Emissions Testing Capabilities
Electromagnetic interference (or EMI, also called radio frequency interference or RFI when in high frequency or radio frequency) is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. These effects can range from a simple degradation of data to a total loss of data. The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit.
Emissions testing include the measurement of potential radio frequency interference whether it is radiated or conducted. Limits are established, by the specific governments, to the interference levels based on the expected environments a particular device is used. The requirements for the different marketplaces a product is sold into will determine what kinds of tests and levels are required. The most common markets are North America for FCC and Industry Canada (IC), European Union for CE marking, Japan for VCCI, Korea for KCC marking, Taiwan for BSMI, and Australia and New Zealand for C-Tick marking.
Emission Testing – Radiated and Conducted
Emissions test requirements cover both radiated (air borne) and conducted (down cables).
The many standards which quote these requirements specify the measurement technique and the acceptable limits.
Generally, emissions measurement equipment will include an EMC analyzer together with some form of antenna (for radiated) or ‘transducer’ (for conducted) ancillaries.
Radiated emission is the Radio Frequency (RF) energy produced and unintentionally emitted by a product. The type of equipment you manufacture, and the countries in which you intend to ship, will determine the standard for radiated emissions to which your product must comply.
Some common emissions standards, which include limits for both radiated and conducted interference, are:
- FCC Part 15 for almost all digital devices shipped in the United States
- EN 55022 or CISPR22 for computer equipment sold in Europe for use in a residential or commercial setting. There are many other radiated emissions standards such as
Conducted emissions refer to the RF energy conducted out of a device through its power cord or data line.
Power Line Harmonics and Voltage Flicker
Operation of AC/DC power supplies creates harmonic currents (i.e. currents at frequencies that are multiples of the AC supply frequency of 50Hz or 60Hz). These currents can create problems in electric motors and other electrical devices. Power utility companies in Europe have lobbied for the implementation of standards to limit the amount of harmonic current and voltage devices produce. This has resulted in the IEC/EN61000-3-2 standard, which becomes mandatory in the year 2001 for almost all types of equipment that draw less than 16 amps per phase.
Voltage fluctuations, called Voltage Flicker occur whenever a high current load is switched on or off. A common example of this is the flicker of the lights caused when a household iron or refrigerator switches on.
European Test Standards: EN 61000-3-2 and EN 61000-3-3