How is EMI Different from EMC

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As the electronics industry endeavors to produce more efficient and high-performance gadgets, electromagnetic interference shielding has become the new buzzword among manufacturers. But for people employed in the industry, this is nothing new. In fact, they’ve probably heard the term mentioned casually at the workplace thousands of times alongside phrases like electromagnetic interference and electromagnetic compatibility. And there are plenty of reasons why these words are so commonly used. For starters, these terms are an essential part of the regulatory testing and compliance process for electrical and electronic items. But despite being related closely to one another, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) are hardly the same thing. In fact, there are plenty of differences present between them, which we will discuss below.

How Does EMI Vary from EMC?

Notice how every time you bring your cellphone close to a radio, the latter emits loud crackling noises? That’s because all electronic gadgets generate electrical noise, and this noise interrupts wires and cables, causing issues for connected gadgets. This is EMI – the interference that results from an electromagnetic disturbance affecting the gadget’s performance.

On the other hand, the definition of EMC (Electromagnetic Compatibility) is tied to that of EMI since it refers to how a product would function in its intended environment. The process of determining this feasibility includes testing gadgets to ensure that the EMI emitted is within the permissible limit, and the susceptibility is above a certain threshold so that most complying devices will not disturb it.

Significance of Early EMI and EMC Testing

Companies that develop electrical equipment and electronic products must meet the standard limits of EMI and EMC established by regulatory bodies, before launching the manufactured components in the market. When manufacturers follow the right guidelines during the initial design stages, the product will have no trouble passing the initial EMI/EMC trials. In fact, most manufacturers prefer to use EMI/EMC compliant parts within their design for this purpose. The question is, why all this fuss over choosing the right products in the design stage itself? Why not go back later and work out the kinks after manufacturing is over? Well, the main considerations here are cost and efficiency. If the EMI and EMC compliances are not maintained during the initial phases, then the rework that needs to be carried out is prohibitively expensive for the company, not to mention extremely complicated. This can result in marketing delays and the loss of consumer confidence. Manufacturers cannot afford to waste that kind of time or money on redesigning an electronic item at a later stage.

So What Constitutes a “Bad” EMI and EMC Design?

When a manufacturer fails to take into account the shielding, earthing, and filtering requirements of an electronic device, that is usually an indicator of an inefficient EMI or EMC design. This leads to product failure at the time of testing and compromises the performance and reliability of the product in the real world.

A good product design incorporates the application of the basic EMI and EMC principles, including earthing, effective shielding, and filtering. These processes limit electromagnetic emissions and enhance electromagnetic immunity simultaneously.

Testing Complications

Despite the importance of EMI and EMC testing, there is some confusion regarding the actual process due to differing interpretations of the terms and differing requirements in the EU and the US. Moreover, the products must adhere to certain military or industrial standards, depending upon the target market.

Choosing the Right EMC and EMI Test

It all comes down to the intended application of the device. Important considerations include the usage of the device, how the energy is transferred, and potential interference “victims.” The standard tests are primarily based on conducted and radiated tests.

Considering the importance of EMC and EMI, manufacturers must pay attention to both these aspects while dealing with electronics. As it is rare for electronic products to operate in isolation, the components must be engineered to function properly in the presence of EMI, and this involves the use of electromagnetic interference shielding. Manufacturers use this sort of shielding to make sure their products run without interference and remain free of any operational vulnerabilities.

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