Overview: Electro-Magnetic Compatibility (EMC)

emc compliance testing lab facility

Electromagnetic Compatibility (EMC) is a term used to describe how a device performs in an environment of electromagnetic noise. EMC includes two factors — a device's tolerance to emissions (noise immunity) and how much emission it produces. The goal is to limit the unintentional generation, propagation and reception of electromagnetic energy. EMC is characterised by several aspects.

  • Identify the character of the EMI threat
  • Set emission limits for your equipment
  • Set levels of susceptibility from surrounding equipment
  • Test for various standards compliance as prescribed by the application

What is the main difference between EMI and EMC?

EMI refers to the phenomenon of electromagnetic radiation, when the emission interferes with electronic components and RF systems. We commonly use dB as a unit of EMI noise measurement.

EMC is a term that describes how well a device blocks or withstands EMI. The ability of an equipment to operate in an environment where EMI is present is a measure of its EM Compatibility.

What is EMC Testing and what are the effects of it?

EMI is not a directly visible phenomenon and is highly dependent on the installation site and surrounding equipment. So manufacturers cannot easily gauge if their products are electromagnetically compatible. The only real way to find out is to conduct scientific EMC Tests. They are performed with a production model, and often repeated post-production, onsite to ensure compliance is maintained following changes in the production. OEM parts and accessories should come with a Declaration of Conformity and be checked for compatibility with the final product's intended use.

EMC Testing is the only way to prevent ill-effects of electromagnetic noise, such as equipment damage, energy wastage or increase in maintenance costs. Several well published industrial products have been recalled or withdrawn from the market because electromagnetic compatibility and EMC Testing was not fully considered. Failing to meet EMC and RF regulations can deny equipment manufactures entry into export markets which have stringent EMI/EMC compliance standards.

What are the different types of EMC tests?

Electromagnetic Compliance Testing can be categorised into several types depending on the particular stage of the product life cycle in which it is performed.

Development EMC test - When the electronic circuit design is still in progress, it is easy to make alterations to the design. So informal EMC testing is carried out to roughly estimate the EMI levels of the various components. The circuit design and EMC filters can be quickly adjusted accordingly.

Pre-compliance EMC test - When a representative prototype of the product is ready, preliminary compliance testing of the product is performed in the controlled lab environment.

EMC Compliance Test - A series of mandatory EMC compliance tests are conducted depending on the nature of the product and the market it is intended for. Defence and medical applications may have their own specific tests. Export oriented compliance such as CE marking also requires a specific set of compliances. The EMC compliance test categories are further divided as follows:

Emission Testing

  • Conducted Emissions
  • Radiated Emissions

Immunity Testing

  • Conducted Immunity Testing
  • Radiated Immunity Testing
  • Transient Immunity Testing :
    • Surge Immunity Testing
    • ESD (Electro Static Discharge) Immunity Testing
    • Electrical Fast Transient (EFT) / Burst testing

How to choose the right EMC testing Lab?

EMI/EMC tests are conducted in specialized and accredited test facilities. These tests involve test methods, equipment and measurement sites in compliance with national or international standards. Outcome of testing is to certify that a device meets the required standards. Compliance with national or international standards is defined by individual nations. Compliance tests are commonly done prior to production of a device.

Testing is typically divided into two categories: Emissions testing and Immunity testing .

Emissions testing : Measures RF emissions, both radiated and conducted, of a device or Equipment Under Test (EUT). Certifies that emissions levels do not exceed the limits defined by the appropriate standard.

Immunity testing : RF energy is transmitted onto a device or Equipment Under Test (EUT) to verify if the EUT operates correctly and without fault while under such an environment, according to the appropriate standard.

Open-air test sites (OATS) are the reference sites used for most standards. They are especially used for emissions testing of large equipment systems. However, RF testing of a physical prototype is more often carried out indoors, in a specialized EMC test lab chamber . Different type of test chambers include anechoic, reverberation and the gigahertz transverse electromagnetic cell (GTEM cell).

EMI/EMC Compliance standards and Specifications

A number of different EMC standards, each with their own requirements related to test set-up, power levels, frequencies, and many other details, have been developed over time. Different standards have been adopted by different nations, with some standards designed for harsh military requirements, while others are intended for a benign suburban environment.

European Union - CE Marking

Governing bodies in the European Union with respect to EMC include the IEC, CISPR, and the European Committee for Electro-technical Standardization (CENELEC). The IEC coordinates international standardization and related matters, while CENELEC and CISPR are largely responsible for approving detailed EMC standards to demonstrate compliance with the EMC Directive. Products sold in the European Union must be in compliance with EMC Directive, 89/392/EEC. Products that meet the EMC directive carry the "CE" mark that signifies the manufacturer's assertion of compliance.

USA - MIL-STD military standards and compliance

MIL-STD (latest being MIL-STD-461F issued in December 2008) defined by the Department of Defence, USA is a system-level standard that specifies EMC requirements and limits. It consists of EMC requirements, EMC test set-up and methodology and EMC definitions and acronyms.

It is based on the operational platform for deployment (surface, ships, aircraft, etc.) and location on that platform (internal or external). The overall requirement is comprised of eighteen sub-tests that cover diverse system characteristics ranging from emissions conducted via power leads to spurious and harmonic radiated emissions.

This testing is not inexpensive and is quite elaborate. The five core tests (RS103, RE102, CS101, CS114 and CS116) will require roughly two days of lab time; the entire standard, seven to ten days.

MIL-STD-461F Subtests

  • CE101 Conducted Emissions, Power Leads, 30 Hz to 10 kHz
  • CE102 Conducted Emissions, Power Leads, 10 kHz to 10 MHz
  • CE106 Conducted Emissions, Antenna Terminal, 10 kHz to 40 GHz
  • CS101 Conducted Susceptibility, Power Leads, 30 Hz to 150 kHz
  • CS103 Conducted Susceptibility, Antenna Port, Intermodulation, 15 kHz to 10 GHz
  • CS104 Conducted Susceptibility, Antenna Port, Rejection of Undesired Signals, 30 Hz to 20 GHz 
  • CS105 Conducted Susceptibility, Antenna Port, Cross-Modulation, 30 Hz to 20 GHz 
  • CS106 Conducted Susceptibility, Transients, Power Leads
  • CS109 Conducted Susceptibility, Structure Current, 60 Hz to 100 kHz
  • CS114 Conducted Susceptibility, Bulk Cable Injection, 10 kHz to 200 MHz
  • CS115 Conducted Susceptibility, Bulk Cable Injection, Impulse Excitation
  • CS116 Conducted Susceptibility, Damped Sinusoidal Transients, Cables and Power Leads, 10 kHz to 100 MHz
  • RE101 Radiated Emissions, Magnetic Field, 30 Hz to 100 kHz (Radiated emissions from equipment and subsystem enclosures, including electrical cable interfaces)
  • RE102 Radiated Emissions, Electric Field, 10 kHz to 18 GHz (Radiated emissions from equipment and subsystem enclosures, all interconnecting cables, and antennas designed to be permanently mounted to EUTs)
  • RE103 Radiated Emissions, Antenna Spurious and Harmonic Outputs, 10 kHz to 40 GHz
  • RS101 Radiated Susceptibility, Magnetic Field, 30 Hz to 100 kHz (Applicable to equipment and subsystem enclosures, including electrical cable interfaces)
  • RS103 Radiated Susceptibility, Electric Field, 2 MHz to 40 GHz (Applicable to equipment and subsystem enclosures and all interconnecting cables)
  • RS105 Radiated Susceptibility, Transient Electromagnetic Field

How to choose the right power line EMI/EMC filter?

The right choice for the EMI filter depends on several factors governing the product to be protected and the installed environment.

Noise path - EMI noise may reach the equipment through a conducted or radiated path.
Industry - Such as Defence, healthcare, consumer appliances, industrial automation, IT & telecom.

Type of compliance - Immunity or emission test compliance, safeguard against transient noise are some of the compliance types.

EMI Filters for High Frequency Electromagnetic noise

What EMIS Offers

EMISINDIA is a trusted name when it comes to EMC testing and consultancy services . Our expert engineering and consulting team provide support to design, plan, execute, inspect and verify EMC compliance systems. EMIS can help customers with their products to meet International EMI/EMC standard compliance by providing suitable solutions within a short time span.

Our test facility is Inhouse testing facility or lab for EMC testing in accordance with the standard ISO/IEC 17025:2017. We also support on-site testing in compliance with international standards. EMIS also has a DSIR (Department of Scientific and Industrial Research, Government of India) recognised R&D Lab where customers can avail a wide range of military compliance safety testing services.

Customers can avail of the following testing services offered by EMIS:

  • EMI/EMC Compliance Testing
  • Support for equipment to qualify for CE Marking
  • MIL standards and other international standards compliance
  • Commercial and Military Standards compliance
  • Conducted and Radiated Emissions Testing
  • Immunity Testing
  • Consumer Electronics, Aviation, Defence, Medical Electronics and Telecommunication industry applications
For our full range of EMI/EMC Testing and Consultancy services, please refer