Electromagnetic Compatibility: EMC

Electromagnetic Compatibility: EMC

It is the ability of a team or system not to cause electromagnetic interference to other equipment, and, at the same time, to function correctly in the face of disturbances that other systems may cause, within their work environment.

The electromagnetic compatibility is summarized in two concepts:

  • EMI: ElectroMagnetic Interference (EMISIONS)
  • EMS: ElectroMagnetic Susceptibility (INMUNITY) 
  1. Electromagnetic waves and compatibility
  2. Type of EMC Phenomena and their elements
  3. Types and definition of standars
  4. Requirements military and civil areas

The origin of electromagnetic waves can be of industrial or natural origin and in turn can be intentional or unintentional:


  • Broadcasting and TV broadcasters
  • Mobile telephony
  • Radars ….

Example of unintended:

  • Ray
  • Variators (speed, frequency)
  • Contactors, relays …

Importance of electromagnetic compatibility

Among the main causes of the importance of electromagnetic compatibility can be highlighted:

  • Increase of electronic equipment both in industry and at home.
  • Larger and more complex equipment
  • Increase in telecommunications systems (Radio, mobile, etc.).
  • New working frequencies of the equipment.

  1. EMISSION: Level of electromagnetic interference that an electrical or electronic device introduces into the environment as a result of its operation
  2. INMUNITY: A device’s ability to function properly in an environment with a level of electromagnetic disturbance

In both cases, the electromagnetic disturbances can be RADIATED, if their means of propagation is air, or DRIVES, if their means of propagation are the cables.

Elements of an electromagnetic phenomenon

Interference generator; Coupling path; Receptor

Therefore, when an EMC problem appears, the alternatives go through:
EMISSION: Suprimir la interferencia en la fuente.

EMISSION & IMMUNITY: Make the coupling path ineffective.

IMMUNITY: Make the receiver less sensitive to interference.

  • Military and Civil
  • European: EN, ETSI
  • Nationals: UNE-EN, BS, NF, VDE, ANSI, VCCI
  • Basic Standards
  • Generic Standards
  • Product Rules
  • Product Family Standards

To understand what is defined in each rule, here is a brief definition of each of them.

  • BASIC RULES: They define the test methods. The limits to be met and the test levels to apply, with some exceptions, are usually indicative.
  • GENERIC NORMS: They are applied in the absence of an appropriate product / product family standard to the equipment or system. Otherwise they follow the same methodology as the product norms / family of products.
  • PRODUCT RULES / PRODUCT FAMILY: They define the limits to be met and the test levels to be applied. Reference to the basic standards regarding the test procedure.

  • Conducted Emissions Cable Power
  • Susceptibility Driven Power Cable
  • Conducted Emissions Cable Interconnection
  • Conducted Susceptibility Cable Interconnection
  • Conducted Emissions Antenna Driver
  • Conducted Susceptibility Antenna Driver
  • Emission: Coupling by ground impedance
  • Susceptibility: Coupling in ground impedance
  • Radiated Magnetic Field and Radiated Electric Field
  • Susceptibility to Magnetic Field and Susceptibility to Electric Field

Civil area requirements

  • Radiated Emissions
  • Conducted emissions
  • Harmonics
  • Flicker / Flicker
  • Radiated Susceptibility
  • ESD (Electrostatic Discharge)
  • Electrical Transients (EFT / Bursts)
  • Surges
  • Susceptibility Driven
  • Gaps, interruptions and voltage variations

This post is also available in: Spanish

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