EMC Test -EMS

In Chapter 5, I would like to explain the EMS (EMS) exam.The purpose is to evaluate the resistance in the electromagnetic environment assumed by the product.The exams give electromagnetic obstructions at the specified procedure, level, and confirm the operation of the test equipment.Main test items include static electricity tests, radiomagnetic field images, electrical first transgenas/burst images, surge images tests, conductivity images test, power frequency electromagnetic field test, voltage dip, temporary blocking system test.There is.

Unlike an emission (electromagnetic wave noise generated from equipment), which has long been legal regulation in many countries, based on the idea that the system (resistance to electromagnetic waves) is a product quality problem.Some countries, such as the United States, are not regulated by law.On the other hand, in Europe, with the enforcement of the EMC command, the same as the emissions in the ...Therefore, please keep in mind that it is necessary to make sure that the initiative test is required depending on the location.Let's introduce the outline of each exam.

Electrostatic imaging test

If a charged human body comes into contact with a conductive object such as an electricity or electronic device, or if it approaches sufficiently, a violent discharge may occur. This phenomenon is called ESD (Electro-Static Discharge), which can cause problems such as malfunctions and damage to electrical and electronic devices. The test simulates the dust discharge generated directly or near the EUT from such a human body or other charged objects (EUT) to evaluate the performance of the EUT when static electricity. 。 All parts that may approach the hands of the device when using the device are evaluated. It may be surprising, but the static electricity caused by the human body has a great effect on electronic devices. Although it is not so large for energy, it is often found that it is more than 10 kv for static discharge that makes people feel painful. In the electrostatic imaging test, the test level is determined to be 4 kv for contact discharge and 8 kv for air power, and the EUT function loss during the test is observed, but no deterioration in data loss is observed.

Radiation Electromagnetic Service Test Examination

In the radiant electromagnetic field implementation test, the test equipment is resistant to the electromagnetic waves of the frequency radiated from broadcasting stations and various radio devices.The test is carried out in a radio room, irradiating the electromagnetic wave of the frequency specified by the standard to the EUT, and confirms that the operation at that time is normal.The frequency range was 80MHz to 1000MHz, except for special items such as automobiles and medical devices, but as the spread of mobile phones and various wireless devices, tests over 1000MHz were required.It is necessary to irradiate all aspects for the object, that is, front, back, left and right, in some cases, to the top and bottom.During the test, it is common to install a camera for operation confirmation without entering the radio room, and check the operation of the test equipment.

Electrical First Transcription/Burst Immediate Examination

In this test, the performance of the test target device is evaluated when the "repetitive high -speed transient voltage (burst)" is performed on a power supply, signal and control port.Simply put, you can think of it as a noise that occurs when you turn on or turn off the equipment, or when the device starts or finishes.The test is intermittently applied to the EUT with a very short noise (but at a certain interval), and the Eut is tested for malfunctions when such noise is received.The test target is a power supply or cable, and a 500V to 2 kv test noise is applied.

Sage Immediate Examination

The Surge Immediate Examination is an instant for generating an unusually high voltage and confirming the operation of the target device.In the most familiar example, there are lightning strikes.It is not difficult to imagine that a large voltage / current will occur in the natural world when a lightning strike occurs, but even if it is not hit directly by lightning, a large noise on power lines and outdoor wiring also invades the general device that is connected to it.I'll come.For this reason, the Sage Immediate Examination is required for general equipment.The exams simulate the opening and closing of the transmission system from the lightning facility and the instantaneous voltage that is different from the above -mentioned burst exams to confirm the resistance of the product.It is recommended to take the last test because the product is likely to be broken.

Conductor imaging test

Conductive imaging examinations are tests that imitate the impact of power sources and input / output cables and current effects.The purpose of the test is to evaluate the case where the interference of the radio signal binds to the cable etc. and enter the test equipment as a conduction noise, so it corresponds to the wireless signal..Apply noise in the frequency range of 15 to 80MHz.Normally, the sabotage signal is applied to the power supply line using a binding/decreased network (CDN) (*2), and an EM clamp on the signal line.The standards of the operation judgment are relatively strict, and in order to maintain the reproducibility of the test, it is necessary to pay close attention according to the setup, and the difficulty is high in the exam.

Power frequency magnetic field imaging test

This is a test that simulates a 50-60 Hz magnetic field from the power supply line and checks the operation when a test target device is put in the magnetic field.This test is applied only when the test equipment is used by detecting a magnetic field such as a hole element, a dynamic microphone, or a sensor that senses a magnetic field.

Voltage dip, temporary blocking ...

It is a test that simulates the temporary decrease in the power supply voltage and the impact of the power outage.The test is performed by reducing the power supply to the device to be tested at a predetermined time and a predetermined percentage.For a short voltage decrease (voltage dip), the device is normal after the power supply voltage has returned to a normal range for long -term voltage decreases.It is required to resume.It is not necessary to break the device in these tests, but it is necessary to be careful because it may be destroyed by a device that generates a reverse electromotive force at the time of a voltage decrease or instantaneous stop, or a printer device.

This is the main initiative test.

The serialization of "EMC understandable from zero" will be the last episode next time.I would like to talk about the recent trends of EMC.