance of typical cables |
| 24 | Figure 14 – Magnetic coupling in the braid Complete flux Figure 15 – Magnetic coupling in the braid Left-hand lay contribution Figure 16 – Magnetic coupling in the braid Right-hand lay contribution |
| 25 | Figure 17 – Complex plane, ZT = Re ZT + j Im ZT , frequency f as parameter Figure 18 – Magnitude (amplitude), | ZT (f) | |
| 26 | Figure 19 – Typical ZT (time) step response of an overbraided and underbraided single braided outer conductor of a coaxial cable |
| 27 | Figure 20 – ZT equivalent circuits of a braided wire screen |
| 28 | 7 Test possibilities 7.1 General 7.2 Measuring the transfer impedance of coaxial cables 7.3 Measuring the transfer impedance of cable assemblies |
| 29 | 7.4 Measuring the transfer impedance of connectors 7.5 Calculated maximum screening level |
| 30 | Figure 21 – Comparison of signal levels in a generic test setup |
| 32 | Table 2 – Screening effectiveness of cable test methods for surface transfer impedance ZT |
| 34 | 8 Comparison of the frequency response of different triaxial test set-ups to measure the transfer impedance of cable screens 8.1 General 8.2 Physical basics Figure 22 – Triaxial set-up for the measurement of the transfer impedance ZT |
| 35 | Figure 23 – Equivalent circuit of the triaxial set-up |
| 36 | Table 3 – Load conditions of the different set-ups |
| 37 | 8.3 Simulations |
| 38 | Table 4 – Parameters of the different set-ups |
| 39 | Figure 24 – Simulation of the frequency response for g Figure 25 – Simulation of the frequency response for g |
| 40 | Figure 26 – Simulation of the frequency response for g Figure 27 – Simulation of the frequency response for g |
| 41 | Figure 28 – Simulation of the 3 dB cut off wavelength (L/λ1) |
| 42 | Figure 29 – Interpolation of the simulated 3 dB cut off wavelength (L/λ1) Table 5 – Cut-off frequency length product |
| 43 | Figure 30 – 3 dB cut-off frequency length product as a function of the dielectric permittivity of the inner circuit (cable) |
| 44 | Figure 31 – Measurement result of the normalised voltage drop of a single braid screen in the triaxial set-up |
| 45 | Figure 32 – Measurement result of the normalised voltage drop of a single braid screen in the triaxial set-up |
| 46 | Figure 33 – Triaxial set-up (measuring tube), double short circuited method Table 6 – Typical values for the factor v, for an inner tube diameter of 40 mm and a generator output impedance of 50 Ω |
| 47 | Figure 34 – Simulation of the frequency response for g Figure 35 – Simulation of the frequency response for g |
| 48 | Figure 36 – Simulation of the frequency response for g Figure 37 – Simulation of the frequency response for g |
| 49 | Figure 38 – Interpolation of the simulated 3 dB cut off wavelength (L/λ1) Table 7 – Cut-off frequency length product |
| 50 | Figure 39 – 3 dB cut-off frequency length product as a function of the dielectric permittivity of the inner circuit (cable) |
| 51 | Figure 40 – Simulation of the frequency response for g Table 8 – Material combinations and the factor n |
| 52 | Figure 41 – Interpolation of the simulated 3 dB cut off wavelength (L/λ1) Figure 42 – 3 dB cut-off frequency length product as a function of the dielectric permittivity of the inner circuit (cable) Table 9 – Cut-off frequency length product |
| 53 | 8.4 Conclusion Table 10 – Cut-off frequency length product for some typical cables in the different set-ups |
| 54 | 9 Background of the shielded screening attenuation test method (IEC 62153 4 4) 9.1 General 9.2 Objectives Figure 43 – Definition of transfer impedance Figure 44 – Definition of coupling admittance |
| 55 | 9.3 Theory of the triaxial measuring method Figure 45 – Triaxial measuring set-up for screening attenuation |
| 56 | Figure 46 – Equivalent circuit of the triaxial measuring set-up |
| 57 | Figure 47 – Calculated voltage ratio for a typical braided cable screen |
| 58 | Figure 48 – Calculated periodic functions for εr1 = 2,3 and εr2 = 1,1 |
| 59 | Figure 49 – Calculated voltage ratio-typical braided cable screen |
| 60 | 9.4 Screening attenuation Figure 50 – Equivalent circuit for an electrical short part of the length Δl and negligible capacitive coupling |
| 61 | 9.5 Normalised screening attenuation |
| 62 | 9.6 Measured results Table 11 – Δa in dB for typical cable dielectrics |
| 63 | Figure 51 – as of single braid screen, cable type RG 58, L = 2 m Figure 52 – as of single braid screen, cable type RG 58, L = 0,5 m |
| 64 | 9.7 Comparison with absorbing clamp method Figure 53 – as of cable type HF 75 0,7/4,8 02YCY Figure 54 – as of cable type HF 75 1,0/4,8 02YCY Figure 55 – as of double braid screen, cable type RG 223 |
| 65 | 9.8 Practical design of the test set-up Table 12 – Comparison of results of some coaxial cables |
| 66 | 9.9 Influence of mismatches Figure 56 – Schematic for the measurement of the screening attenuation as Figure 57 – Short circuit between tube and cable screen of the CUT |
| 67 | Figure 58 – Triaxial set-up, impedance mismatches |
| 68 | Figure 59 – Calculated voltage ratio including multiple reflections caused by the screening case Figure 60 – Calculated voltage ratio including multiple reflections caused by the screening case |
| 69 | Annex A (normative) List of symbols |
| 72 | Bibliography |
