IEC 62420 pdf – Concentric lay stranded overhead electrical conductors containing one or more gap(s)

IEC 62420 pdf – Concentric lay stranded overhead electrical conductors containing one or more gap(s)
1 scope
This International Standard specifies the electrical and mechanical characteristics ofconcentric lay stranded overhead electrical conductors，containing one or more self-supporting aluminium or aluminium alloy layer(s) as depicted in Figure 1, made ofcombinations of any of the following metal wires:
a) hard-drawn aluminium as per lEC 60889, designated A1;
b) aluminium alloy type A or B as per IEC 60104, designated A2 or A3;
c) thermal resistant aluminium alloy type as per lEC 62004,designated AT1，AT2，AT3 orAT4;
d) regular strength steel as per lEC 60888, designated S1A or S1B;e) high strength steel as per lEC 60888, designated S2A or S2B;f)extra-high strength steel as per lEC60888, designated S3A;
g) aluminium-clad steel as per lEC 61232, designated 20SA,27SA,30SA or 40SA.
NOTEThis standard covers the construction of self-damping conductors， as well as gap-type conductors.Although both types of conductors share a common design feature and the presence of one or more gaps betweenlayers, they are intended for different purposes. Self-damping conductors (SDC) may have more than one gap toprovide increased self-damping, whereas gap-type conductors are so designed as to allow the aluminium layers toslide freely over the core during installation, and therefore usually do not require more than one gap.
The various metal combinations permitted by this standard shall be in accordance withTable 1.
2Normative references
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies.For undated references, the latest editionof the referenced document (including any amendments) applies.
IEC 60104:1987,Aluminium-magnesium-silicon alloy wire for overhead line conductorslEC 60888:1987,Zinc-coated steel wires for stranded conductors
IEC 60889:1987,Hard-drawn aluminium wire for overhead line conductors
IEC 61232:1993,Aluminium-clad steel wires for electrical purposes
IEC 61395:1998,Creep test procedures for stranded conductors
lEC 62004:2007,Thermal resistant aluminium alloy wire for overhead line conductors
3Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aluminium
all types of aluminium and aluminium alloys listed in Clause 1
3.2
annular gap
constant space，void of any material except for air or grease,between two layers of aconductor
3.3
canting
phenomena by which a formed wire is twisted relative to its own axis，thus producing aprotuberance outside the layer
3.4
conductor
material intended to be used for carrying electric current consisting of a plurality ofuninsulated wires fwisted together
3.5
concentric lay stranded conductor
conductor composed of a central core surrounded by one or more adjacent layers of wiresbeing laid helically in opposite directions
3.6
direction of lay
direction of twist of a layer of wires as it moves away from the viewer , with a right-hand laybeing a clockwise direction and a left-hand lay being an anti-clockwise direction
3.7
equivalent wire diameter
the diameter of a round wire which would have the same cross-sectional area as a givenformed wire
3.8
formed wire
filament of drawn or rolled metal having a constant。non-circular cross-section
3.9
layer
group of wires located at a constant radial distance from the centre of the conductor
3.10
lay length
axial length of one complete turn of the helix formed by an individual wire in a strandedconductor
3.11
lay ratio
ratio of the lay length to the external diameter of the corresponding layer of wires in thestranded conductor
3.12
lot
group of conductors manufactured by the same manufacturer under similar conditions ofproduction
NOTE A lot may consist of part or all of the purchased quantity .