IEC 61774 : 1.0

OVERHEAD LINES - METEOROLOGICAL DATA FOR ASSESSING CLIMATIC LOADS

International Electrotechnical Committee

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FOREWORD 1 Scope 2 Normative reference 3 General     3.1 Meteorological data     3.2 Ice loads           3.2.1 Icing processes           3.2.2 Icing measurements           3.2.3 Icing models     3.3 Galloping (informative)     3.4 Strategy for employing data and models 4 General meteorological data     4.1 Introduction     4.2 Weather parameters as required by IEC 60826           4.2.1 General           4.2.2 Wind and thermal loads           4.2.3 Weather elements required by icing models     4.3 Availability of meteorological data for           overhead line conductors     4.4 Recommended procedures 5 Ice load measurements     5.1 Introduction     5.2 Standard methods and recommended options for ice           load measurements associated with overhead           line conductors           5.2.1 General           5.2.2 Consideration for ice load measurements           5.2.3 Minimum recommendations           5.2.4 Rods for additional investigations           5.2.5 Characteristics of sites           5.2.6 Standard procedures for measuring ice                   load on simple rods           5.2.7 Training of observers     5.3 Test spans     5.4 Recommended procedures 6 Icing models     6.1 Introduction     6.2 Types of icing models           6.2.1 Empirical and deterministic icing models           6.2.2 Climatological data used in icing                   models           6.2.3 Application of icing models Figure 1 Strategy flow chart Table 1 Ice measurement parameters Annex (informatives) A Overview of weather parameters required by IEC 60826 B Overview of meteorological terms, data handling     programs and forecasting models     B.1 Weather elements and weather parameters     B.2 General observation procedures     B.3 Meteorological forecasting models C Examples of construction of ice load measuring rods     and applicability to various types of icing     C.1 Glaze caused by freezing rain     C.2 In-cloud icing including hard rime and soft           rime     C.3 Wet snow accretion     C.4 Dry snow accretion D Examples of test spans E Examples of icing models     E.1 Glaze ice     E.2 Rime ice     E.3 Wet snow     E.4 Glaze ice, rime ice and wet snow     E.5 Rime ice and wet snow F Evaluation of icing models     F.1 Introduction     F.2 Glaze ice     F.3 Rime ice     F.4 Wet snow     F.5 Relevance of local weather data     F.6 Availability of information on icing models G Basic icing model concepts H Bibliography J Bibliography for further reading