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ITU-T K.21 (11/2011)

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Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents
Recommendation ITU-T K.21 specifies resistibility requirements and test procedures for telecommunication equipment that is installed in or on a customer's premises.

Overvoltages or overcurrents covered by this Recommendation include surges due to lightning on or near the line plant, short-term induction from adjacent a.c. power lines or railway systems, earth potential rise due to power faults, direct contacts between telecommunication lines and power lines and electrostatic discharges. The sources for overvoltages in internal lines are mainly inductive coupling caused by lightning currents being conducted in nearby lightning strokes or lightning currents being conducted in nearby conductors.

Major changes compared with the 2008 version of this Recommendation include:
• updating the references;
• information on what USB ports should be tested;
• information on when to add protection to untested ports;
• adding test requirements for external coaxial cable ports;
• adding test requirements for multiple conductor internal unshielded cable ports.
Citation: http://handle.itu.int/11.1002/1000/11421
Approval date: 2011-11-13
Provisional name:K.y
Approval process:AAP
Status: In force
Maintenance responsibility: ITU-T Study Group 5
Further details: Patent statement(s)
Development history
[9 related work items in progress]
Ed. ITU-T Recommendation Status Summary Table of Contents Download
6 K.21 (11/2011) In force
here
here
here
6.0 K.21 (2011) Erratum 1 (05/2014) In force - - here
5 K.21 (04/2008) Superseded
here
here
here
5.0 K.21 (2008) Erratum 1 (05/2008) Superseded - - here
4 K.21 (07/2003) Superseded
here
here
here
4.0 K.21 (2003) Erratum 1 (01/2004) Superseded - - here
3 K.21 (10/2000) Superseded
here
here
here
2 K.21 (10/1996) Superseded
here
here
here
1 K.21 (11/1988) Superseded -
here
here