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Eight main EMC test items.

February 22, 2021


1. Radiation emission test

Test the radiated emission of electronic, electrical and electromechanical equipment and its components, including the radiated emission from all components, cables and connections, to identify whether the radiation meets the requirements of the standard, and it will affect the radiation in the same environment during normal use. other devices.

2. Conducted disturbance test

In order to measure the harassment transmitted from the power port and signal port to the power grid or signal network.

3. Electrostatic discharge immunity test

Test the anti-static discharge interference ability of a single device or system, which simulates: the discharge of the operator or object when touching the device; the discharge of the person or object to the nearby objects. Electrostatic discharge may have the following consequences: damage to semiconductor devices directly through energy exchange, changes in electric field and magnetic field caused by discharge, and malfunction of equipment. The discharged noise current causes the device to malfunction.

4. Immunity test of radio frequency radiation electromagnetic field

Interference to equipment is often caused by equipment operation, maintenance and safety inspection personnel when using mobile phones, radio stations, television transmitters, mobile radio transmitters and various industrial electromagnetic radiation sources, as well as electric welding machines, thyristor rectifiers, and fluorescent lamps Parasitic radiation generated during work will cause radio frequency radiation interference. The purpose of the test is to establish a common standard to evaluate the ability of electronic equipment to resist radio frequency radiation electromagnetic field interference.


5. Immunity test of fast transient pulse group

The switching of inductive loads by mechanical switches in a circuit usually interferes with other electrical and electronic devices in the same circuit. The mechanism of the test is to use the common mode current generated by the group pulse to flow through the line, which will accumulate the distributed capacitance energy of the line. When the energy accumulates to a certain extent, it may cause the line (or even the equipment) to work incorrectly. Normally, once the test equipment makes an error, it will continue to make mistakes. Even if the pulse voltage is slightly reduced, the error situation will still be explained. The pulses appear in groups, the pulse repetition frequency is high, the waveform rise time is short, and the energy is small. Generally, it will not cause equipment failure and cause equipment to malfunction.

6. Surge immunity test

Lightning strikes mainly simulate indirect lightning. For example, lightning strikes an outdoor line, and a large amount of current flows into the outdoor line or grounding resistance, which generates interference voltage. The voltage and current induced in the line, lightning strikes nearby objects to produce electromagnetic fields, the voltage and current induced on the line, the lightning strikes the ground, and the interference introduced when the ground current passes through the public grounding system.

Switching transients: Interference generated when the main power system is switched, or when a large switch on the same power grid is bounced.

7. Conducted immunity test for RF field induction

Under normal circumstances, the length of the leads of the equipment may be equivalent to several wavelengths of the interference frequency. These leads can cause interference to the equipment through conduction. Equipment without conductive cables does not need to do this test. Under normal circumstances, the size of the interfered device is much smaller than the wavelength of the lower frequency interference wave. 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. , Accept the induction of the radio frequency field, it becomes the conduction interference to invade the inside of the equipment, and finally the near-field electromagnetic field formed by the radio frequency voltage and current affects the operation of the equipment.

8. Voltage drop, interruption and voltage gradient immunity test

The instantaneous voltage drop and interruption are caused by the failure of the power grid and substation facilities or the sudden large changes in the load. Voltage changes are caused by continuous changes in the load connected to the grid.