Content of CE-EMC testing

release time :2023-07-13 15:12:01    

What are the EMC electromagnetic compatibility testing items?

The electromagnetic compatibility testing projects mainly include:

1. Radiation emission test

Test the radiation emissions of electronic, electrical, and electromechanical equipment and their components, including those from all components,
cables, and wiring, to determine whether their radiation meets the requirements of the standard and consistently affects other equipment in the same
environment during normal use.

2. Conducted disturbance test

To measure the disturbance transmitted by devices from power and signal ports to the power grid or signal network.

3. Electrostatic discharge immunity test

Test the anti electrostatic discharge interference ability of a single device or system, which simulates the discharge of operators or objects when they
come into contact with the equipment; The discharge of a person or object towards adjacent objects. Electrostatic discharge may have the following
consequences: direct damage to semiconductor devices through energy exchange, changes in electric and magnetic fields caused by discharge, and
equipment malfunction. The noise current caused by discharge leads to device malfunction.

4. Immunity testing of radio frequency radiated electromagnetic fields

The interference to equipment is often caused by equipment operation, maintenance and safety inspection personnel when using mobile devices.
Radio frequency radiation interference will be generated by radio stations, television Launch pad, mobile radio transmitters and various industrial
electromagnetic radiation sources, as well as parasitic radiation generated by electric welding machines, thyristor rectifiers and fluorescent lamps
when they are working. The purpose of the test is to establish a common standard to evaluate the resistance of electronic equipment to radio
frequency radiated electromagnetic field interference.

5. Immunity testing of fast transient pulse groups

The switching of inductive loads by mechanical switches in a circuit usually causes interference with other electrical and electronic devices in the same
circuit. The mechanism of testing is to utilize the accumulation effect of distributed capacitance energy on the line when the common mode current
generated by group pulses flows through the line. When the energy accumulates to a certain extent, it may cause errors in the operation of the line
(or even equipment). Usually, once the testing equipment makes an error, it will continuously make mistakes. Even if the pulse voltage is slightly reduced,
the phenomenon of continuous error situations can be explained. Pulses appear in groups, with high pulse repetition frequency, short waveform rise time,
and low energy. Generally, it does not cause equipment failure, and it is common for equipment to malfunction.

6. Surge immunity test

Lightning strikes mainly simulate indirect lightning, such as lightning strikes on outdoor lines, where a large amount of current flows through external lines
or grounding resistors, resulting in interference voltage. Voltage and current induced on the line, electromagnetic field generated when lightning strikes
nearby objects, voltage and current induced on the line, interference introduced when lightning strikes the ground and ground current passes through
the public Earthing system.

Switching transient: The interference generated during the switching of the main power system, and the interference generated during the jumping of
large switches in the same power grid.

7. Conducted Immunity Test for RF Field Induction

Normally, the length of the lead wire of the device may be equivalent to several wavelengths of the interference frequency, and these leads can cause
interference to the device through conduction. Devices without conductive cables do not need to undergo this test. In general, the size of the interfered
device is much smaller than the wavelength of the interference wave with lower frequencies. In contrast, the length of the device lead may reach several
wavelengths of the interference wave. In this way, the device lead becomes a passive antenna, receiving induction from the RF field, and becomes a
conductive interference that invades the device's interior. Ultimately, the near-field electromagnetic field formed by the RF voltage and current affects
the device's operation.

8. Voltage drop, interruption during interruption, and voltage gradient immunity test

Transient voltage drops and interruptions are caused by faults in the power grid, substation facilities, or sudden changes in load. Voltage changes are
caused by continuous changes in the load connected to the power grid.

Typical test site: 10 meter anechoic chamber

Adopting Boresight dual antenna testing technology, the testing frequency is 9KHz-40GHz, and the three-phase or single-phase testing current can reach
up to 600A AC (DC) current at a large capacity. The turntable can bear a load of 3.5 tons at a large capacity; The shielding effectiveness, normalized site
attenuation, field uniformity, site voltage standing wave ratio, and background noise can all meet the requirements of the standard well.

Various electronic products or devices generate unnecessary high-frequency radio waves during use. These radio waves are often scattered through power
lines or by radiating electromagnetic waves, thus infiltrating or being received by other electronic product devices around them, affecting their normal
functioning. That is, electromagnetic pollution, and the problem of this kind of pollution is not unique today. It is only because with the progress of technology,
the increasing number of electronic products, the increasing number of electronic devices, and the increasing intensity of use, the importance of electromagnetic
compatibility has received widespread attention.

Electromagnetic compatibility (EMC):

The ability of a device or system to operate normally in its electromagnetic environment without causing unbearable electromagnetic interference to anything
in that environment.

Electromagnetic interference (EMI) refers to the degradation of equipment, transmission channels, or system performance caused by electromagnetic interference.

Electromagnetic susceptibility (EMS) refers to the ability of a device, device, or system to avoid performance degradation in the presence of electromagnetic interference.

Note: High sensitivity and low immunity. EMC=EMI+EMS

EMC:

Power Line Conducted Emission Test

Radiated Emission Test

Power Disturbance Test

Harmonic Current Emission Test

Voltage Fluctuations&Flicker Test

Electrostatic Discharge Test

RF Field Strength Susceptibility Test

Electrical Fast Transient/Burst Test

Surge Test

Conducted Currents Susceptibility Test

Magnetic Field Immunity Test

Voltage Dips And Interruptions Test

The EMC electromagnetic compatibility testing mainly includes two aspects:

1、 Electromagnetic sensitivity testing, measurement of immunity to electrical and electronic equipment;

2、 Measurement of electromagnetic interference, measurement of radio disturbance characteristics of equipment.

The purpose of electromagnetic compatibility measurement is to provide reference and basis for improving the electromagnetic compatibility ability of electrical
and electronic equipment in practical work. In order to make the testing more meaningful and the measurement results comparable, the standardization of
electromagnetic compatibility testing becomes extremely important.