Rec. ITU-T K.98 Corrigendum 2 (06/2020) Overvoltage protection guide for telecommunication equipment installed in customer premises
Summary
History
FOREWORD
Table of Contents
1 Scope
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Recommendation
4 Abbreviations and acronyms
5 Conventions
6 Factors influencing surge levels
     6.1 Surge coupling and mechanisms of damage
          6.1.1 Flashes to a structure (S1)
          6.1.2 Flashes near a structure (S2)
          6.1.3 Flashes to a line (S3)
          6.1.4 Flashes near a line (S4)
          6.1.5 Impact of actual installations
     6.2 Elements of protection
     6.3 Equipment resistibility
          6.3.1 Resistibility levels
          6.3.2 Port types
          6.3.3 SPDs versus insulation
     6.4 Correct classification and use of ports
     6.5 Cable routing
     6.6 Earthing and bonding
     6.7 SPDs
          6.7.1 General
          6.7.2 Location
          6.7.3 Rating
               6.7.3.1 Level of protection
                    6.7.3.1.1 Strike to the structure
                    6.7.3.1.2 Strikes to earth near a structure
                    6.7.3.1.3 Strike to the services near to the structure
                    6.7.3.1.4 Strike to the services remote from the structure
                    6.7.3.1.5 Strikes near to the services
                    6.7.3.1.6 Choice of protection levels
     6.8 Direct strike protection of a structure
     6.9 Installation of protection
          6.9.1 Philosophy of protection
          6.9.2 Risk Assessment
          6.9.3 Waveform at downstream SPDs and coordination between SPDs
          6.9.4 Protection of ports
               6.9.4.1 External telecommunication ports
               6.9.4.2 Mains ports
               6.9.4.3 Telecommunication antenna ports
               6.9.4.4 Internal ports
          6.9.5 Installation of MSPDs
          6.9.6 Installation of primary protection SPDs
     6.10 Conclusions
     A.1 Introduction
     A.2 Stress applied to the equipment via the mains port
          A.2.1 TN-S power system
               A.2.1.1 Earthed equipment
                    A.2.1.1.1 Without primary protection
                    A.2.1.1.2 With primary protection
               A.2.1.2 Floating equipment
                    A.2.1.2.1 Without primary protection
                    A.2.1.2.2 With primary protection
          A.2.2 TN-C and TN-C-S power systems
               A.2.2.1 Earthed equipment
                    A.2.2.1.1 Without primary protection
                    A.2.2.1.2 With primary protection
               A.2.2.2 Floating equipment
                    A.2.2.2.1 Without primary protection
                    A.2.2.2.2 With primary protection
          A.2.3 TT and IT power systems
               A.2.3.1 Earthed equipment
                    A.2.3.1.1 Without primary protection
                    A.2.3.1.2 With primary protection
               A.2.3.2 Floating equipment
                    A.2.3.2.1 Without primary protection
                    A.2.3.2.2 With primary protection
     A.3 Stress applied to the equipment via the telecommunication port
          A.3.1 TN-S power system
               A.3.1.1 Earthed equipment
                    A.3.1.1.1 Without primary protection
                    A.3.1.1.2 With primary protection
               A.3.1.2 Floating equipment
                    A.3.1.2.1 Without primary protection
                    A.3.1.2.2 With primary protection
          A.3.2 TN-C and TN-C-S power systems
               A.3.2.1 Earthed equipment
                    A.3.2.1.1 Without primary protection
                    A.3.2.1.2 With primary protection
               A.3.2.2 Floating equipment
                    A.3.2.2.1 Without primary protection
                    A.3.2.2.2 With primary protection
          A.3.3 TT and IT power systems
               A.3.3.1 Earthed equipment
                    A.3.3.1.1 Without primary protection
                    A.3.3.1.2 With primary protection
               A.3.3.2 Floating equipment
                    A.3.3.2.1 Without primary protection
                    A.3.3.2.2 With primary protection
     A.4 Waveform after primary protection and coordination
          A.4.1 Strike to power line
          A.4.2 Strike to the telecommunication cable
          A.4.3 Strike to the structure
     I.1 Introduction
     I.2 Resistance to earth at the strike point
     I.3 Equivalent circuit of a strike to earth
     I.4 Simulation results for a 30 pair 0.64 mm MB cable with a zero ohm resistance to earth at the customer end
     I.5 Simulation results for a 30 pair 0.4 mm non-shielded cable
     I.6 Conclusions drawn from the simulations
     I.7 Calculation of cable current
     I.8 Determination of the cable surge generator.