Conducted radio frequency emissions

The test aims to determine the magnitude of the disturbance voltage (conducted RF emission) emitted on the power line, or data lines, which may interfere with other devices connected to the same power or data network. The propagation of the disturbance through conduction occurs through the power cable or other connecting cables between different systems. Due to their more or less significant capacitance, the cutoff frequencies of these lines are relatively low, so the lower frequency components propagate over a certain distance primarily; for this reason, the disturbance produced by the tested equipment is measured up to a frequency of 30MHz.
Measurements on cables other than the power cable are only provided for certain types of devices (e.g., household appliances, lighting devices, information technology).
The measurement is practically applicable to almost all electrical and electronic devices.

emissioni condotte radiofrequenza

The measurement of conducted RF emissions is performed by inserting an artificial network or, for higher currents and load conductors, using a voltage probe between the power supply network and the device under test; the measurement carried out with the LISN (Line Impedance Stabilization Network) ensures better reproducibility and traceability to the standard limits.

The purpose of the LISN is twofold:

  • To present a constant impedance (50Ω) between the phase conductor and the ground wire and between the neutral conductor and the ground conductor across the entire measurement frequency range;
  • To prevent external conducted disturbances from the power supply network from contaminating the measurement.

For data cables, the LISN is replaced by an AAN (Asymmetric artificial network), positioned between the Equipment Under Test (EUT) and the Auxiliary Equipment (AE) responsible for measuring common-mode conducted disturbances. An AAN is generally used to measure conducted emissions on Ethernet ports or other telecommunication lines.

The standards to be applied are:

EN 55016-2-1
Specifications for radio disturbance and immunity measuring apparatus and methods - Part 2-1: Methods of measurement of disturbances and immunity - Conducted disturbance measurements.
This standard specifies the test methodology and instrumentation to be used.

Then there are specific product standards depending on the EUT, such as:

EN 55032
Electromagnetic compatibility of multimedia equipment - Emission Requirements

EN 55011
Industrial, scientific and medical (ISM) equipment - Radio disturbance characteristics - Limits and methods of measurement

EN 55014-1
Electromagnetic compatibility - Requirements for household appliances, electric tools, and similar apparatus. Part 1: Emission

Or specific environmental standards to be applied in the absence of a product standard:

EN 61000-6-3
Electromagnetic compatibility (EMC). Part 6-3: Generic standards - Emission for residential, commercial, and light industry environments

EN 61000-6-4
Electromagnetic compatibility (EMC). Part 6-4: Generic standards - Emission for industrial environments

EN 61000-6-8
Electromagnetic compatibility (EMC). Part 6-8: Generic standards - Emission standard for professional equipment intended for commercial and light industry environments