ITU-T K.68 PDF

This Recommendation gives the criteria defining situations to be examined and the installation conditions of both power and telecommunication plants under which the management voltages are applicable to the e.m. interference produced on telecommunication systems by the following power systems:

– a.c. electric power systems;

– d.c. electric power systems;

– a.c. electrified traction systems;

– d.c. electrified traction systems;

resulting from the following physical mechanisms:

– inductive coupling;

– conductive coupling;

– capacitive coupling;

for different power system conditions:

– normal;

– fault;

in the frequency range 0 Hz to 9 kHz.

It covers the resulting effects of:

– danger to people;

– damage to the telecommunication system;

– disturbance to the telecommunication system (malfunction, noise).

This Recommendation is applicable to all telecommunication lines with metallic elements. Fibre-optic cables are to be considered only if a metal conductor, screen or sheath, is included in their construction.

The objective of this Recommendation is to establish:

– the procedure for evaluating the e.m. interference (clause 4);

– the maximum distance between power and telecommunication plants for studying the e.m. interference between them (clause 5);

– the installation conditions (clause 7) of both power and telecommunication plants under which the interference results shall be evaluated (through calculations in accordance with volume II or III of the Directives, through measurements, or through a suitable combination of both) in order to check the compliance (clause 8) of the induced voltages on the telecommunication line with the appropriate management voltages (clause 6);

– an official agreement between telecommunication operators and electric power and electrified railway operators in order to clearly share responsibilities and, as a consequence, if necessary, the relevant expenses for mitigation measures (clause 9);

– a reminder of the need to maintain a suitable monitoring of the technical characteristics evolution of the plants involved in the interference to avoid, due to modifications, an acceptable interference evolving into an unacceptable one (clause 10).

This Recommendation is applicable to all situations where a private or public telecommunication plant is liable to be influenced by one or more power plants.

This Recommendation is applicable to new telecommunication and new power plants and also to existing plants where modifications are proposed, such as changes of system earthing, line configuration, operating voltage and fault current (also due to modifications in plants connected to another under consideration), which will significantly increase the existing levels of e.m. interference.

This Recommendation shall be used in the determination of the types of coupling to be considered for various power system operating conditions, and in the comparison of predicted induced voltages with the management voltages given in clause 6.

This Recommendation does not apply to e.m. interference from electric power systems with a nominal operating voltage below 1 kV.

The definition of the mitigation measures, if necessary, is outside the scope of this Recommendation.