INTERNATIONAL  TELECOMMUNICATION  UNION

		     ITU-T RECOMMENDATION SUMMARY


Rec. No. : K.11

Title :	Principles of protection against overvoltages and overcurrents

Study Group : V - Protection against Electromagnetic Effects

Version : Revised

Date of adoption : 1991

Notes :	


Current CCITT documents recognize lightning and faults on nearby 
electrical installations as sources of dangerous disturbances in 
telecommunications lines, which may cause damage leading to 
interruptions in service and the need for repairs or even hazards to 
personnel.

The object of the Recommendation K.11 is to set out principles which 
enable the frequency and seriousness of such disturbances to be 
limited to levels which take account of quality of service, operating 
costs and safety of personnel. These principles are applicable to all 
parts of a telecommunications system.

Recommendation K.11 deals principally with the local exchange, local 
loop plant and subscribers' equipment, but its contents may have wider 
application.

Note - The disturbing phenomena, when they appear, are relatively rare 
or of very brief duration (usually of the order of a fraction of a 
second) and in framing the Recommendation K.11, consideration has not 
been given to methods of avoiding interruption of the functioning of 
equipment during an actual disturbance. The CCITT is pursuing the 
study of such methods.



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