Electromagnetic Compatibility — Testing and Measurement Techniques — Immunity to Conducted Disturbances, Induced by Radio-frequency Fields
1 Scope
This part of GB/T 17626 relates to the conducted immunity requirements of electrical and electronic equipment to electromagnetic disturbances coming from intended radio-frequency transmitters in the frequency range 150 kHz up to 80 MHz. Equipment not having at least one conducting wire and/or cable (such as mains supply, signal line or earth connection) which can couple the equipment to the disturbing RF fields is excluded from the scope of this publication.
Note 1: Test methods are defined in this part of GB/T 17626 to assess the effect that conducted disturbing signals, induced by electromagnetic radiation, have on the equipment concerned. The simulation and measurement of these conducted disturbances are not adequately exact for the quantitative determination of effects. The test methods defined are structured for the primary objective of establishing adequate repeatability of results at various facilities for quantitative analysis of effects.
The object of this standard is to establish a common reference for evaluating the functional immunity of electrical and electronic equipment when subjected to conducted disturbances induced by RF fields. The test method documented in this part of IEC 61000 describes a consistent method to assess the immunity of an equipment or system against a defined phenomenon.
Note 2: As described in GB/Z 18509[1], this standard is a basic EMC publication for use by relevant product committees. As also stated in GB/Z 18509[1], the product committees are responsible for determining whether this immunity test standard should be applied or not, and if applied, they are responsible for determining the appropriate test levels and performance criteria. The National Technical Committee on Electromagnetic Compatibility of Standardization Administration of China (SAC/TC 246) and its sub-committees cooperate with relevant product committees for standardization to evaluate test levels and performance criteria for specific immunity tests on their products.
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.
IEC 60050(161) International Electrotechnical Vocabulary (IEV) — Chapter 161: Electromagnetic Compatibility
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 as well as the following apply.
3.1
artificial hand
electrical network simulating the impedance of the human body under average operational conditions between a hand-held electrical appliance and earth
Note: The construction should be in accordance with CISPR 16-1-2[3].
[IEC 60050-161:1990, 161-04-27]
3.2
auxiliary equipment; AE
equipment necessary to provide the equipment under test (EUT) with the signals required for normal operation and equipment to verify the performance of the EUT
3.3
clamp injection
clamp injection is obtained by means of a clamp-on “current” injecting device on the cable
3.4
clamp injection device
clamp-on “current” injecting device on a cable being either a current clamp or an electromagnetic clamp
3.4.1
current clamp
transformer, the secondary winding of which consists of the cable into which the injection is made
3.4.2
electromagnetic clamp (EM clamp)
injection device with combined capacitive and inductive coupling
3.5
common mode impedance
ratio of the common mode voltage and the common mode current at a certain port
Note: This common mode impedance can be determined by applying a unity common mode voltage between the terminal(s) or screen of that port and a reference plane (point). The resulting common mode current is then measured as the vectorial sum of all currents flowing through these terminal(s) or screen, see also Figures 8a) and 8b).
3.6
coupling factor
ratio given by the open-circuit voltage (e.m.f.) obtained at the EUT port of the coupling (and decoupling) device divided by the open-circuit voltage obtained at the output of the test generator
3.7
coupling network
electrical circuit for transferring energy from one circuit to another with a defined impedance
Note: Coupling and decoupling devices can be integrated into one box [coupling and decoupling network (CDN)] or they can be in separate networks.
3.8
coupling/decoupling network; CDN
electrical circuit incorporating the functions of both the coupling and decoupling networks
3.9
decoupling network (decoupling device)
electrical circuit for preventing test signals applied to the EUT from affecting other devices, equipment or systems that are not under test
3.10
test generator
generator (RF generator, modulation source, attenuators, broadband power amplifier and filters) capable of generating the required test signal
Note: See Figure 3.
3.11
electromotive force (e.m.f.)
voltage at the terminals of the ideal voltage source in the representation of an active element
3.12
measurement result
Umr
voltage reading of the measurement equipment
3.13
voltage standing wave ratio; VSWR
ratio of a maximum to an adjacent minimum voltage magnitude along the line
4 General
The source of disturbance covered by this part is basically an electromagnetic field, coming from intended RF transmitters, that may act on the whole length of cables connected to installed equipment. The dimensions of the disturbed equipment, mostly a sub-part of a larger system, are assumed to be small compared with the wavelengths of the interfering signals. The leads entering and exiting the EUT (e.g. mains, communication lines, interface cables) behave as passive receiving antenna networks and signal conduction paths for both intentional and unintentional signals.
Between those cable networks, the susceptible equipment is exposed to currents flowing “through" the equipment. Cable systems connected to an equipment are assumed to be in resonant mode (λ/4, λ/2 open or folded dipoles) and as such are represented by coupling and decoupling devices having a common mode impedance of 150 Ω with respect to a reference ground plane. Where possible the EUT is tested by connecting it between two 150 Ω common mode impedance connections: one providing an RF source and the other providing a return path for the current.
This test method subjects the EUT to a source of disturbance comprising electric and magnetic fields, simulating those coming from intentional RF transmitters. These disturbing fields (E and H) are approximated by the electric and magnetic near-fields resulting from the voltages and currents caused by the test setup as shown in Figure 1 a).
The use of coupling and decoupling devices to apply the disturbing signal to one cable at a time, while keeping all other cables nonexcited [see Figure 1 b)], can only approximate the real situation where disturbing sources act on all cables simultaneously, with a range of different amplitudes and phases.
Coupling and decoupling devices are defined by their characteristics given in 6.2.1. Any coupling and decoupling device fulfilling these characteristics can be used. The CDNs in Annex D are only examples of commercially available networks.
试验信号发生器 Test generator
Zce Common mode impedance of the CDN system, Zce = 150 Ω
Note: The 100 Ω resistors are included in the CDNs. The left input is loaded by a (passive) 50 Ω load and the right input is loaded by the source impedance of the test generator.
U0 Test generator source voltage (e.m.f.)
Ucom Common mode voltage between EUT and reference plane
Icom Common mode current through the EUT
Jcom Current density on conducting surface or current on other conductors of the EUT
E, H Electric and magnetic fields
a) Diagram showing EM fields near the EUT due to common mode currents on its cables
Figure 1 Immunity Test to RF Conducted Disturbances
参考地平面 Reference ground plane
射频信号源 RF generator
试验信号发生器 Test generator
支撑 support
Schematic setup for immunity test used for CDN
参考地平面 Reference ground plane
如果可能 where possible
射频信号源 RF generator
试验信号发生器 Test generator
注入钳 Injection clamp
支撑 support
T Termination 50 Ω
T2 Power attenuator (6 dB)
CDN Coupling and decoupling network
Injection clamp Current clamp or EM clamp
Schematic setup for immunity test used for injection clamp
b) Schematic setup for immunity test to RF conducted disturbances
Figure 1 (continued)
5 Test Levels
According to this standard, tests are required for induced disturbances caused by electromagnetic fields coming from RF transmitters in the frequency range 150 kHz to 80 MHz.
The open circuit test levels (e.m.f.) of the unmodulated disturbing signal, expressed in r.m.s., are given in Table 1.
Table 1 Test Levels
Frequency range 150 kHz to 80 MHz
Level Voltage level (e.m.f.)
U0/V U0/dB(µV)
1 1 120
2 3 129.5
3 10 140
X Special
Note: "X" can be any level, above, below or in between the others. The level has to be specified in the dedicated equipment specification.
The test levels are set at the EUT port of the coupling devices, see 6.4. For testing of the equipment, this signal is 80% amplitude modulated with a 1 kHz sine wave to simulate actual threats. The effective amplitude modulation is shown in Figure 2. Guidance for selecting test levels is given in Annex C.
Note 1: IEC 61000-4-3[2] also defines test methods for establishing the immunity of electrical and electronic equipment against radiated electromagnetic energy. It covers frequencies above 80 MHz. Product committees can decide to choose a lower or higher transition frequency than 80 MHz (see Annex B).
Note 2: Product committees can select alternative modulation schemes.
a）未调制射频信号 a) Unmodulated RF signal
b）80%AM射频调制信号 b) Modulated RF – signal 80% AM
Figure 2 Open Circuit Waveforms at the EUT Port of a Coupling Device for Test Level 1
6 Test Equipment and Level Adjustment Procedures
6.1 Test Generator
The test generator includes all equipment and components for supplying the input port of each coupling device with the disturbing signal at the required signal level at the appropriate injection point. A typical arrangement comprises the following items which may be separate or integrated into one or more test instruments (see 3.10 and Figure 3):
— RF generator(s), G1, capable of covering the frequency band of interest and of being amplitude modulated by a 1 kHz sine wave with a modulation depth of 80%. They shall have manual control (e.g. frequency, amplitude, modulation index) or in the case of RF synthesizers, they shall be programmable with frequency-dependent step sizes and dwell times;
— attenuator T1, (typically 0 dB ... 40 dB) of adequate frequency rating to control the disturbing test source output level. T1 may be included in the RF generator and is optional;
— RF switch S1, by which the disturbing test signal can be switched on and off when measuring the immunity of the EUT. S1 may be included in the RF generator and is optional;
— broadband power amplifier(s), PA, may be necessary to amplify the signal if the output power of the RF generator is insufficient;
— low-pass filters (LPF) and/or high-pass filters (HPF) may be necessary to avoid interference caused by (higher order or sub-) harmonics with some types of EUT, for example RF receivers. When required they shall be inserted in between the broadband power amplifier, PA, and the attenuator T2;
— attenuator T2, (fixed ≥ 6 dB), with sufficient power ratings. T2 is provided to reduce VSWR to the power amplifier caused by the mismatch of the coupling device.
Note: T2 can be included in a CDN and can be left out if the output impedance of the broadband power amplifier remains within the specification under any load condition.
Characteristics of the test generator are given in Table 2.
Table 2 Characteristics of the Test Generator
Output impedance 50 Ω, VSWR<1.5
Harmonics and distortion within 150 kHz and 80 MHz, any spurious signal shall be at least 15 dB below the carrier level, measured at the EUT port of the coupling device. The -15 dBc can also be measured directly at the output of the amplifier.
Amplitude modulation internal or external
with
1 kHz ± 0.1 kHz sine wave
Output level sufficiently high to cover test level (see also Annex E, Table E.1)
Note 1: for current clamps, the -15 dBc can be measured at either side of the test jig.
Note 2: The harmonics and distortion are measured in continuous wave (CW) at 1,8 times the test level without modulation.
射频信号源 RF generator
宽带功率放大器 Broadband power amplifier
非必需 optional
G1: RF generator
PA: Broadband power amplifier
LPF/HPF Low pass filter and/or high pass filter (optional)
T1: Variable attenuator
T2: Fixed attenuator (6 dB)
S1 RF switch
Figure 3 Test Generator Setup
6.2 Coupling and Decoupling Devices
6.2.1 General
Coupling and decoupling devices shall be used for appropriate coupling of the disturbing signal (over the entire frequency range, with a defined common mode impedance at the EUT port) to the various cables connected to the EUT and for preventing applied test signals from affecting other devices, equipment and systems that are not under test.
The coupling and decoupling devices can be combined into one box (a CDN or an EM clamp) or can consist of several parts.
The preferred coupling and decoupling devices are the CDNs, for reasons of test reproducibility and protection of the AE. The main coupling and decoupling device parameter, the common mode impedance seen at the EUT port, Zce, is specified in Table 3. If CDNs are not applicable or available on the market, other injection methods can be used. Rules for selecting the appropriate injection method are given in 7.4.1. Other injection methods, due to their electrical properties, are unlikely to meet the parameters of Table 3.
Table 3 Main Parameter of the Combination of the Coupling and Decoupling Device
Parameter Frequency band
0.15 MHz to 24 MHz 24 MHz to 80 MHz
|Zce| 150 Ω ± 20 Ω 150 Ω-45Ω+60Ω
Note 1: A CDN may not be applicable if the internal signal attenuation has an unacceptable influence on the intended signal.
Note 2: Neither the argument of Zce nor the decoupling factor between the EUT port and the AE port are specified separately. These factors are embodied in the requirement that the tolerance of |Zce| shall be met with the AE port open or short-circuited to the reference ground plane.
Note 3: Details for clamps are given in Annex A.
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 General
5 Test Levels
6 Test Equipment and Level Adjustment Procedures
6.1 Test Generator
6.2 Coupling and Decoupling Devices
6.3 Verification of the Common Mode Impedance at the EUT Port of Coupling and Decoupling Devices
6.4 Setting of the test generator
7 Test Setup and Injection Methods
7.1 Test Setup
7.2 EUT Comprising a Single Unit
7.3 EUT Comprising Several Units
7.4 Rules for Selecting Injection Methods and Test Points
7.5 CDN Injection Application
7.6 Clamp Injection Application When the Common Mode Impedance Requirements Can Be Met
7.7 Clamp Injection Application When the Common Mode Impedance Requirements Cannot be Met
7.8 Direct Injection Application
8 Test Procedure
9 Evaluation of the Test Results
10 Test Report
Annex A (Normative) EM and Decoupling Clamps
Annex B (Informative) Selection Criteria for the Frequency Range of Application
Annex C (Informative) Guide for Selecting Test Levels
Annex D (Informative) Information on Coupling and Decoupling Networks
Annex E (Informative) Information for the Test Generator Specification
Annex F (Informative) Test Setup for Large EUTs
Annex G (Informative) Measurement Uncertainty of the Voltage Test Level
Annex H (Informative) Measurement of AE Impedance
Annex I (Informative) Port to Port Injection
Annex J (Informative) Amplifier Compression and Non-linearity
Bibliography
