EN 50423-1-2005 pdf download.Overhead electrical lines exceeding AC I kV up to and including AC 45 kV Part 1: General requirements —Common specifications.
With respect to the calculation and construction of supports, overhead lines with nominal voltages exceeding AC 1 kV up to and including AC 45 kV shall be generally designed according to EN 50341-1 and the associated NNAs. The following clauses specify additional requirements and simplifications that apply only for these voltage ranges. In respect of the Empirical design approach, established mechanical design bases may be separately specified in the NNAs.
7.1.1 Structural design resistance of a pole
Structural design resistance (R,) of a pole (see Subclause 3.7.3 of EN 50341-1) due to bending is the overall load applied horizontally to the top of the pole as detailed by the pole supplier for a given foundation depth, with any vertical load ignored.
7.1.2 Buckling Resistance
For self-supporting structures where vertical loads are high andl or soil conditions are poor arid/ or a high slenderness ratio is apparent, the buckling resistance of the structure shall be considered.
7.2.6 Timber
Timber poles shall be specified in conformity with the requirements of EN 14229, EN 12465, EN 12479, EN 12509, EN 12510 and EN 12511.
7.5 TImber poles
In addition to the requirements specified in EN 50341-1 a variety of different dimensioning variants exist in Europe that have all been proven in practice. If necessary, the requirements shall be dealt with in the NNAs.
7.5.1 General
The requirements of ENV 1995-1-1 shall be complied with, except where otherwise specified in EN 14229, EN 12465, EN 12479, EN 12509, EN 12510 and EN 12511. Industry experience Indicates that modification factor noted in Table 3.1.7 of ENV 1995-1-1 shall be 1,0 for all solid wood pole supports. K factors for glu-lam wooden pole supports shall follow the requirements included in
ENV 1995-1-1.
7.6 Concrete poles
The dimensioning and construction shall be in accordance with EN 12843 (in preparation).
7.7 Guyed structures
All guys for timber poles and poles of materials with insulating properties shall be equipped with a sufficiently designed insulator such that the distance between the lower part ol the insulator and ground shall be at least 3,0 m (for both mechanical and electrical reasons) (see HO 637 Si) unless the guy is electrically bonded to earth at the ground end or structure end.
7.10.1 Climbing
The design of structures shall take Into account the requirements of safe climbing procedures. Each NC shall record in the NNAs the safe method of access to the pole support.
8 Foundations
The provisions in EN 50341-1 apply. Detailed specifications and additional requirements to these shall be specified in the NNAs or project specification.
8.5 Geotechnical design
8.5.1 General
Overhead lines with nominal voltage exceeding AC 1 kV up to and including AC 45 kV. using timber poles as supports, shall normally use foundations designed in accordance with Subclause 8.5.3. Good quality backfill or concrete may be required in poor soils.
8.6 Loading tests
Loading tests on pole foundations are only required where an unsatisfactory service history is evident.
9 Conductors and overhead earthwires (ground wires) with or without
telecommunication circuits
9.1 Introduction
With respect to the dimensioning of conductors and overhead earthwires (ground wires), bare overhead lines with nominal voltage exceeding AC 1 kV up to and including AC 45 kV shall be designed according to EN 50341-1 and the associated NNAs. Lines strung with covered conductors (in accordance with EN 50397-1) and overhead, insulated cable systems with nominal voltage exceeding AC 1 kV up to and including AC 45 kV shall be designed according to this standard. The following clauses specify additional requirements and simplifications that apply only for these voltage ranges.
9.6 General requirements
9.6.3 Minimum cmss-sections
Due to the risk of fatigue failure, it is recommended that solid single wire conductors, or conductors having a cross-sectional area of 25 mm2 or less, should not be used unless a satisfactory service performance history indicates that such conductor sizes are suitable.EN 50423-1-2005 pdf download.