Note: Descriptions are shown in the official language in which they were submitted.
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TITLK OF THE INVKNTION
HEAT-GENERATIVE ELECTRIC WIRE
BACKGROUND O~ THE INVENTION
This invention relates to a heat-generative ele¢tric
wire oapable of preventing adherence of snow or ioe to
overhead eleotri¢ wires.
When snow or ioe is attaohed to the overhead
eleotrio wire, the snow or ioe grow~ while rotating along
the stranded groove of the overhead electric wire, and
finally develops into an extremely large ¢ylindri¢al-form
of snow or extremely large lump of ioe. A~ a result, the
load applied to the overhead eleotri¢ wire in¢reases,
thereby ¢au ing wire ao¢idents su¢h as breakage of the
overhead eleotri¢ wire and fall of a pylon. ;
In view of the above faot, a method is pra¢tioally
us~ed in whioh a~plurality of snow-adheren¢e ~uppression
rings are disposed at a regular interval in the
longitudinal direotion of the periphery of the overhead
eleotrio wire to prevent attaohed snow or i¢e from being
rotated along the~stranded ~ro*ve and drop the attaohed
snow or the like before lt beoomes lar~e. However,
aooording to this method, there ooour~ a problem that
vi~nyl plastio hothou~es, oars or the like lying direotly
below the overheat ele¢tri¢ wire will be damaged by ~all
of snow or ioe.
Therefore, various methods have been proposed to
olve the sbove problem. For example, there is proposed
a method o~ meltin~ snow or ioe on the ele¢trio wire by
windin~ magnetio sub~tanoe on the overhead eleotrio wire
and oausing the ma~netio substanoe to generate heat by
eddy ourrent 1088 oaused by an eleotrio field of a
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current which flows in the overhead eleotrio wire
(Japanese Patent Disclosure No. 58-44609). Fe- and Ni-
alloys ~uch aa Fe-Ni, Fe-Ni-Cr, Ni-Al, Ni-Si and Ni-Cr
are uaed a~ preferable material for the above magnetic
aub~tance.
The amount of heat generated by the above magnetic
alloy significantly varies according to the amount of
electric power transmitted by mean~ of the overhead
electric wire. Generally, the heat generation becomes
small when the amount of transmission power is small, and
it tends to increase a~ the amount of transmission power
becomes larger.
However, adherenoe of snow or ice to the overhead
electric wire seldom occurs in the daytime during which
the amount of transmisYion power is large and heat is
generated by means of re~i~tance of the overhead electrio
wire itself due to the large amount of transmission
power, but it tends to ocour in a period of time from the
night to the morning during whioh the amount of
transmi~sion power is small and the temperature becomea
low. Therefore, with the conventional magnetio alloy,
the amount of generation heat is small when the amount of
transmission power is small and a suffioiently large
effeot of melting snow or the like oannot be attained.
Further, the oonventional overhead eleotrio wire
using the above magnetio alloy is exoessively heated in
the daytime by heat generation due to the resistanoe of
the overhead electrio wire itself and heat generation in
the magnetio alloy 80 that the temperature of the
overhead eleotrio wire may be exoessively raised. As a
result, there ooours a problem that the amount of
transmission power in the overhead eleotric wire must be
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restricted.
Further, eleotrolytic corrosion may occur and rust
may oocur in the overhead electric wire depending on the
composition of the magnetic alloy wound on the overhead
electric wire, thereby reducing the efPeotive diameter.
SUMMARY OF TH~ INV~NTION
An object of this invention i8: to provide a heat-
generative electrio wire whioh oan generate a
suffioiently large amount of heat even in the case of
small electric power transmission amount to melt snow or
ioe attaohed thereto 80 as to prevent formation of a
oylindrioal-form of snow or lump of ice, and whioh will
not be exoessively heated in a case where a large amount
of eleotrlo power is transmitted.
Another objeot of this invention i~ to provide a
heat-generative eleotric wire in whioh influence by
eleotrolytic oorrosion of an overhead eleotrio wire due
to magnetio alloy is suppressed.
`~ A still another objeot of this invention is to
provide a heat-8enerative eleotrio wire on whioh magnetio
alloy oan be easily wound.
The inventors of this lnvention devoted them~elves
to researoh in view of the above faot and found that Ni-
Fe series alloy is a suitable material a~ the ma~netio
alloy. They have made further experiments and re~earohes
to find that the Ni-Fe series alloy may have different
heat ~eneration oharaoteristios depending on the amount
~; of Ni oontained therein in oa~es where the power
transmission amount is small and large, and thus
completed this invention.
That is, this invention is a heat-generative
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electric wire which has a feature that a Ni-Fe series
alloy wire member containing Ni of 45 to 80 X by weight
and the remaining portion of Fe is wound on or stranded
with the outermost layer of the overhead electrio wire.
In the specification of thi~ invention, the Ni-Fe series
alloy wire member inoludes a Ni-Fe series alloy wire
member oontaining a small amount of Mn, Cr, Al or the
like in addition to Fe as the remaining portion.
Preferably, the Ni-Fe series alloy wire member has a
metal ooating formed on the surfaoe thereof.
The aforementioned and other objeots, features and
advantages of the present invention will become more
apparent from the following detailed desoription based on
the aooompanying drawings.
BRIFP DRSCaIPTION 0~ THK DPAWINGS
Fig. 1 is a side view showing a heat-generative
eleotrio wire of this invention;
Fig. 2 is a oirouit diagram of an energization
oirouit u~ed for energization test for the heat-
generative eleotrio wire having a Ni-Fe series alloy wire
member wound of Fig. 1;
Fig. 3 is a heat generation oharaoteristio diagram
in a oase where the values o~ ener~ising ourrent in Ni-Fe
series alloy wire member~ oontainin~ different amounts of
Ni are ohanged;
Fig. 4 i8 a side view of a heat-generative eleotrio
wire having a Ni-Fe series alloy wire member wound in a
direotion different from that in the heat-generative
eleotrio wire shown in Fig. I;
Fig. 5 is a cross seotional view of a heat-
generative eleotrio wire having Ni-Fe series alloy wire
members stranded with strands on the outermost layer
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2013792
constituting a overhead electric wire;
Fig. 6 is a heat generation charaoterlstic diagram
of a Ni-Fe series alloy wire member in a heat-generative
electric wire in a case where a Zn coating i8 formed on
the~Ni-Fe series alloy wire member wound on the overhead
electric wire and in a case where the Zn coating is not
formed;
Fig. 7 is a side view showing a heat-generative
electric wire having a Ni~-Fe series alloy wire member
pre-formed in a spiral form and mounted thereon;
Fie. 8 is a heat eeneration oharaoteristio ourve
diaeram dependine on the differen¢e in the pitoh of the
Ni-Fe series alloy wire member mounted in the heat-
generative electric wire of Fig. 7; ~ ~
Fie. 9 is a side view of a Ni-Fe series alloy wire
member pre-formed of three wires integrally formed in a
spiral confieuration;
Fie. 10 is a side oross sectional view showing the
state in which a protection member is mounted on the end
portion of a Ni-Fe series alloy member~wound on the -
overhead electric wire; and
Fie. 11 is a oross seotional view taken alon~ the
line XI-XI of Fig. 10.
D~TAILRD D~8CRIPTION
In this invention, a Ni-Fe series alloy wire member
whioh is wound on or stranded with the outermost layer of
a overhead eleotrio wire eenerates a signifioantly
inoreased amount of heat when the power transmission
amount is laree in a case where the amount of Ni
contained therein is less than 45 % by weight (which is
~ heFeinafter simply expressed by X). It generates a less
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amount of heat when the power transmission amount is
small in a case where the amount of Ni is more than 80 X,
thereby preventing a sufficiently effective snow or ice
melting effect from being attained. The content of Ni is
more preferably 47 to S4 %, and most preferably, 50 to 52
Since the Ni-Fe series alloy wire member has a large
relative magnetic permeability, it generates a sufficient
amount of heat for melting snow or ice even in a case
where the power transmis~ion amount along the overhead
eleotrio wire is small. Further, sinoe the Ni-Fe ~eries
alloy wire member may reaoh a magnetio saturation in
whioh the magnetic flux density B of the magnetio metal
wire member is saturated, by weak magnetio field H, the
heat generation amount thereof is small even if the power
transmission amount beoome~ large. Thus making it
unneoessary to limit the power transmission amount for
suppressing temperature rise in the overhead electric
wire. Therefore, the heat-generative electric wire of
this invention may provide a suffioiently large snow or
ice melting ef~eot even in a period of time from the
midnight to the early mornin~ durin~ which the power
transmission amount beoomes small and snow or ice
adherence may easily occur. Further, in the daytime
during whioh the power transmission amount is lar~e, it
does not aooelerate temperature rise of the overhead
electrio wire.
EMBODIMENT 1
A~ shown in Fig. 1, a heat-generative eleotrio wire
1 of this invention has a Ni-Fe series alloy wire member
3 wound on the outermo~t layer of a overhead eleotrio
.
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wire 2. The heat-generative electric wire 1 was formed
by winding the Ni-Fe serie alloy wire member 3
containing a variously ohanged amount of Ni on the
overhead electric wire 2 formed of aluminum conduotor
steel reinforced ~ACSR) having a cros~ sectional area of
610 mm2. The ~urface temperature of the alloy wire
member 3 at the time of oonducting ourrent through the
overhead electric wire 2 was measured.
The amount of Ni contained in the alloy wire member
3 was set to 3~, 40, 46, 51, 60, 70 and 80 X, seven kinds
of oold-extended wire members with a diameter of 2.6 mm
were prepared and were sequentially wound at a regular
interval on the overhead eleotrio wire 2 in a direotion
opposite to that of the stranding direction of the
outermost layer thereof. Then, as shown in Fi~. 2, the
heat-generative eleotric wire 1 having seven kinds of
alloy wire members 3 wound thereon was oonneoted to a
ourrent supplyin~ transformer 4. The surfaoe
temperatures of the alloy wire members 3 were measured
when A.C. ourrents of 100 A and 800 A were supplied to
the overhead eleotrio wire 2 in a thermostatio laboratory
kept at -4-C.
In this case, the alloy wire members 3 were wound on
the overhead eleotrio wire 2 at a distanoe of more than 1
m from one another ~o as to prevent the mutual thermal
influenoe. In measuring the surfaoe temperature, a
thermooouple was used and the surfaoe temperatures
measured by the thermooouple were reoorded by~use of a
ohopper bar type reoorder.
The result of the mea~uremént is shown in Fig. 3.
In Fig. 3, the absoissa indioates the oontent ~) of Ni
and the ordinate indioates the surfaoe temperature (~)
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of eaoh alloy wire member 3. A~ is olearly understood
from Fig. 3, in the heat-generative electrio wire 1 of
thi~ invention having the Ni-Fe series alloy wire member
with the Ni content of 45 to 80 % wound thereon, the
~urfaoe temperature of each alloy wire member 3 wa~
raised to suoh a temperature as to melt snow, that i8, to
10 to 18 C even when the amount of ourrent supply waY as
small as 100 A. Further, when the powe~r transmisslon
amount was as large as 800 A, the surfaoe temperature of
eaoh alloy wire member 3 was fell in a temperature ran~e
of 20 to 45 C.
In oontrast, in the heat-generative eleotrio wire
having the Ni-Fe series alloy wire member with the Ni
oontent of 35 or 40 % wound thereon, the temperature was
exoessively raised when the power transmission amount was
large, and the surfaoe temperature was extremely lowered
when the power transmission amount was small. The
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surface temperatures of the alloy wire member 3 were
respectively approx. 2 C and 3 C when the power
transmission amount was 100 A, and re~peotively approx.
140 C and 80 ~ when the power transmission amount was
800 A.
Further, as shown in Fi~. 4, eaoh of the alloy wire
members 3 was wound on the overhead eleotric wire 2 in a
stranding direotion of the outermost layer. The surfaoe
temperature of eaoh alloy wire member 3 was measured in
the same manner a~ in the former embodiment. As the
result, substantislly the same result as in the former
embodiment was obtained. There ooourred no differenoe in
the amount of generated heat even when the Nl-Fe series
alloy wire member 3 was wound on the overhead electrio
wire in any dlreotion with respeot to the stranding
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direction of the outermoist layer thereof.
In the above embodiment, the heat-generative
electric wire 1 was explained with the Ni-Fe series alloy
wire member 3 wound on the outermo~t layer of the
overhead electric wire 2, but the same snow melting
effect a~ in the case wherein the Ni-Fe series alloy wire
member was wound could be obtained when the Ni-Fe ~erie~
alloy wire members 3 were stranded with strands 2a
con tituting the outermost layer of the overhead electric
wire 2 as shown in Fig. 5. In a case where the alloy
wire members 3 are stranded with the strands 2a, it is
pre~erable to equally distribute the Ni-Fe series alloy
wire members 3 of the number corre~ponding to 1~4 to 1/2
of the number of the strands 2a oonstituting the
outermost layer.
Further, in the above embodiment, a oircular-form
wire having a oiroular seotion is used as the Ni-Fe
series alloy wire member 3, but a wire of a desired form,
suoh as a wire having a reotangular seotion or a tape-
like wire, oan be used.
EMBODIMBNT 2
Cold-drawing wire members oontaining Ni of 50.6 to
52 X, Mn of 0.20 to 0.35 X, Si of less than 0.20 % and Fe
as the remaining portion and having a diameter of 2.6 mm
were used as the alloy wire member 3, and Zn ooatings are
formed to a thiokness of 0.035 mm on the alloy wire
member 3 by plating. The alloy wire members 3 were wound
on the overhead eleotrio wire 2 oonstruoted in the same
manner as in the embodiment 1 in a direotion opposite to
that of the strandin~ direotion of the outermost layer
thereof. Then, the overhead eleotrio wire 2 was
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connected to the current supplying transformer 4 shown in
Fig. 2 under the same measurement oondition as in the
embodiment 1, and A.C. currents of 50 A, 80 A, 100 A, 150
A and 200 A were supplied thereto. Then, a temperature
rise ~T which i~ a difference between the room
temperature (-4 Cj and the surface temperature of the
alloy wire member 3 after the ourrent supply was
measured.
The result is shown in Fig. 6 together with the
measurement result used as a oompariaon example and
relating to the heat-generative eleotrio wire having the
alloy wire member 3 with no Zn coating and of the ame
oomposition wound thereon. In Fig. 6, the absoissa
indioates a ourrent value ~A), the ordinate indioates the
temperature rise ~T (-C), and the results of this
invention and the comparison example are respectively
indicated by ~ and 0. As is clearly seen from Fig. 6,
in the heat-generative electric wire, the heat generation
amount increases by approx. 20 X at maximum when the Zn
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coatings are formed on the alloy wire members 3, and thus
the snow or ice melting effeot oan be enhanced.
Further, antirust tests in whioh salt water was
sprayed onto the heat-~enerative eleotrlo wire 1 having
the alloy wire members 3 with Zn ooatin~s and the alloy
wire members of the aame oomposition without Zn ooatings
for 1500 hours while currents (100 A) were supplied to
them were effected. As the result, in the case of the
heat-generative electrio wire 1 having the alloy wire
members without Zn coatings, an electrolyte corrosion
phenomenon occurred between the overhead electrio wire 2
and the alloy wire member, and much rust occurred in the
overhead electric wire 2, thus reducing the effective
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diameter. On the other hand, in the case of the heat-
generative electric wire 1 having the alloy wire member~
3 with Zn coating~, the wster repellenoy was enhanced and
occurrence of ru~t due to the eleotrolyte corro ion wa~
not observed.
8MBODIMENT 3
Fig. 7 ~how~ an embodiment in whioh the alloy wire
member 3 i~ pre-formed in a spiral form with a preset
pitch, and this alloy wire member 3 i~ preferable~since
it oan be rapidly mounted on an overhead electrio wire 2
whioh has already been oonstruoted, for example.
Alloy wire members 3 having variou~ pitches from 1.5
up to five times the diameter D of the overhead electric
wire 2 and previou~ly formed in a spiral form were
prepared. They were mounted on the respeotive overhead
eleotric wires 2 having a cross seotional area of 610 mm2
and formed in the same manner as in the embodiment l aQ
shown in Fig. 7. A temperature rise ~T caused when an
A.C. ourrent of 100 A was supplied was measured.
A heat generation oharaoteristio ourve obtained as
the result is shown in Fig. 8. In Fig. 8, the ab~oi~sa
indioates a windin~ pitoh P ~mm) expres~ed by the
multiple of the diameter D (mm) and the ordinate
indioates the temperature rise T (~). The winding
pitoh P was set to 1.3D, 1.6D, 2.1D, 2.6D, 3.0D, 3.3D,
4.2D and 4.9D.
Assuming that the temperature ri~e ~T due to
current supply is 9 ~ in order to attain heat generation
amount required for melting snow or ioe attaohed to the
eleotrio wire, then, a~ seen from Fig. 8, the pitoh P
(mm) at whioh the alloy wire member 3 is wound on the
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overhead electric wire 2 is preferably set in the range
of 1.5 to 3 times the diameter D of the overhead eleotric
wire 2 indicated by an arrow in Fi~. 8.
However, in a case where the winding pitch P iq less
than 1.5 time~ the diameter D, it becomes difficult to
mount it on the overhead electric wire 2. On the other
hand, in a case where the pitch P exceeds three times the
diameter D, the heat generation amount is abruptly
reduced, oausing an undesirable result. Further, if Zn
coatings are previously formed on the pre-formed alloy
wire members 3, the water repellenoy and oorrosion
re~istanoe thereof can be enhanced.
Further, a plurality of alloy wire members 3, for
example, as shown in Fig. 9, three alloy wire members 3
can be integrally pre-formed in a spiral form with a
pitch of 1.5 to 3 time~ the diameter D of the overhead
electrio wire 2. In addition, the three alloy wire
members 3 integrally pre-formed in a spiral form oan be
formed Zn coatings on the surface thereof.
In eaoh of the above embodiments, if protection
members 5 shown in Figs. 10 and 11 are mounted on both
ends of the alloy wire member 3 wound on the overhead
electrio wire 2, it i~ preferable in proteotion for the
overhead eleotrio wire 2.
The proteotion member 5 is formed of semi-spherioal
half-divided bodies 6 and 7 coupled by use of a hinge.
The half-divided bodies 6 and 7 respectively have
reoesses 6a and 7a formed in the respeotive inner
portions, and they are ooupled by a bolt 8 and a nut 9
fixed in grooves 6b and 7b formed in the outer central
portions thereof. The proteotion member 5 is disposed to
shield the end of the alloy wire member 3 arranged as
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~hown in Fig. 10 with the recesses 6a and 7a previously
filled with filler 10 such as grea~e, ~ilicone-serie~
filler or the like.
Occurrence of corona discharge between the overhead
electric wire 2 and the alloy wire member 3 can be
prevented by mounting the protection member 5. Further,
the alloy wire member 3 wound on the overhead electric
wire 2 can be prevented from becoming loo~e.
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