CLC/TR 50481:2009

SLOVENSKI STANDARD
01-september-2009
1DGRPHãþD
SIST CLC/R 210-004:2000
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Recommendations on filters for shielded enclosures
Ta slovenski standard je istoveten z: CLC/TR 50481:2009
ICS:
31.160 (OHNWULþQLILOWUL Electric filters
33.100.10 Emisija Emission
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CLC/TR 50481
RAPPORT TECHNIQUE
April 2009
TECHNISCHER BERICHT
ICS 33.100.10; 31.160 Supersedes R210-004:1999

English version
Recommendations on filters for shielded enclosures

This Technical Report was approved by CENELEC on 2009-03-20.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: avenue Marnix 17, B - 1000 Brussels

© 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. CLC/TR 50481:2009 E
Foreword
This Technical Report was prepared by the Technical Committee CENELEC TC 210, Electromagnetic
compatibility (EMC).
The text of the draft was submitted to vote in accordance with the Internal Regulations, Part 2,
Subclause 11.4.3.2 (simple majority) and was approved by CENELEC as CLC/TR 50481 on
2009-03-20.
This document supersedes R210-004:1999.
________________
– 3 – CLC/TR 50481:2009
Contents
1 Scope . 4
2 Normative references . 4
3 Definitions . 4
4 General recommendations on filters . 4
5 Insertion loss . 4
5.1 Insertion loss of filters . 4
5.2 Insertion loss values . 5
6 Filter selection . 5
6.1 Choice of filter . 5
6.2 Power line filters . 6
6.3 Signal line filters (including telecom lines) . 6
7 Electrical safety. 6
8 Installation of filters . 7

Figures
Figure 1 – Filter insertion loss value a (typical performance for shielded enclosures) . 5
e
Figure 2 – Filter installations schematic . 7

1 Scope
This document was prepared to give users general advices on filtering solutions adopted in
shielded enclosures. It is mainly a collection of hints derived from practical experience.
This document is coordinated with EN 50147-1 and EN 50417-2.
The document covers the frequency range DC to 40 GHz. The range above 40 GHz and up to
400 GHz is under consideration.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60050(161), International Electrotechnical Vocabulary (IEV) – Chapter 161:
Electromagnetic compatibility
CISPR 17:1981, Methods of measurement of the suppression characteristics of passive radio
interference filters and suppression components
3 Definitions
For the purposes of this document, the terms and definitions given in CISPR 17:1981 apply.
4 General recommendations on filters
To prevent interference or over-voltages from being fed into, or out of the shielded enclosure
via lines, all lines passing through the shielding must be filtered. In many cases it is not only
necessary to protect equipment from broadband interfering signals, but also to limit pulsed
type interference (effects of lighting and any man made pulse type phenomena e.g. industrial
process). The filter shall not degrade the shielding attenuation of the shielded enclosure.
Filters that meet the requirements of the referenced specification below should not be
retested after installation because the testing of filters is done in 50 Ω system and shielding is
a measure of transmission loss performed with antennas. If cables that penetrate a shielded
enclosure cannot be filtered, they shall have adequate shielding effectiveness and termination
on both sides so as to avoid degradation of the shielding effectiveness of the whole
installation.
Filters are required at each point where an unshielded wire or cable passes through the
shielding material of a shielded enclosure. This is to prevent uncontrolled transfer of
electromagnetic energy into, or out of,
...