CA2013792A1

CA2013792A1 - Heat-generative electric wire

Info

Publication number: CA2013792A1
Application number: CA002013792A
Authority: CA
Inventors: Junichi Sasaki; Shuichi Higashida; Tooru Kojima
Original assignee: Individual
Current assignee: Furukawa Electric Co Ltd
Priority date: 1989-04-05
Filing date: 1990-04-04
Publication date: 1990-10-05
Also published as: KR900017050A; NZ233190A; EP0391719A1

Abstract

ABSTRACT OF THE DISCLOSURE

A heat-generative electric wire includes a Ni-Fe series alloy wire member which contains Ni of 45 to 80 %
by weight and the remaining portion of Fe and which is wound on or stranded with the outermost layer of an overhead electric wire. The Ni-Fe series alloy wire member wound on or stranded with the heat-generative electric wire has a sufficiently large heat generating amount even when the power transmission amount is small, thus exhibiting a snow or ice melting effect, and at the same time, it is not excessively heated even when the power transmission amount is large. Preferably, the Ni-Fe series alloy wire member is formed to have a metal coating formed on the surface thereof, and in this case, the heat generation amount of the alloy wire member is increased and electrolyte corrosion of the overhead electric wire can be prevented.

Description

2~79~

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 ~ ~, ~ ~" ' 1;
~ ~ :

:
,, :

---` 201379~

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 '` 2013792 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 , ~
'; ' -'` 2013792 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 ~ ' ' . ., ' ~ , . .

., . ... .. . .. - . ....
~: ,, : - : , . : . ..

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 ., ~ ~ ' " ' i ''' "''' '"' ' ' ' :

: ~ . ~ .: : ,. . : : :,, .

t 3 t 9 2 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.

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 .

. .

,. . , .. . . ~ . . .

. ! ' ' ~ .. ..

,, . , , ' ', 2~37~2 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 (~) -``` 20137~2 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 ,: ~
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 2~3;7~:

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.

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 ~3~

- 10 - ~

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 ,~, 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 2~3792 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.

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 ~ . - ' ! . , , . .;, , ,. ~, . ..

~ 20~L~7~2 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 - ; .
'~ : ~ ' ; , ' .

-- 20~37~'~

~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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Claims

1. A heat-generative electric wire characterized by comprising a Ni-Fe series alloy wire member which contains Ni of 45 to 80 % by weight and the remaining portion of Fe and which is wound on or stranded with the outermost layer of an overhead electric wire.

2. A heat-generative electric wire according to claim 1, wherein said Ni-Fe series alloy wire member contains Ni of 47 to 54 % by weight.

3. A heat-generative electric wire according to claim 1, wherein said Ni-Fe series alloy wire member contains Ni of 50 to 52 % by weight.

4. A heat-generative electric wire according to claim 1, wherein said Ni-Fe series alloy wire member has a metal coating formed on the surface thereof.

5. A heat-generative electric wire according to claim 4, wherein said metal coating is Zn.

6. A heat-generative electric wire according to claim l, wherein said Ni-Fe series alloy wire member wound on the outermost layer of said overhead electric wire is pre-formed in a spiral form with a preset pitch.

7. A heat-generative electric wire according to claim 6, wherein the winding pitch of said Ni-Fe series alloy wire member wound on said overhead electric wire is 1.5 to 3 times the diameter of said overhead electric wire.

8. A heat-generative electric wire according to claim 6, wherein said Ni-Fe series alloy wire member has a metal coating formed on the surface thereof.

9. A heat-generative electric wire according to claim 1, wherein said Ni-Fe series alloy wire member wound on the outermost layer of said overhead electric wire has a plurality of wire members integrally formed and is pre-formed in a spiral form with a preset pitch.

10. A heat-generative electric wire according to claim 9, wherein the winding pitch of said Ni-Fe series alloy wire member having a plurality of integrally pre-formed wire members and wound on said overhead electric wire is 1.5 to 3 times the diameter of said overhead electric wire

11. A heat-generative electric wire according to claim 9, wherein said Ni-Fe series alloy wire member having a plurality of integrally pre-formed wire members has a metal coating formed on the surface thereof.

12. A heat-generative electric wire according to claim 1, wherein said Ni-Fe series alloy wire member wound on the outermost layer of said overhead electric wire has a protection member mounted on the winding end of said heat-generative electric wire.

13. A heat-generative electric wire according to claim 6, wherein said Ni-Fe series alloy wire member has a protection member mounted on the winding end of said heat-generative electric wire.

14. A heat-generative electric wire according to claim 9, wherein said Ni-Fe series alloy wire member having a plurality of integrally pre-formed wire members has a protection member mounted on the winding end of said heat-generative electric wire.