The measurement standards (EN 55011 or EN 55022) involve a LIS and a faraday chamber. The Device Under Test is supplied
via filters and LISN and measurement of conducted noise is achieved using a spectrum analyser (or EM receiver) plugged
into the LISN.
The EN 55011 standard applies for products belonging to limits and methods of measurement of radio disturbance
characteristics of Industrial, Scientific and Medical (ISM) radio-frequency equipment. It is the reference standard for the
generic standard for industrial environments.
Two groups and two classes are distinguished :
- Group 1 : All ISM apparatus in this group use or generate intentionally electrical energy on the main cables in the
RF range (10kHz - 30MHz), because it is necessary for the internal working of the device.
- Group 2 : All ISM apparatus uses or generated intentionally radiated electrical energy in the RF range (10kHz - 30MHz),
in order to act on matter. Electro-erosion apparatus belong to this group too.
- Class A : Apparatus in this class is used in other locations, such as domestic areas. Moreover, they should not be
connected directly to an electrical distribution network feeding domestic areas.
- Class B : On the contrary, apparatus in this class are used in domestic areas or are
connected directly to an electrical distribution network feeding domestic areas.
EN 55011 Standard
| Frequency |
Max Level for Class A apparatus (db microV) |
Max level for Class B apparatus (dB microV) |
| Group 1 |
Group 2 |
Group 1&2 |
| Quasi Peak |
Mean |
Quasi peak |
Mean |
Quasi peak |
Mean |
| 0.15 to 0.5 |
79 |
66 |
100 |
90 |
66 to 56
decreasing with Log (Freq.) |
56 to 46
decreasing with Log (Freq.) |
| 0.5 to 5 |
73 |
60 |
86 |
76 |
56 |
46 |
| 5 to 30 |
73 |
60 |
90 to 70
decreasing with Log (Freq.) |
80 to 60
decreasing with Log (Freq.) |
60 |
50 |
|