Note: Descriptions are shown in the official language in which they were submitted.
1 The invention relates to a compound cable comprising
an aluminum cable, an aluminum alloy cable~ an aluminum
cable steel reinforced or aluminum alloy cable steel re-
inforced with reduced audible noise for use in a high voltage
transmission line.
~ he aluminum cable~ alumi~um alloy cable t aluminum cable
steel reinforced or aluminum alloy cable steel reinforced
(hereinafter referred to as a compound cable) conventionally
used in the overhead transmission line has played an important
role in power transmission. In recent years -the transmission
voltage has come to be elevated due to the necessity of
large capacity transmission. However, when the voltage is
as high a3, for example, lO00 EV9 the corona discharge,
particularly the audible noise directly after rainfall9 poses
a problem.
~ he audible noise directly after rainfall is caused by
the corona discharge produced by the elevated surface potential
gradient around the rainarop projecting beyond the surface
of the compound cable. The invention ha~ succeeded in pre-
venting the generation of the corona discharge by increasing
the wetness (hydrophilic property) a well as the draining
property of the surface of the compound cable thereby
enabllng to cause the raindrops to disappear quickly from
said surface,
~he hydrophilic property can be imparted to the aluminum
~urfaGe byv~rious methods. ~owe~er, the anodic oxidization
treatment has a disad~antage in that lt is necessary to
remo~e a rigid insulating film formed on ~he surfaceO
q~
s~ l
1 The invention has been made as a result of a series of
tes-ts for the elimination of the said disadvantage~ ~he
inventio.n is firstly characterized in that it can provide
a compound cable with reduced audible noise by forming a
specific surface treatment film on the surface of the
aluminum wires or aluminum alloy wires (hereinafterrefe~red
to as aluminum wires) to con~titute the outermost layer
of the cable thereby enablïng ~o im~ro~e the hydrophilic
property of the surface of said cable.
The invention is secondly characterized in that (1~
more than 30~ of the aluminum element wires to constitute
at least the outermost layer of the cable are provided on
the outer peripher~es thereof with more than 3 grooves
formed continuou~ly and longitudinally of said wires
respectively~ that (2) a specific surface treatmerlt film
is provided on the surface including the grooves o~ each
o~i the element wires, and that (3) said specific surface
treatment ~ilm i~ provided af.ter subjecting the surface
o~ theelement wire to rough surface treatment; thereby
enabling to provide a compound cable with reduced audible
noise.
In fine, the invention is characterized in that the
surface of a compound cable comprising aluminurn wires
~tranded around the outer per~phery of a steel core is
subjected to a treatment in the water or aqueous vapor at
a temperature of 90C and upward or in aqueous vapor having
a temperature abo~e 120~ and a pressure above 2 kg/cm2
~o ~s to produce a hydrated film thereon thereby enabling
the surface of the cable to have a hydrophilic-property~
1 The invention i8 further characterized in that more
than 3 groovas are formed on the outer peripheries of more
than 3O% of the aluminum wires to constitute at least the
outermost layer of the cable continuously and longitudinally
of said aluminum wires9 respectivelyO
The outlIn~ of the accompanying drawings in the present
invention i9 a~ follows:
Figs. 1 and 2 are cross-sectional views showing
embodiments of the compound cable according to the inYention
in which aluminum wires having hydrated films on the surfaces
thereof respectiYely are used in the outermost layer of said
cable.
Fig. 3 is a cross sectional view of ~n aluminum wire
formed with grooves longitudinally thereof according to the
invention~ -
Fig. 4(A) to (D~ show cross-sectional views illustrat~
ing further embodiments of the grooves formed on the
aluminum wires in different numbers and configurations,
re~pectively.
A compound cable of the present invention will be
described on an aluminum cable steel reinforced ~ACSR)
as one of the most typiG~, compound cables as follows:
In Fig~ 1, around a steel reinforcement there are
stranded an inner layer comprising aluminum wires 2 and
then an outermost layer comprising aluminum wire~ 3 wnth
surface treatment films formed on the surfaces thereof.
In Figo 2~ aluminum wire~ 2, 13 are stranded around a
~, /~ s
steel reinforcement 1, surface treatment-fil~m 14 being
formed on t~e outermost surfac~s of the aluminum wires 13
1 constituting the outermost layer~
According to the in~ention~ the surface treatment film
is formed on the surface of each of the aluminum wires to
cons~itute the outermost surface of the cable either by
treating the surface of the compound cabls or by treating
the surfaces in the ~tate of element wires prior to stranding
of said element wires into a compound ~able. In both cases~
it is essential that the wP~e drawing lubricant is completely
removed by an organic solvent before the film is formed on
the surface.
In order to obtain a greater effect, it i5 preferable
that the surface of the aluminum wire is subjected to a
rough surface treatment~ such as blasting, liquid horning,
etc.~ after the oil removing process by means of the organic
solvent. According to the invention, the blast treatment
comprises the ordinary sand blasting and shot blasting.
~he roughness of the surface treated by blasting or liquid
horning i9 preferably about 10-50~since it has an advantage
in that not only the hydrophilic property i~ satisfactory
after the formation of the hydrated film but also mass
production is feasible from the industrial viewpointO
When tha surface of the ACSR is simply subjected to the
blast treatment or liquid horning treatment, the beads of
raindrops adhering to the surface ha~e the same effect as
the aforesaid projections thereofO It is impossible, there-
~ore~ to reduce the audible noiseO ~nhen h~drated film is
ormed on the sur~ace in the water or aqueous ~apor of 90C
and upward after it has been subjected to blast treatment
or liquid horning treatment~ the surface has an improved
1 hydrophilic prope~tyO Thus the raindrops are uniformly
dispersed over the surface without forming beads thereby
enabling to greatly reduce the corona discharg0 and aceording-
ly the audible noiseO Generally9 when a body is bro~ght
into contact with water7 the relation between the contact
angle ~ in case of a plane faced body and the contact angle
~' in case of a rough~faced body is as followsO
C08 ~ true sur~aee area
_ _ = r
cos 9 apparent surfaoe area
In case o~ a rough face, the true surface are is larger than
the apparent surface area. Since r~l, in case of OD< ~<~D~
~ . Thus the apparent contact angle becomes ~maller9
whereby the hydrophilic property of the rough face is improved~
However, a simple treatment of blasting or liquid
horning is not sufficient to prevent the rain~rops from
forming projections on the surfaceO Since the corona dis-
charge is sub~t~ially.;same as in the case of the ordinary
~CSR, there is no improvement in the reduction of the audible
noise. ~hus it has been found that the hydrophilic property
is never impro~ed by simply roughening the surface~ When
the hydrated film is caused to form ~h the water or aqueou~
vapor of 90 C and upward after the sur~ace has been sujected
to blast treatment or liquid horning treatment~ the film
is produced in grea~er amounts under the Sam8 conditions
since the sur~ace area has been increased due to the roughen-
ing process compared with that of the ordinary ACSR. In
addition, -~he surface roughness of about 10-50~ after the
blast treatment or liquid horning treatment is substantially
doubled to about 20-lOOJ~ . Thus it has been ~ound that
-- 5 --
1 the hydrophilic property of the surface of the cable is
remarkably increased by the mul-tiplied effect of the improved
hydrophilic property due to the hydratea film combined with
the further roughening of the surface.
According to the invention, the hydrated film is cau~ed
to form ~nthe water or aqueous ~apor of 90C and upward so
that the surface may ha~e higher hydrophilic property and the
surface roughness may substantially be -twice as large as
that after the blast or liquid horn~ treatment thereby
enabling to drastically improve the hydrophilic property
of the surface of the cable~ When treated in aqueous vapor,
the hydrophilic property is further increased compared with
the ~ase of the water treatment in the same perlod of time.
If the temperature of the water or aqueous vapor is
lower than 90C, the hydrophilic property of the surface
is not improved satisfactorily~ In case of the aqueous
vapor~ if the surface is treated in aqueous vapor of a high
temperature above 120C having a pressure of 2 kg/cm2and
I upward, the hydrated film can be formed in a shorter period
of time co~pared with the case of the ordinary atmospheric
pressure. ~he film has higher crystallizing property and
stability compared with the film produced at a low temperature.
A surface treatment ~ilm of higher hydrophilic property is
obtainable in the same period of time of treatment. To be
nore precise~ -the invention has an industrial advantage in
that a predetermined hydrophilic property is obtainable
in a shorter period of processing time~
When the aqueous vapor has a pressure less than 2
kg/cm2 and a temperature below 120C~ it is impossible to
- 6 =
l obtain a surface treatment film of high hydrophilic property
and stability. In practice9 however~ either the pressure
or the temperature can be conformed to the said conditions7
since there is a correlation between the pressure and the
temperature of the aqueous vapor~ The surface treatment
film under the said conditions has a thickness below 10% of
that of the anodized film. Thus the film according to the
invention is readily broken when the wires are connected by
means of a comprssion type sleeve thereby enabling an electric
contact to be formed between the ACSR and the sleeve. The
invention, therefore9 has an advantage in that there is no
necessity for removing the filmO
The invention will now be described in detail in
relation to the second characteristic thereof: more than 3
grooves formed on the outer periphery of each of the aluminum
wires of the ou-termost layer continuously and longitudinally
thereof.
When more than 3 grooves are formed on the outer
periphery of an ~luminum element wire continuously and
longitudinally of said wire, the number, size and configu-
ration of the grooves ha~e a great influence not only on
the formation of waterdrops but also on -the tensile
strength and vibration fatigue resistance of the element
wire and accordingly the ACSR.
According to the invention, on the outer periphery of
each of the aluminum element wires to constitute at least
the outermost layer of the ACSRg there are formed more than
3 grooves continuously and longitudinal~y of said element
wire for the following reasons~ In order ~o reduce the
t~
1 audible noise~ it is necessary that the hemispherical
waterdrops formed on the outer surface of the AC~R are
caused to disappear. If more than 3 grooves are formed
on the surface of each of the element wires to constituts
- the outermost layer of the ACSR for the said object, at least
one groove appears on the surface of each of the element
wires constituting the outermost layer of -the ~CSR exposed
to the atmosphere~ raindrops being entrapped into the
grooves due to the geometric onfiguration thereof. Thus
the hemispherical raindrops on the surface are reduced in
number7 while water flows along the grooves7 thereby
enabling to greatly increase the draining proper-ty of the
surface of the cable~
The grooves are provided on at least more than 30~O of
the element wires constituting the outermost layer of the
cable inasmuch as, if less than that, no satisfactory effect
can be expected.
~ le opening of the groove should ha-ve a width of O l-
2 mm, since if wider than 2 mm~ the draining property is
impaired and accordingly the effect of reducing -the audible
noise is reduced9 the same being applicable to the case of
less than 0.1 mm. The depth of the groove should be 2-25~o
of the thickness of the element wire since if below 2 %7
the groove is imperfect in its configuration7 while if
deeper than 25~ the vibration fatigue resistance is reduced
thereby posing a problem in respect of practical use.
~igs9 3 and 4 show element wires S having grooves of
U-shaped profiles and arcuate profiles~ respectivelyO
Though the groove may have a V-shaped profile~ U-shaped
-- 8
1 profile is preferable because of its smaller stress concen-
tration~
A hydrated film is formed on ~e outer surface of the
aluminum wire including the grooves formed thereon in
aqueous vapor having a temperature of 120C and upward; and
preferably in the water or aqueous vapor above 90C after
the outer surface has been subjected to rough surface
treatment.
The aqueous vapor treatment should be effected at a
temperatw e above 120C inasmuch as the film can be formed in
a shorter period of time~ Moreover, the film thus obtained
has higher crystallizing property and stability compared
with the film obtained at a lower temperature, thereby
enabling to improve the hydrophilic property and draining
property and accordingly to reduce the audible noise9
The hydrated film is provided on the surface including
the grooves of each of the element wires to constitute
the outermost layer of the cable. Alternatively~ said film
may be provided on the outer surfaces of the grooved
element wires constituting the outermost layer of -the cable
after it has been strandedO The effect is identlcal in
both cases a
According to the invention, more than 3 grooves are
formed on the periphery of each of the element wires
corresponding to 30~ and upward of the element wires
constituting the outermost layer of thecable thereby enabling
to reduce the audible noise in conformity with the object
of the inventionO It is also within the scop~ of the
i.nvention -to provide more than 3 grooves not only on the
_ 9,
1 elemenk wires of the outermost layer but also on all the
aluminum wires with e~ception of the core wires thereby
enabling to reduce the weight of the compound cable, for
example, ACSR~
According to the invention, the reinforce~ent in the
center of the cable comprises all kinds of steel wires,
aluminum wires and the like used singly or in plurality~
A compound cable the outermost surface of which is
composed of a surface treatment film as described herein-
before, or a compound cable in which more than 3 grooves
are formed on each outer periphery of more than 30% of
the element wires to constitute the outermost layer
continuously and longitudinally of said wires, or a
compound cable on which a hydrated film is formed or a
hydrated film is formed after rough surface treatment has
an advantage in that not only its hydrophilic property
but also its draining property is improved thereby
enabling to reduce the audible noise in a short period of
time directly after rainfall.
Although the aluminum cable steel reinforced as one
of the compound cables has been described in detail, it
is to be understood that the present invention is not
limited to ACSR only, but that a core wire composed of
steel wire or aluminum wire and a cable in combination
with a steel wire or aluminum wire may be used. In the
present invention~ it is necessary that at least the
outermost layer of the cable is composed of a compound
cable consisting of an aluminum wire, aluminum alloy wire,
aluminum-clad steel wire or aluminum-alloy-clad steel wire~
--10--
1 ~he invention will hereinunder be described in detail
in reference to the following examples~
Example 1
Heat resisting aluminum alloy wires were stranded into
ACSR (60T ACSR) having a sectional ar~a of810 mm2 and a
conductivity of 60~o~ the surface thereof being subjec-ted
to continuous sand blast treatment until the surface rough-
ness of the aluminum alloy wires of the surface of the ACSR
was on the order of 15~.
~he cable thus obtained was su~jected to oil removing
treatment by an organlc solvent, hydrated films being caused
to form under different conditions as shown in Table 1, to
produce ACSR samples according to the invention.
By way of comparison7 thera were prod~ced an ordinary
new 60~ ACSR (No. 13)7 60T ACSR subjected to sand blast
treatment only (Nol 12), and 60T ACSR treated under ~he
conditions of No.14 and No~15 of Table 1 after sand blast
treatment~
An audible noise test was made on said ACSR samples,
the results being as shown in ~able 1. The audible noise
test was mada by comparing the audible noises at a maximum
surface potential gradient of 15~5 KV/cm after flooding for
1 minute at an intensity of 1~6 mm/hr on the hypothesis of
directly after rainfall. The noise levels (dB, A character-
istic~ in Table 1 show the values of measurement in the
lapse of 5 minutes after flooding~
1 Table
. _ '~reatment Treatment Noise Level
No. Temperature Time ~dB, A characteristic)
(C) (m~n)
1 - 95 5 49
2 ~ 95 10 47
3 ~ 95 20 46
~ 4 .~ 95 3o 46
H 5 _ 95 50 46
~ 6 ~ 100 15 ~7
~ 7 g 100 3o 46
120 10 46
9 o 120 20 46
1~ ~ 140 10 43
.~ 140 20 ~4
12 h 54
13 ~ . . 57
~ ~ 14 ~ 1 70 3o 53
o ~ 15 1 70 5 52
As is clear from Table 1, the ACSR samples according
to the invention show lower noise levels by as much as
8-14 dB compared with the ordinary ACSR sample (No.13).
With the comparative sample subjected to sand blast treat-
ment only (No.12) and those treated in the water of a low
temperature (NoO14 and No.15), the reduction of the noise
levels is very small.
Example 2
An ACSR (6GT ACSR) having a sectional area of 810 mm2
and a conductivity of 60% was produced by use of heat
resisting aluminum alloy wires. The ACSR was de-greased
by use of an organic sol~ent~ surface treatment film being
- 12 -
~ 5 ~ ~ I
1 caused to form by the batch system under different
conditions as shown in ~able 2, to obtain ACSR samples
according to the invention~ Since there is a correlation
between the pressure and temperature of the aqueous vapor~
the condi-tions hereinafter will be designated by the
pressure onlyO By way of comparison, there were p~oduced
a sample of ordinary new 60T ACSR in the state in which
oil had been removed (NoO8) and 60T ACSR samples with the
surfaces thereof being treated under the conditions of
No.9 and NoO10 of Table 20
The results of an audible noise test made on said
ACSR samples were ~s shown in Table 2.
The audible noi~e test was made by comparing the
audible noises after flooding at an intensity of 1~6 mm/hr
for 1 minute and a maximum surface potential gradient of
15~5 KV/cm on the hypothesis of directly after rainfall.
The noise levels (dB~ A characteristic) in Table 2 shows -
the values of measurement in the lapse of 5 minutes after
the suspension of flooding.
As is apparent from Table 2, all the ACSR samples
according to the invention have lower noise levels by as
much as 4-9 dB compared with the noise level of the
comparative sample No.8, while the comparative samples,
No.9 and No.107 show poor results, the noise level being
still high even in the case of No~10 treated for 60 minutes~
- 13 -
1 ~able 2
_ .
Aqueous Treatment Noise ~evel
NoO Vapor 2 Time (min~ (dB 9 A haracter
Pressure (Kg/cm ) istic)
=~ __ ~_~ .
1 2~5 5 50
2 2~5 15 47
3 2.5 30 47
4 2.5 50 46
~0 10 46
~ 6 3O0 30 46
~ 7 3~0 50 45
8 . - _ ~ 54 .
~.~ 9 1.0 30 52
E ~10 1 . O 6 ~ . `
Example 3
Hard-drawn aluminum wires of 4.8 mm~ were subjected to
continuous oil removing treatment and then to aqueous
vapor treatment under different conditions as shown in
Table 3.
The wire thus treated were stranded as element wires
GO constitute the outermost layer of ACSR having a sectional
area of 810 mm20 Since the wires had no oil on their
surfaces, a lubricant was applied thereto prior to strand-
ing so as to pre~ent the parts brought into contact with
guide rolls and the like from receiving damage7 said
lubricant being removed after stranding~
The samples thus obtained were subjected to the same
audible noise test as in Example 1. The results were as
shown in ~able 3O
- 14
1 ~able 3
, .
Aqueous Treatment ¦ Noise ~evel
No G Vapor Time ~min) ¦ (dB, A Characteristio)
Pressu~e
(Kg/cm )
__, . . _ _
1 3O5 5 47
2 3O5 15 46
3 3O5 30 45
4Oo 1 47
~.0 5 46
6 4~0 10 45
lo 7 4O5 0~5 47
8 4O5 3 46
9 445 5 45
~ , . _ _ _~___ .
As is apparen-t from Table 3, all the ACSR samples
according to the invention show highly satisfactory results9
the noise levels being reduced by as much as 7-9 dB
compared with the case of the comparative sample No~ 8 of
Table 2.
Example 4
U-shaped grooves of different depth3 as shown in
Fig. 3 were provided on the peripheries of heat resisting
aluminum alloy element wires 4.8 mm~in outside diameter~
The vibration fatigue resistance of said element
wires was examined to obtain the results as shown in
Table 4O
The op~ning of the groove had a width of 1-1.5 mm.
- 15 -
1 ~able 4
~ ~.
Depth of Groove Vibration Fatigue
(% relative tc diameter of Resistance (kg~mm2)
element wire) at 10' Times
0 5q5
5~
5~5
5~5
4~0
It ha~ been found from Table 4 that, when the depth
of the groove is as mucha~ 30% of the diameter of the
element wire, the vibration fatigue resistance of the wire
is decreased thereby reducing the utility of said wire for
use in a cable.
Example 5
Samples of ACSR of the same construction as that of
810 mm2 ACSR were produced by use of aluminum element wires
408 mm~ in outside diameter for the outer layer of the
cable with 4 grooves formed continuously and longitudinally
of said wires respectively, each of said grooves having
a U~shaped profile as shown in Fig. 3 with its opsning
having a width of 1 mm and its depth extending to 20~o of
the diameter of ~aid wire.
~he ~CSR samples thus produced were subjected to
different surface treatments as sho~ in Table 5 and then
to an audible noise test.
The audible noise test was made under the conditions
of maximum surface potential gradient 14.0 KV/cm after
~looding for 1 minute at an intensity of lo 6mm/hr on the
- 16 -
hypo thesis o f dire c tly after rain f all 4
By way of comparison, the same test was made on an
ordinary 810 mm2 ACSR (No.10). Table 5 shows the results
of the test.
- The rough surface treatment was effected by sand
blast treatment.
-- 17 --
'J~~ $~ `
1 ~able 5
~,. ,, __ ~
Rough ~ydrated Film Audible Noise
No~ Surface ~reatment I ~est
Treat- Treatment Treatment ~Audible noise
ment ~emperature(C) Time (min) level in
lapse of 3
minutes after
suspension -
of flooding3
Character-
i~tic)
_ . . _ _ ___
1 _ _ _ 49
2without in aqueous 20 46
3pOoOrc
3 - 130C 50 44
.i 140C 30 42
~ 5 with 100C 10 44
H 6 ll .,
: ~ 7 ll 120C 10 40
140C 10 39
8 ll in wa~er
95 C 30 46
9 . ~1
95C 60 ~5
. _ __ , _ _
~ 10 _ _ _ 53
~ ~ _ _ , _ - . ~_ -.
It ha~ been found from ~able 5 that the ACSR s~mples
according to the invention have a high effect in reducing
the audible noise lsvels by as much as 4-14 dB compared with
the ca~e of the conventional ACSR.
- 18 -
