EMC 102 — What is EMC?

If you have not yet watched our video EMC 101 - What is EMI? What is RFI? — be sure to watch that first to have a solid foundation for today’s video. Its link is in the description.

Now that you understand EMI, RFI and unwanted electromagnetic noise, we’ll dive into EMC. 

What is EMC?

Electromagnetic Compatibility, or EMC, means all electronic and electromagnetic devices are functioning without issues in their electromagnetic environment. Essentially, EMC keeps our devices from constantly interfering with each other.

In light of potential issues with EMI, EMC compliance is all the more important for minimizing interference and potential downtime for devices.

EMC focuses on two main issues: emission suppression and susceptibility hardening. 

Emission refers to the generation of electromagnetic energy, and EMC aims to provide countermeasures to reduce unwanted emissions. 

Susceptibility is the tendency of electrical equipment to malfunction or breakdown due to unwanted emissions. EMC adds immunity to these disruptions.

In order to suppress emissions, some effective design elements include: 

  • avoiding switching operations, 
  • having different parts of the circuit emit at different frequencies, 
  • keeping noisy circuits separated from the design,
  • and operating at lower signal levels. 

Filters can help power cables and low-frequency signal lines without having to add anything to a PCB layout. Shielding can also be used in conjunction with filtering to act as a barrier (source).

Reducing susceptibility, also known as susceptibility hardening, can be done through additional measures such as:

  • designing for operation at higher signal levels, 
  • transient absorbers, 
  • and error-correction techniques in digital circuitry. 

This can be achieved through capacitors and inductors, which help protect against noise and reduce the ringing waveforms that can be generated by EMI.

EMC issues can come from two sources: internal and external. 

Internal EMC issues come from within a device or its power supply, while external issues come from another device, ambient radio waves or other electrical interference.

EMC is governed by regulatory standards and compliance requirements to ensure devices can function without error. These regulations primarily impact the design of the board layout, filters, inductors, and other relevant parts of a device.

Various EMC regulations mandate a limit of how much noise equipment is allowed to emit over power lines and over the air. Equipment must comply with these limits to be allowed to sell in these markets and industry applications. 

Conducted emissions are measured on the equipment power cord, and radiated emissions are measured in the air around the equipment using an antenna.

Through understanding EMC design, you can minimize unwanted emissions, comply with all internal and external EMC regulations and pass EMC compliance testing the first time.

If your devices need compliance testing or supplies to reduce EMI issues, contact Astrodyne TDI for a custom quote.