EMI is the short form of Electromagnetic Interference. It is a generalization of an older terminology RFI (Radio Frequency Interference). Electromagnetic Interference can be defined as an electro-static/electro-magnetic disturbance which results in malfunctioning or undesired response in one or more electronic system, equipment or circuit. In this post, we will focus on the different  EMI coupling methods.

To read about EMI in detail, visit http://electricalfundablog.com/blog/what-is-emi/649/.

To read about types of EMI in detail, visit http://electricalfundablog.com/blog/types-of-emi/656/

Ways of EMI Coupling

1.    Conducted EMI :

These type of EMI coupling methods consists unwanted energy flow using conductors (a source and a receiving equipment). One of the frequent and significant route for the flow of conduction current is supply cable.

An example of Conductive EMI

How to contain a Conducted EMI ??

The best way to prevent occurrence of Conducted EMI is by proper designing of an equip and follow up of a good installation procedure which may assist in preventing it. Few of the processes adopted for preventing such EMI are :

  • Use of filters for any interference.
  • Use of shield over cables.
  • Proper grounding of PCBs and cabinet.
  • Maintaining the separation between cables of different signal levels.

2.   Radiated EMI :

When an unwanted signal is transferred from source equipment to victim equipment by radiation through space, It is referred as Radiated EMI.

Could not understand tough words?? Ok, lets understand it in more simpler way. Let us take an example – When an electro-magnetic equipment is operated, It generates a magnetic field which is radiated in space. This magnetic field may cause interference in signal transfer in nearby equipment. If any such incident occurs, it is called Radiated EMI.

An example of Radiated EMI

How to contain Radiated EMI ??

There are two ways to prevent Radiated EMI from occurring. They are:

(i)         Stop the Source equipment from generating undesired radiation : If we can stop the radiation generated by the source just at the beginning point only, then there is no chance for this Radiated EMI to occur. This can be achieved by using shields on the cables. It is less costly and can be carried out with ease.

(ii)        Stop the Victim equipment from receiving undesired radiation : This condition is difficult to achieve as if the interference is in the receiving band of the equipment, then it is extremely hard to prevent it from being received by the Victim equipment. However, proper grounding and filtering of the undesired signal may reduce the affect of Radiated EMI.

 3.   Combination EMI :

These type of EMI coupling methods are manifested by the combination of both conductive and radiation coupling path.

Combination EMI