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Each electrical and electronic equipment is in practice exposed to disturbing influences. Disturbance can be classified from different perspectives. Depending on the nature we distinguish: noise, impulse disturbances and transients. In the last decade with the boom in electronics has increased the importance of high frequeny disturbances, which, unlike the low-frequency is easily transmitted, whereas the disturbances ways are harder to define. Electromagnetic compatibility (recompatibility), EMC, is defined as the ability of a device, system or appliance to show the correct operation even in environments, where operate other sources of electromagnetic signals (natural or artificial), while its own "electromagnetic action" does not approach their surroundings, ie. not emit any signals that would disturb other devices.
Disturbance is spreading by means of:
In practise, when sensitive electrical equipment must often operate in environments with strong disturbances, there may often occur very difficult situations. Thus, for example, input logger control computer is connected with the manufacturing technology process through a number of sensors, which often lead to several hundred meters long connection cables carrying low-level signals mV and mA. The cables are often exposed to strong noise disturbing fields capable of inducing voltages into them, reaching tens to hundreds of volts. These spurious signals - pulse or harmonic - can then be evaluated as information received from the technological process and result in improper intervention (often automated) with a potential risk of economic damage, accidents on technical equipment, but also a threat to life or health.
EMI (Electromagnetic Interference) RFI (Radio Frequency Interference) Filters, basically are passive electronic devices that are used to suppress conducted interference that is found on a signal or power line. RFI/EMI Filter will suppress the interference created by other equipment and the interference of the module or system itself, with the desired result being improvement to the immunity from EMI signals in the surrounding setting. RFI/EMI Filters are available in different configurations (Single phase - chassis mountable, PCB mountable, Panel mountable, Three phase - with screw Terminals ,with bus-bar terminals etc).
RFI/EMI Filter works by presenting a significantly higher resistance to higher frequency content. In other words, the low pass design of the RFI/EMI Filter (the combination of shunting capacitors and series inductors) results in the restriction/impeding of the flow of high frequency signals, effectively shorting it to ground. The final result of the RFI/EMI Filter is that it reduces and attenuates the unwanted signal strength, thereby having a minimal effect on other components or devices. Elcom has state of art manufacturing facility. Elcom has a dedicated team in the R&D to provide customized filters as per the applications & customer's requirements.
The protection of equipment from threatening electrical disturbances that occur on the power grid and inside customer facilities and the protection of equipment from conducted disturbances (i.e., emissions) are critical to the life and operation of any electronic equipment. These are two issues for manufacturers that must not be taken lightly. Manufacturers are under continued economic pressure to design and manufacture equipment that must perform as their customer expect. Moreover, manufacturers have profit margins that must be met if they are to satisfy their investors and continue to develop new products for our digital society. Equipment failures and malfunctions caused by EMI problems and voltage surges can be dealt with in an economically effective way without compromising equipment protection or performance.
Two of the technologies that have grown to be commonly used in product design in the last few decades are passive EMI filters using primarily capacitors and inductors and metal oxide varistors (MOVs), respectively.
EMI filters have been used much longer than MOVs. Many new topologies for EMI filters have been designed and implemented. Essentially all of them make use of additional filter components (i.e. capacitors and inductors) to form multi-stage filters. Thousands of new products routinely fail conducted EMI tests when trying to achieve US or international compliance as defined by rules and regulations attempting to avoid EMI problems. Each and every product designer can a “horror story” when trying to achieve EMC compliance. Forensic analyses of many failed products on the market today revealed that product failures were caused by early MOV failure. Many products also suffer from undetectable damage to EMI filters caused by improper or no protection of filter elements from voltage surges.
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