JP2018055864A - Wire and laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire that can suppress corona discharge.SOLUTION: An insulation tube 104 has a substantially fixed thickness, and changes the diameter periodically in lengthwise direction. A conductor 102 is inserted into the insulation tube 104. An outside tube 106 has conductivity, with the insulation tube 104 inserted into the outside tube.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a high voltage wiring.

  CV (crosslinked polyethylene insulated vinyl sheath) cables are widely used for transmission of high voltages exceeding several hundred volts. The CV cable has a multilayer structure of a conductor, an inner semiconductive layer, a crosslinked polyethylene insulating layer, and an outer semiconductive layer.

  When voids are present in the insulating layer of the CV cable, corona discharge (partial discharge) due to electric field concentration occurs, and the deterioration of the CV cable is promoted.

Japanese Patent Laying-Open No. 2015-186418

  This invention is made | formed in view of this subject, and one of the illustrative objectives of the certain aspect exists in provision of the electric wire which can suppress a corona discharge.

  One embodiment of the present invention relates to an electric wire. The electric wire has a substantially constant thickness and has an insulating tube whose diameter changes periodically with respect to the length direction, a conductor inserted in the insulating tube, and conductivity, and has insulation inside. An outer tube into which the tube is inserted.

  According to this aspect, an air insulating layer is secured inside and outside the insulating tube. Corona discharge can be suppressed by determining the thickness of the insulating layer so as not to generate discharge in relation to the potential of the conductor. Note that in this specification, conductivity includes semiconductivity.

  The outer tube may be a metal pipe. That is, when it is desired to lay a conductor in the metal pipe, corona discharge can be suppressed by inserting an insulating tube between them.

  The insulating tube may be a corrugated tube. Generally, the cost can be reduced by diverting a corrugated tube used for protecting a CV cable or the like or assisting the laying as a member for securing an insulating layer.

  The outer tube may have a substantially constant thickness and the diameter may vary with a different period than the insulating tube. Thereby, the insulation between a conductor and an outer side tube can be improved further.

When the maximum value of the inner diameter of the insulating tube is r ₁ , the minimum value of the inner diameter is r ₂ , and the thickness is d, d / (r ₁ −r ₂ ) is equal to or less than a predetermined value at any location in the length direction. It may be. Thereby, corona discharge can be further suppressed.

  Another embodiment of the present invention relates to a laser apparatus. The laser device includes a pair of discharge electrodes and a high-frequency power source that generates an alternating high voltage applied to the pair of discharge electrodes. The wiring between the high-frequency power source and the pair of discharge electrodes may include any of the above-described electric wires.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to an aspect of the present invention, corona discharge can be suppressed.

FIGS. 1A and 1B are a cross-sectional view and a side view of the electric wire according to the first embodiment. FIG. 2A is a diagram showing the electric wire when the conductor and the outer tube are closest to each other, and FIG. 2B is an equivalent circuit diagram of FIG. In the electric wire of 1st Example, it is a figure explaining the problem which arises when an outer side tube is bent at right angle. It is sectional drawing of the electric wire which concerns on 2nd Example. It is a figure which shows the state which bent the electric wire of FIG. 4 at right angle. It is sectional drawing of the electric wire which concerns on 3rd Example. FIGS. 7A and 7B are diagrams showing a modification of the periodic structure employed in the insulating tube and the outer tube. It is a figure which shows a laser apparatus.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  The dimensions (thickness, length, width, etc.) of each member described in the drawings may be appropriately enlarged or reduced for easy understanding. Furthermore, the dimensions of the plurality of members do not necessarily represent the magnitude relationship between them, and even if one member A is drawn thicker than another member B on the drawing, the member A is the member B. It can be thinner.

(First embodiment)
FIGS. 1A and 1B are a cross-sectional view and a side view of the electric wire according to the first embodiment. In addition, in each drawing, only a part of the length direction of an electric wire is shown. The electric wire 100a is used for transmission of high voltage of several hundred V to several kV. The electric wire 100a includes a conductor 102, an insulating tube 104, and an outer tube 106. The insulating tube 104 has a substantially constant thickness d, and the diameter changes periodically with respect to the length direction. The conductor 102 is not covered and its surface is exposed to air, and is inserted into the insulating tube 104 so as to be deformable. The outer tube 106 has conductivity, and the insulating tube 104 is accommodated therein.

  For example, the outer tube 106 may be a metal pipe, and the insulating tube 104 may be a corrugated tube. In use, the outer tube 106 may be grounded or floating.

  The conductor 102 can be deformed inside the insulating tube 104 and can move in the radial direction. The insulating tube 104 can be deformed inside the outer tube 106 and can move in the radial direction.

FIG. 2A is a diagram showing the electric wire 100a when the conductor 102 and the outer tube 106 are closest to each other. The maximum value of the inner diameter of the insulating tube 104 is r ₁ , the minimum value of the inner diameter is r ₂ , and the thickness is d. At this time, an air layer having a thickness Δr = r ₁ −r ₂ and an insulating layer having a thickness d exist between the conductor 102 and the outer tube 106 at any position in the length direction.

FIG. 2B is an equivalent circuit diagram of the electric wire 100a of FIG. Between the conductor 102 and the outer tube 106, a series connection of a capacitor C _AIR formed by the air layer and a capacitor C _DIE formed by the insulating layer of the insulating tube 104 is formed. At this time, the voltage _{V AIR} applied to the capacitor _{C AIR} is
V _AIR = V × {(jωC _AIR ) ⁻¹ / {(jωC _AIR ) ⁻¹ + (jωC _DIE ) ⁻¹ }
= V × C _DIE / (C _DIE + C _AIR ) (1)

Further, when the relative permittivity of air is 1, the relative permittivity of the insulating tube 104 is ε, the thickness of the air layer is Δr, and the thickness of the insulating tube 104 is d,
C _AIR = ε ₀ × S / Δr (2)
C _DIE = ε ₀ × ε × S / d (3)
Get. Substituting equations (2) and (3) into equation (1) and rearranging results in equation (4). However, the area of the air layer and the insulating layer was assumed to be equal.

V _AIR = V × εΔr / (εΔr + d) (4)

The electric field E _AIR generated in the air layer is given by the following equation.
E _AIR = V _AIR / Δr (5)
Substituting equation (4) into equation (5) yields equation (6).
E _AIR = V × ε / (εΔr + d) (6)

Therefore, under the condition that the sum of the thicknesses of the air layer and the insulating layer is constant (Δr + d = R), the electric field of the air layer E _AIR can be reduced as Δr is increased, and the thickness Δr of the air layer is minimized. Therefore, corona discharge can be suppressed because no electric field concentration like voids occurs.

Preferably, d / Δr = d / (r ₁ −r ₂ ) is equal to or less than a predetermined value at any location in the length direction. For example, the predetermined value is preferably 20% or less, and more preferably 10% or less.

  Thus, according to the electric wire 100a which concerns on 1st Example, corona discharge can be suppressed suitably. In particular, a low-cost electric wire can be realized by diverting a corrugated tube used for protection of CV wiring or the like to the insulating tube 104.

  FIG. 3 is a diagram illustrating a problem that occurs when the outer tube 106 is bent at a right angle in the electric wire 100a of the first embodiment. When the outer tube 106 enters the recessed portion of the insulating tube 104 at the bent portion 110 indicated by the alternate long and short dash line, the distance between the conductor 102 and the outer tube 106 decreases. In the worst case, only the insulating tube 104 and a very thin air layer will be present between the conductor 102 and the outer tube 106. In this case, electric field concentration occurs in a thin air layer, and corona discharge may occur. In other words, the electric wire 100a according to the first embodiment is effective in a place where bending does not occur as shown in FIG.

(Second embodiment)
FIG. 4 is a cross-sectional view of the electric wire 100b according to the second embodiment. In the electric wire 100b, the outer tube 106 has a periodic structure similar to that of the insulating tube 104. The period L ₂ of the outer tube 106 is different from the period L ₁ of the inner insulating tube 104. If the periods L ₁ and L ₂ are equal, the probability that the convex part of one tube contacts the concave part of the other tube is increased for each period. On the other hand, by making the two periods L ₁ and L ₂ different, the probability that one convex portion comes into contact with the other concave portion can be reduced. For this reason, it is preferable that one period is 2 to 10 times the other period.

  FIG. 5 is a diagram illustrating a state where the electric wire 100b of FIG. 4 is bent at a right angle. As a result of introducing the periodic structure into the outer tube 106, the outer tube 106 can be prevented from coming into contact with the insulating tube 104 when the electric wire 100b is bent at a right angle. Thereby, a sufficiently thick air layer can be secured even in the bent portion 110, and corona discharge can be suppressed.

(Third embodiment)
FIG. 6 is a cross-sectional view of the electric wire 100c according to the third embodiment. In this electric wire 100 c, two layers of insulating tubes 104 and 108 are provided between the conductor 102 and the outer tube 106. The outer insulating tube 108 and the inner insulating tube 104 have different periods. According to the electric wire 100c, the insulation between the conductor 102 and the outer tube 106 can be further enhanced, and corona discharge can be further suppressed.

  In the above, this invention was demonstrated based on some embodiment. Those skilled in the art will understand that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. By the way. Hereinafter, such modifications will be described.

(Modification)
FIGS. 7A and 7B are diagrams showing modifications of the periodic structure employed in the insulating tube 104 and the outer tube 106. FIG. The tube in FIG. 7A has a trapezoidal cross-sectional shape, and the tube in FIG. 7B has a triangular cross-sectional shape.

  The period L and the amplitude of the insulating tube 104 (108) do not need to be constant, and may vary with respect to the length direction. This variation may be periodic or may have fluctuations. The same applies to the outer tube 106.

  In the electric wire 100b of FIG. 6, the outer tube 106 may have a periodic structure. At this time, the cycle of the outer tube 106 is different from the cycle of the insulating tube 108.

(Use)
Then, the use of the above-mentioned electric wire 100 is demonstrated. FIG. 8 is a diagram showing the laser device 200. The laser device 200 includes a direct current power source 202, a high frequency power source 204, and a light source 206. The DC power source 202 includes a noise filter 220 and a bank capacitor 222. The high frequency power supply 204 includes an inverter 232 that applies a high frequency voltage of about 500 V to the transformer 230 and the primary winding W1 of the transformer 230. A high-frequency high voltage of, for example, several kV (for example, 5 kV) is generated in the secondary winding W2 of the transformer 230. This high frequency high voltage is supplied to the light source 206 via the cables 210 and 212. The light source 206 is a CO ₂ laser, for example, and includes a pair of discharge electrodes 240 and a DC block capacitor 242. The electric wire 100 described above can be suitably used for the cables 210 and 212.

The power supply terminals to the pair of discharge electrodes 240 of the light source 206 are in the atmosphere. The electric wire 100 is connected to the power supply terminal through a CO ₂ gas chamber lower than the atmospheric pressure. A metal pipe is selected for the outer tube 106 so as to withstand this pressure difference. In this application, it is desirable that the outer tube 106 of the electric wire 100 used as the cables 210 and 212 is grounded.

DESCRIPTION OF SYMBOLS 100 ... Electric wire, 102 ... Conductor, 104 ... Insulating tube, 106 ... Outer tube, 200 ... Laser apparatus, 202 ... DC power supply, 204 ... High frequency power supply, 206 ... Light source, 240 ... Discharge electrode.

Claims (6)

An insulating tube having a substantially constant thickness, the diameter of which varies periodically with respect to the length direction;
A conductor inserted in the insulating tube;
An outer tube having electrical conductivity and having the insulating tube inserted therein;
An electric wire comprising:   The electric wire according to claim 1, wherein the outer tube is a metal pipe.   The electric wire according to claim 1 or 2, wherein the outer tube has a substantially constant thickness, and the diameter changes at a different period from the insulating tube.   The electric wire according to any one of claims 1 to 3, wherein the insulating tube is a corrugated tube. When the maximum value of the inner diameter of the insulating tube is r ₁ , the minimum value of the inner diameter is r ₂ , and the thickness is d, d / (r ₁ −r ₂ ) is a predetermined value or less at any location in the length direction. The electric wire according to claim 1, wherein the electric wire is formed. A pair of discharge electrodes;
A high frequency power source for generating an alternating high voltage to be applied to the pair of discharge electrodes;
And a wire between the high-frequency power source and the pair of discharge electrodes includes the electric wire according to any one of claims 1 to 5.

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