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What is the difference between EMI and EMC?

The terms Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) are often used interchangeably when referring to regulatory testing of electronic components and consumer goods. Because they are related in so many ways, it is easy to confuse the two.

Interferência eletromagnética (EMI)
What is the difference between EMI and EMC?

In this article, we try to demystify EMI and EMC and provide a basic overview of the types of test equipment employed and their requirements in each area.

Test bench
Any electronic device generates a certain amount of electromagnetic radiation. We think of electronics as closed systems, but the electricity that flows through circuits and wires is never fully contained. Such energy may be propagated by air as electromagnetic radiation and / or conducted along (or coupled) to I / O interconnection or power cables, which is typically referred to as disturbing voltages.

Testing requirements for EMI and EMC can be quite complex, with a wide range of industry and application-specific implications to consider when placing a product on the market.

What is EMC?

EMC is a measure of a device’s ability to operate as intended in its shared operating environment, while at the same time not affecting the ability of other equipment within the same environment to operate as intended. Assessing how a device will react when exposed to electromagnetic energy is a component of this, known as immunity (or susceptibility) testing. Measuring the amount of EMI generated by the device’s internal electrical systems is a process known as emission testing.
Both aspects of EMC are important design and engineering considerations in any system. Failure to properly anticipate a device’s EMC can have several negative consequences, including security risks, product failure, and data loss. As a result, a wide range of EMC and EMI test equipment has been developed to provide engineers with a clearer view of how a device will operate under real conditions.

Measuring and monitoring EMC?

Emissions testing requires the use of EMI measurement equipment such as receiving antennas, amplifiers and spectrum analyzers. Working together, these tools provide an accurate measurement of the amount and type of noise generated by a device. This can be done in an open area test site or in a shielded, anechoic (or semi-anechoic) test chamber.

Immunity (or susceptibility) testing involves determining a device’s ability to tolerate noise from external sources. This requires tools that can simulate and measure specific frequencies of electromagnetic energy. EMC test equipment can be used to subject a device to electromagnetic noise at various frequencies, to simulate a power surge, or to evaluate the effectiveness of a device’s power supply. Ultimately, the nature of the device, its intended application, and any regulatory requirements will determine what type of test equipment is required.

Regulatory Guidelines for EMC Testing

The FCC Part 15 rules set limits on the amount of unlicensed radio frequency interference that may be produced by consumer electronics and other devices.
MIL-STD 461 and MIL-STD 464, which describe EMC and environmental requirements for components / subsystems and systems for military applications.
Outside the US, various ISO, IEC, CISPR, and other standards set acceptable limits for EMI and general EMC. In some sectors and markets, compliance with these standards is voluntary. In others, it is a requirement.

EMI and EMC Test Products

Pre-compliance EMC testing is widely recognized as one of the best ways to identify EMC issues early in the product development cycle. Com-Power Corp. manufactures a wide range of EMI and EMC testing equipment. If you plan to do internal EMC testing, we can help. Visit our site to browse our inventory of antennas, comb generators, analyzers and more.

Source: Translated Com-Power Corporation

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