EMI stands for electromagnetic interference. It is also called RFI which stands for radio frequency interference. Often EMI and RFI are used interchangeably, however, EMI is actually the frequency of electrical noise, whereas RFI is actually a specific subset of electric noise on the EMI spectrum. RFI is actually a disturbance that affects the electrical circuit due to electromagnetic conduction or electromagnetic radiation that emits from an external source. The disturbance sometimes interrupts, obstruct, and degrades the effective performance of the circuit. Often the source is an object, artificial or natural, that carries rapidly changing electrical currents. There are generally two types of RFI; conducted RFI and radiated RFI. Conducted RFI is the unwanted high frequencies that ride on the a/c waveform, whereas radiated RFI is radiated through the air.

Electro-magnetic compatibility or EMC means that nothing more than an electrical product shall work as intended in its environment. The EMC deals with the problem of noise emission as well as the noise immunity of electronic and electrical products in systems.

Effects of RFI in an Electrical System

You must have experienced interference in your telephone system, flickering in your computer monitors, reliability issues with computer networks, instrumentation errors, or misbehaving of electronics. This is due to the RFI in your electrical environment. RFI can cause problems with your electronics like computers and telephones which can make the workplace difficult to work in. Most machines have controlled electric circuits which make them difficult to control and may become unreliable

How to Mitigate the Effects of RFI

There are many ways to reduce the effects of RFI depending upon your electrical applications. You can choose a large range of RFI filters, chokes, and pulse transformers, for conducted RFI. And for radiated RFI, you should choose from the range of shielding products.

Different Types of RFI Filters

There is a wide variety of RFI filters available. They are mostly available as feed-through components or as PCB filters, IEC filters, and power entry modules, single-phase filters, three-phase filters, etc. Choosing the type of RFI filter depends upon the type of your application.

• Single-phase RFI filters/ 240VAC: There are single phase circuit, two phase circuit, three phase circuit. The range of RFI filters depends upon the electrical systems. The single phase circuit is used for general applications, whereas, The two phase circuit is ideal for applications where higher attenuation is required. For highest possible attenuation, the third state circuit is best.
• Three phase filters-440VAC,480VAC,520VAC,690VAC: This range of RFI filters is often used to attenuate EMI in 440VAC,480VAC OR 520VAC of three phase electrical systems. The common applications used for this filter include variable speed drivers, mining, pumping, refrigeration, industrial, and HVAC.
• Three phase plus neutral filters( 4 wire- 440VAC,480VAC,520VAC): To attenuate EMI in the 690VAC three phase electrical system which requires a neutral connection, this range of RFI filters are used. Applications that are used by this RFI filter include variable speed drivers, mining, pumping, refrigeration, industrial, and HVAC.