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Introduction to IEC 61000-4-19 Differential Mode Conducted Immunity

Release time:

2023-07-19 15:29

Source:

　　1 Introduction

Electromagnetic compatibility is the ability of electrical and electronic equipment or systems to work properly in their electromagnetic environment without constituting an intolerable electromagnetic disturbance to anything in that environment. Electromagnetic compatibility is one of the important factors affecting the environment and product quality, and its standardization has attracted widespread attention at home and abroad.

With the increasing update of industrial electronics, electronic products will be exposed to more complex electromagnetic environment. This has greater requirements for the electromagnetic compatibility of electronic products, and this paper mainly discusses the low-frequency differential mode conduction immunity. In our daily life, some electronic products are often close to inverters (such as elevator drives, ski lift drives, photovoltaic (PV) facilities), smart meters with PLC data transmission functions, switching power supplies (such as compact lamps, computers and televisions), uninterruptible power supplies (UPS), variable speed drives (such as heat pumps), digital video disc players (DVD), the interference generated by such equipment is mainly 2~150kHz differential mode conduction disturbance, which may cause great harm to some electronic products (induction products, such as electric meters, dimming lights, card readers, credit card terminals, alarm systems, microwave ovens, smart keys, etc.), which will lead to abnormal functions and performance degradation.

　　2 Introduction to the test

Introduction of 2.1 Test Waveform

Differential mode conducted disturbances and communication signals in the frequency range of 2kHz to 150kHz can affect the performance of equipment and systems installed in all electromagnetic environments. Therefore, differential mode disturbances and communication signals are considered in this frequency band. Compared with the coupling to other ports, these disturbances and communication signals can be more strongly coupled to the AC power supply port. In order to verify such immunity, IEC 61000-4-19 Electromagnetic Compatibility Test and Measurement Technology AC Power Supply Port 2 kHz ~ 150 kHz Differential Mode Conducted Disturbance and Communication Signal Immunity Test specifies two kinds of voltage and current tests in the frequency range of 2 kHz ~ 150 kHz:

2.1.1 CW pulse test waveform with intermittent period

The test is carried out as follows: a sinusoidal signal (CW) pulse sequence is applied, the frequency fi is increased from 2kHz to 150kHz, and the interval is specified as follows (see figure below):

A, the duration (dwell time) of each CW pulse is Tpulse.

B, between CW pulses, the test signal (voltage or current) level is 0, and the duration Tpause is 300ms ± 200ms.

C. The dwell time Tpulse should not be shorter than the time required for the EUT to be excited and produce a response, at least not shorter than 3s.

D, the duration of one test cycle for each specific CW test frequency is Tpulse Tpause.

E, the initial frequency of CW test signal shall be 2kHz, and the frequency step shall be increased by 2%, I .e. fi +1=1.02 ×fi.

F, The test voltage (frequency fi,fi 1) does not have to be synchronized with the zero crossing of the CW test signal at the point of turn-off at the end of the CW pulse and at the point of turn-on at the beginning of the CW pulse.

CW pulse test waveform with intermittent period for differential mode test

2.1.2 Rectangular modulation PM test waveform

The modulation PM is applied, the CW frequency in the PM is increased from 2kHz to 150kHz, and there are 4 PM frequencies for modulation with a duty cycle of 50% (see the figure below).

A, when the frequency is fi, the duration (dwell time) of the pulse sequence is Tpulse = 3s for each PM modulation frequency.

B, the starting frequency of PM should be 2kHz, and the frequency step should be increased by 2%, I .e. fi +1=1.02 ×fi. The duration of the pause period between the two dwell times is 300ms ± 200ms. For the four specified tests with rectangular PM modulation, the modulation frequency f was 3Hz,101Hz,301Hz and 601Hz, respectively.

C, when the modulation frequency is fmod, the modulation period Tmod = 1/fmod.

D, The time points at the beginning and end of the pulse need not be synchronized with the zero crossing of the pulse.

Rectangular Pulse Modulation Test Waveform for Differential Mode Test

2.2 differential mode voltage test

2.2.1 Schematic diagram of differential mode voltage test connection

Note:

1. Three-phase is taken as an example in the drawing, and the wiring diagram is L1 ~ N

2. When EUT is single-phase power input, the differential mode voltage test shall be carried out according to the L-N; When EUT is three-phase power input, the differential mode voltage test shall be carried out according to the L1-N, L2-N, L3-N, L1-L2, L2-L3 and L3-L1

2.2.2 Differential mode voltage test grade

The following table and frequency diagram give the test levels for the differential mode voltage test for the AC power port in the frequency range of 2kHz to 150kHz.

　　

2.3 differential mode current test

2.3.1 Schematic diagram of differential mode current test connection

　　

Note:

1. Three-phase is taken as an example in the drawing, and the wiring diagram is L1

2. When EUT is single-phase power input, the differential mode current test shall be carried out according to L and N; When EUT is three-phase power input, the differential mode current test shall be carried out according to L1, L2, L3 and N

2.3.2 Differential mode current test level

The following tables and frequency diagrams give the test levels for differential mode current tests in the frequency range 2kHz to 150kHz.

　　

Selection of 2.4 Test Level

The environment is classified according to the following rules:

2.4.1 Class 1: Well-protected environment

The installation method has the following characteristics:

A. The internal power supply network is isolated from the distribution network, for example, a special isolation transformer is used;

B. Through grounding and special filtering, the electronic equipment sufficiently attenuates the potential differential mode disturbance signal transmitted through the facility to prevent interference from entering and leaving the network.

Such special installations may only be seen in laboratories and specially protected industrial environments. The computer room may represent such an environment.

2.4.2 Category 2: Protected environment

The installation method has the following characteristics:

A, direct connection with low-voltage power grid;

B. Through grounding and special filtering, the electronic equipment sufficiently attenuates the potential differential mode disturbance signal transmitted through the facility to prevent interference from entering and leaving the network.

Such installations may occur in commercial, residential and industrial environments where special interference protection measures are in place. No power converter is used to inject stray current into the ground grid.

Such environments may be represented by control rooms or terminal rooms within specialized buildings of plants and power stations.

2.4.3 Category 3: Typical residential, commercial and light industrial environments

The installation method has the following characteristics:

A, Direct connection with low or medium voltage grid;

B. The electronic equipment is connected to the grounding system (grounding network) of the facility;

C, a power converter that injects stray current into the ground grid is used.

2.4.4 Category 4: Harsh Industrial Environment

The installation method has the following characteristics:

A, Direct connection with low or medium voltage grid;

B. The electronic equipment is connected to the grounding system (grounding network) of the facility, which is also the common ground of high-voltage equipment and systems;

C, a power converter that injects stray current into the ground grid is used.

Gas-insulated substations, outdoor high-voltage (HV) substations, associated power plants may represent such environments.

Generally, this rating is not appropriate for residential and commercial environments.

2.4.5 Class X: Special environment to be analyzed

Through analysis or investigation of special installation conditions, higher or lower immunity requirements than the corresponding test level of the above categories can be specified.

Century Wisdom (Suzhou) Testing Technology Co., Ltd

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