How an EMI Filter Works

Introduction

Electromagnetic Interference (popularly known as EMI) can be defined as the interference caused due to the electric or magnetic field that affects (degrades or damages) the signal strength, the component, and the functionality of the electrical device. It encompasses RF (Radio Frequency) interference.

EMI can be classified into two broad areas, namely Narrowband emission and Broadband emission. Narrowband emission is generally man-made whereas broadband emission may be either natural or man-made. As the name suggests, narrowband emission is only limited to a small area of the radio spectrum, while broadband emission affects a large area of the electromagnetic spectrum. Narrowband emission may be continuous or sporadic, whereas broadband emission is a one-time event that is random, sporadic, or continuous. Power lines generate hum sound (i.e., narrowband emission), while lightning strikes generate broadband emission.

EMI Sources



Electromagnetic interference can be caused in various ways. Interference produced within an electrical device may be due to impedance, interconnected wiring, opposition to current, or voltage difference between conductors.

EMI can also be produced externally by cosmic energy (such as appliances and power cords, solar flares, and power lines).

A significant amount of electromagnetic interference is produced in power lines that get carried to the equipment. Therefore, to eliminate the interference, EMI filters are designed that can either be used as a device or an internal module.

EMI can often manifest itself in ways that are hard to detect, so it is difficult to diagnose electromagnetic radiation. One can perform tests for weeks or months without realizing that EMI is degrading the accuracy of measurements. Once an issue is detected, it will be difficult to distinguish EMI from other sources of noise. A person will require to walk through the process of troubleshooting before diagnosing an EMI issue correctly.

EMI sources can often be distant from the installation point as EMI is caused by the electromagnetic field, i.e., it can stretch across rooms and through buildings.

EMI Filters & its Working

EMI filter is a device that is used to suppress or eliminate electromagnetic interference. Generally, electromagnetic noise or EMI has a high-frequency. To suppress this noise, both capacitors and inductors are used together in an EMI filter. Since the capacitor eliminates the direct current (DC) and allows alternating current (AC) to pass through it, therefore, the electromagnetic interference is carried into the electrical device. Inductor eliminates the AC and allows the DC to pass through it, thereby reducing the interference level to zero (i.e., ground or shorting).

EMI filter uses the capacitor in shunt and inductor in series. The shunt capacitor redirects the high-frequency current (or interference) to multiple inductors connected in series. As the high-frequency current passes through each inductor, the overall voltage of the signal gets reduced. Hence, electromagnetic interference gets optimally reduced to zero.

EMI filters can be widely used in different applications and can be found in different electrical and electronic devices or equipment such as computers, lab equipment, medical equipment, radio equipment, and military equipment.

From single phase EMI filters, three phase EMI filters to infinite custom capabilities, Premier Filters can design and manufacture EMI power line filters. It delivers unparalleled products and services to its clients according to their business requirements. Want to buy EMI filters that best suit your project requirements? Call 657-226-0091 x702 or email at info@premieremc.com. 

Location: California, USA

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