What Are EMC Countermeasure Components?
EMC countermeasure components are electronic components used for noise suppression in electrical equipment that handle signals.
Compatibility refers to the unwanted electrical noise (emissions) emitted by an electronic device without causing significant electromagnetic disturbance to other objects in the environment, and its ability to function in a given electromagnetic environment with low susceptibility to interference (immunity or susceptibility).
Emission is called EMI (electro-magnetic interference) and immunity is called EMS (electro-magnetic susceptibility), and a variety of electronic components have been developed to address these issues.
Applications of EMC Countermeasure Components
We are surrounded by many electronic devices, each of which handles electromagnetic signals and waves. If EMC countermeasures are not taken properly, some of them may malfunction, switch on without permission, or cause communication problems.
EMC countermeasure components are especially used in communication devices such as computers, mobile devices, smartphones, many home appliances, inverters, and other devices that perform actions involving signal conversion.
EMC has its own standards depending on the equipment used, for example, emissions from electric lighting, emissions from multimedia equipment, immunity of multimedia equipment, medical electrical equipment, ships, automobiles, etc.
Principle of EMC Countermeasure Components
EMC countermeasure components can be roughly divided into three categories.
Frequency Separation
If the expected noise components are on the high-frequency side, LPF (low pass filter) is effective to cut them. It functions as a filter by incorporating coils, beads, and resistors in series with the signal input and capacitors in parallel. An AC power line filter that combines a capacitor and a common mode filter is also used.
Mode Separation
When either the common mode, in which the signal is sent in the same direction to the paired lines, or the differential (normal) mode, in which the signal is sent in a different direction, is a noise component, it is effective to separate these two modes. In most cases, the common mode is an unwanted component, so components are used to attenuate it. For example, a CMF (common mode filter), ferrite core, or transmission transformer is placed in parallel with the signal.
Amplitude Separation
Noise can appear as a sudden phenomenon. Varistors and Zener diodes are incorporated in parallel to prevent transient changes in voltage, especially due to electrostatic effects as noise. These are elements whose resistance value changes depending on the voltage.
Other Information on EMC Countermeasure Components
EMC Design
EMC design, or design to satisfy EMC, has two main purposes: first, to reduce the noise output of EMI, the noise output level (commonly called emissions) emitted by electronic equipment with respect to electromagnetic noise, or EMC, which is called the electromagnetic compatibility of electronic equipment.
The second is a noise tolerance design for EMS (commonly called immunity), which is the level of noise that an electronic device can withstand without malfunction or abnormal conditions even if it accepts noise. EMC design is to ensure that both of these aspects of the electronic equipment are sufficiently satisfied with the various standards, laws, and regulations for the electrical products in which the equipment is installed.
The actual EMC design includes: EMI filters, consisting of X capacitors and line filters to reduce normal line noise between power lines; ground capacitors (commonly known as Y capacitors) to reduce common noise between ground and ground. In addition, ferrite cores, ferrite beads, common mode choke coils, electromagnetic wave absorbing sheets, and varistors and surge absorbers that clamp and remove external noise voltages, such as lightning are used in many electronic devices.
Lightning Surge Countermeasure Components
Lightning surge countermeasure components are used to prevent electronic equipment from malfunctioning or breaking due to lightning. Normally, the electromagnetic compatibility, or EMC, of electronic equipment, or the amount of electromagnetic noise emitted and the immunity to electromagnetic noise, is determined by the EMC standards for each device in which the electronic equipment is installed.
Among the above-mentioned electromagnetic noise emission and immunity standards, lightning surge countermeasure components are mounted to increase immunity to EMS standards, commonly known as immunity to noise, and especially to lightning surge tests.
The usage of surge absorbers, such as varistors and surge arresters, is to be connected to the ground in combination with a grounding capacitor, etc., in an electric circuit to release high-energy noise, including lightning coming from outside, to the ground (earth), thereby protecting electronic equipment from high-voltage It plays a role in protecting electronic equipment from high voltage and destruction by allowing lightning and other high-energy noise from outside to escape to ground (earth).