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What Are EMI Power Line Filters and What is Their Importance?

Electromagnetic interference (EMI) refers to instances where undesirable electric currents interrupt or adversely affect the current that a particular electronic device is supposed to receive. These disruptions come in the form of electromagnetic noise, that of which may be externally sourced or caused by other components located within the device. Depending on the magnitude of EMI, the disruption can range from poor signal reception to outright component malfunctions and failure. In countless electrical systems and devices, it is important to have protection against EMI in order to maintain optimal operating conditions. In this blog, we will discuss EMI power line filters, allowing you to better understand how protection is upheld.

Within various settings, EMI filters are a requirement as a result of the high frequency switching techniques that are carried out in many power conversion circuits. As Switch Mode Power Supplies (SMPS), rectifiers, inverters, and other related components cause harmonic noise due to rapid voltage and current changes, EMI filters are necessary to meet conducted emission requirements as dictated by international and military EMI standards alike. EMI power line filters are also beneficial for the means of reducing noise that may already be present within the power distribution system.

During the installation of an EMI power line filter, there are various issues that one should be aware of in order to uphold the effectiveness of the device. When adding the EMI filter to various equipment, it is crucial that the filter’s metal case is bonded to the metal case or chassis of the equipment itself through metal-to-metal bonding. It is also important to remove any non-conductive surfaces or painted materials so that the overall effectiveness of line to ground capacitors is maintained.

The filter must also be strategically placed at the entry point of incoming power lines. With proper placement, the filter can ensure high performance and shield integrity. As the filter is moved further away from the power entry point, the more likely it is for noise to radiate from the power supply or logic circuits. This noise can then couple onto the power lines, bypassing the filter and making it fairly useless.

The last major concern during installation is to have proper system cable routing. Generally, incoming power lines to the filter should be isolated from any other cables and wires that are present within the assembly. If cables are too close to one another, noise will couple on the filter wires, thus bypassing the filter. As such, one should follow manufacturer specifications or recommendations to ensure proper installation and assembly of all parts.

EMI power line filters can come in numerous types, allowing for many applications to benefit from their use. Generally, EMI power line filters find implementation within modems, computers, digital test equipment, surge protection devices, microprocessors, linear power supplies, hard-disk systems, and so much more. If you have sensitive electronic devices or systems that require protection from electromagnetic interference, look no further than ASAP Global Supplies for all your EMI power line filter needs.

ASAP Global Supplies is a website owned and operated by ASAP Semiconductor, and we are a leading parts distributor with over 2 billion new, used, obsolete, and hard-to-find items readily available for purchase. As you explore our expansive part catalogs, we invite you to request quotes on items that you are interested in for your comparisons. With AS9120B, ISO 9001:2015, and FAA AC 00-56B certification and accreditation, we guarantee the quality and caliber of our products. If you would like to learn more about our services or wish to initiate the purchasing process, give our team members a call or email at your earliest convenience, and they would be more than happy to assist you however they can.


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