"EMC" - THE BASICS
Electromagnetic Compatability (EMC), often also referred to as Electromagnetic Interference (EMI), is a crucial aspect to consider when designing electronic products. It ensures that electronic devices and systems function properly and safely in the same electromagnetic environment, without interfering with each other or causing harm to users.
Strict EMC conformity is also often required by product regulations to prevent interference with other devices or systems.
This section aims to help you understand more about what EMC is all about and why it is important.
WHAT IS EMC?
EMC aims to ensure that electrical and electronic products, equipment and systems to function correctly in their intended environment.
All electronic and electrical devices emit electromagnetic interference in some form - EMC involves designing, measuring and testing products to ensure that they comply with the requirements for the local region or territory they are going to be used in.
As well as ensuring compliance, EMC ensures that products don't produce interference that is likely to affect other nearby products and cause harm to people nearby.
WHY IS EMC IMPORTANT?
EMC is important because it is a regulated measure of whether a product or system is suitable to be installed in a specific area, region or territory.
With an ever increasing number of electrical products and systems coming on the market, it is important that there are restrictions on the the levels of electromagnetic noise that can be emitted from a product emissions to make sure that existing equipment continues to operate correctly. It is also a useful measure of a product or system's reliability, ensuring that it can function correctly, safely and reliably in the presence of other electromagnetic disturbances.
HOW TO ACHEIVE EMC COMPLIANCE?
Whilst it is possible to create compliant EMC products and systems by following processes and design guidelines, EMC compliance often requires multiple iterations of pre-compliance testing to ensure that hardware functions correctly whilst ensuring that unintentional emissions are under control.
Good design techniques, such as shielding, signal filtering, and good grounding are often required to ensure that electronic equipment is immune to electromagnetic disturbances, however, sometimes even the best laid plans require some tweaking!
Performing pre-compliance tests on early prototypes helps to reduce the significance of design changes during a project and can help ensure products sail through the compliance test proper. Significant penalties (both financial and time) can affect any project when EMC is not considered early in the design process.
RELEVANT STANDARDS
EMC compliance tests are performed on electronic products or systems to ensure that they comply with the emissions and immunity limits set by regulatory bodies for use in specific areas or regions.
In the UK, electrical products and systems are required to carry a UKCA mark (UK Conformity Assessment) when they are placed on the market. The UKCA marking process requires a product to be tested and assessed against a range of different criteria, from product safety to an in depth look at where the components that make a product have come from and what substances they contain. Products and systems must comply with the overarching SI (Statutory Instrument) for the specific market it is intended to be sold into, however, the EMC requirements for UKCA are covered in Electromagnetic Compatibility Regulations 2016. This regulation sets out the requirements for electromagnetic compatibility in the UK and it defines the emissions and immunity levels that electronic devices, products and systems must comply with to be sold in the UK.
In the EU, there is a similar process in place - CE marking. Just like UKCA, products must meet the requirements of a harmonised standard depending on its target market. These harmonised standards often reference the same underpinning EMC standards. For example:
- CISPR11
- CISPR16
- CISPR22
In the US, the Federal Communications Commission control the regulations for electromagnetic radiation and set the allowable limits. There are a number of codes with which products are required to comply to but the majority of products are required to comply to:
- FCC 47 part 15
These are some of the key organisations responsible for writing and compiling the standards:
- CISPR: The Committee on Special International Committee on Radio Interference is responsible for developing international standards for electromagnetic compatibility.
- IEC: The International Electrotechnical Commission is responsible for developing international standards for electrical and electronic technologies.
- EN: European Norm standards are developed by CENELEC, CEN, ETSI, and are in general harmonized with the international IEC/CSPR standards.
There are many regulations for EMC to ensure that products coming onto the market comply with the requirments in specific areas, regions or terotries.
If you need any help working out what standards you need to comply with, please feel free to get in touch and we can help.
COMMON ACCRONYMS:
- ANSI - American National Standards Institute
- APLAC - Asian Pacific Laboratory Accreditation Cooperation
- BCI - Bulk Current Injection
- CI - Conducted Immunity
- CISPR - Committee on Special International Committee on Radio Interference
- EFT - Electrical Fast Transients
- EMC - Electromagnetic Compatibility
- EMI - Electromagnetic Interference
- ESD - Electrostatic Discharge
- FCC - Federal Communication Commission
- IEC - International Electrotechnical Commission
- RFI - Radio Frequency Interference
- RI - Radiated Immunity
- RES - Radiated Electromagnetic Susceptibility
These abbreviations are commonly used in the field of EMC and are important to understand when working with electronic devices and systems. Knowing these abbreviations can help you understand the different types of electromagnetic disturbances and the regulations and standards that apply to them.
SUMMARY
EMC is an essential aspect of designing and placing electrical products and system on the market. It ensures equipment function correctly and reliably in the presence of electromagnetic disturbances as well as checking to make sure that unintentional emissions are under control.
EMC regulations define limits for emissions and immunity to ensure that electronic devices and systems do not cause harmful interference to other devices and can coexist in the electromagnetic environment.
EMC compliance tests are performed on electronic products to ensure that they comply with the emissions and immunity limits set by regulatory bodies.
STILL UNSURE?
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