JPH11113245A - Thyristor valve module and insulating bolt for use therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent corona discharge at cooling fins even during use at high voltage, by installing an electrical stress relaxing section at both the ends of each guard electrode, and electrically connecting the electrical stress reducing section with the respective cooling fins. SOLUTION: A module is formed by alternately placing thyristors 1 and cooling fins 2, installing valve reactors or the like in series, clamping them between retaining members 3 of insulator, and fastening them together using insulating bolts 4. A width L of each guard electrode 44 is made larger than a distance L' between the guard electrodes 44, and electrical stress reducing sections 45 are formed at both ends. The cooling fins 2 are electrically connected with the guard electrodes 45 using bonding wires W. Therefore, the potential of the cooling fins 2 is applied to each guard electrode 44, and thyristor voltage is exerted on between the guard electrodes 44 with creeping electrical stress acting on the surface of the resin insulating layer. Since the electrical stress reducing sections 45 are formed at the guard electrode ends, the creeping electrical stress can be reduced. As a result, the occurrence of corona discharge at the surfaces of the cooling fins can be sufficiently prevented even at high voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyristor valve module used for an AC-DC converter and power control, and an insulating bolt used for fastening the thyristor valve module.

[0002]

2. Description of the Related Art A thyristor valve is used for AC-DC conversion at an intermediate base in high-voltage DC transmission and mutual transmission between large-capacity systems, conversion between 50 and 60 cycles, and power control to an arc blast furnace. in use. In this thyristor valve, the valve module is assembled into a multi-stage structure using insulating posts, and is fired by a pulse transformer system, an optical indirect trigger system, or an optical direct trigger system to perform AC / DC conversion by rectification. In the valve module, as shown in FIG. 4, thyristors 1 'and cooling fins 2' are alternately arranged, valve reactors and the like are arranged directly, and these are sandwiched between holding members 3 ', 3' at both ends. The thyristor, the cooling fin, and the valve reactor are connected by fastening the two members 3 ', 3' with bolts 4 '. In order to prevent corona discharge on the surface of the cooling fins 2', the bolts 4 ' Is coated with a resin insulating layer 43 ', and guard electrodes 44' for each cooling fin 2 'are provided on the outer surface of the insulating layer.
4 'and each cooling fin 2' are electrically connected to eliminate the action of the lines of electric force between the cooling fin 2 'and the guard electrode 44', thereby reducing the electric stress on the surface of the cooling fin 2 '. It is known to carry out the method (JP-A-58-95832).

[0003]

The voltage applied to each thyristor 1 'acts between the adjacent guard electrodes 44', 44 'in the insulating bolt 4', so that the guard electrode 44 '. , it is necessary to take a 'sufficient insulation distance L ₀ between each other' 44. Thus, the distance L ₀ ′ between the guard electrodes 44 ′ and 44 ′ is considerably widened, so that the guard electrodes 4 ′
The width L ₀ of the cooling fin 2 ′ becomes considerably narrow, and it becomes difficult to completely fit the width of the cooling fin 2 ′ within the width L ₀ of the card electrode 44 ′. When a line of electric force is generated toward a portion not covered by the card electrode 44 ') and the voltage becomes high, there is a concern that corona discharge based on the line of electric force will occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling device in which a thyristor and a cooling fin are alternately arranged between holding members at both ends and fastened with bolts straddling between the holding members. An object of the present invention is to provide a thyristor valve module capable of well preventing corona discharge at a fin and an insulating bolt used for the thyristor valve module.

[0005]

In the thyristor valve module according to the present invention, thyristors and cooling fins are alternately arranged between the holding members at both ends and tightened with bolts straddling between the holding members. A resin insulating layer is provided, guard electrodes for each of the cooling fins are provided on the outer surface of the insulating layer, and electric stress relieving portions are provided at both ends of each guard electrode.
In this configuration, each guard electrode and each cooling fin are electrically connected. The insulating bolt used in the thyristor valve module according to the present invention is
The configuration is characterized in that both ends of the gate electrode are covered with a material having a higher dielectric constant than the resin insulating layer, or that a shield ring is attached to both ends of the guard electrode.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A shows a thyristor valve module in which thyristors 1 and cooling fins 2 are alternately arranged, and a valve reactor and the like are arranged in series.
These arrangements are sandwiched between insulating holding members 3, 3 and these holding members 3, 3 are fastened with insulating bolts 4,... Between the thyristor and the cooling fin, between the thyristor and the valve reactor. The thyristor and the bushing conductor are electrically connected with a strong contact pressure. In the above,
Although the thyristor 1 and the cooling fin 2 are separate bodies,
A thyristor with integrated cooling fins can also be used.

The thyristor valve module according to the present invention is characterized by an insulating bolt. FIG. 1B shows an example of the insulating bolt. In (b) of FIG.
Reference numeral 1 denotes a bolt body (metal) having screw grooves 42 at both ends.
Is engraved. Reference numeral 43 denotes a resin insulating layer provided on the outer surface of the bolt main body 41, which can be formed by casting an epoxy resin or winding a filament material of an epoxy resin impregnated fiber. A heat-shrinkable tube may be coated on the bolt body, and a resin insulating layer may be formed on the outer surface thereof. 4
Are guard electrodes provided on the outer surface of the resin insulation layer 43 for the cooling fins 2,.
The width L of the electrode 4 is larger than the distance L 'between the guard electrodes 44, and skirt portions 45 for reducing electric stress are provided at both ends of each guard electrode 44. The guard electrode with a skirt portion may be made of a conductive resin or rubber in addition to a metal.

The cooling fins 2 and the guard electrodes 44 are electrically connected by bond wires w. Accordingly, the potential of the cooling fin 2 bonded to the guard electrode 44 is applied to each guard electrode 44 of the insulating bolt 4, and a thyristor voltage (anode-electrode) is applied between the guard electrodes 44,44. The voltage between the cathodes acts on the guard electrodes 44, 44.
Creepage electric stress acts on the surface of the resin insulating layer between them. Since the electric stress relaxation portion 45 is provided at the end of the guard electrode and the creeping electric stress at the end of the guard electrode can be reduced, the distance L 'between the guard electrodes can be reduced. Also, creeping discharge on the surface of the insulating layer can be prevented accordingly, and the width L of the guard electrode 44 can be increased accordingly. As a result, generation of lines of electric force extending from the cooling fins 2 toward the bolt body 41 (substantially the ground potential) can be prevented well, and even under a high voltage, generation of corona discharge on the surface of the cooling fins can be sufficiently prevented. .

FIG. 2 shows another example of an insulating bolt used for the thyristor valve module. A resin insulating layer 43 is provided on the bolt body 41, and a groove 46 having both ends in a bell shape is cut and processed. Metallicon or conductive paint
To form a guard electrode 44, and the card electrode 44
Tape 47 having a higher dielectric constant than the resin insulating layer 41
(For example, a rubber or plastic tape to which a high dielectric constant powder such as titanium oxide or barium titanate is added) is wound to form an electric stress relieving portion.

FIG. 3 shows another example of the insulating bolt used in the thyristor valve module. Shield rings 48 (a metal tube ring, a spiral metal wire ring, etc.) are electrically provided at both ends. A bonded cylindrical metal electrode 44 of a metal mesh is buried in proximity to the bottom of a groove 46 having both ends bell-shaped.

In FIG. 1B, FIG. 2 and FIG.
Is the width of the guard electrode 44, and L 'is the guard electrode 44,44.
L> L ′. In each of the above insulating bolts ((b) in FIG. 1, FIG. 2, FIG. 3),
The distance between each guard electrode at the both ends and each end of the bolt body (thread grooves are engraved) can ensure insulation between the working potential of each guard electrode and the ground potential. Needless to say, the insulation distance is set to be sufficient.

[0012]

According to the present invention, in a thyristor valve module in which thyristors and cooling fins are alternately arranged between holding members at both ends and fastened with insulating bolts straddling between both holding members, an ultra-high voltage module is provided. Anyway, both corona discharge on the surface of the cooling fin and creeping discharge on the surface of the insulating layer of the insulating bolt can be well prevented, which is useful for a high-voltage thyristor valve.

[Brief description of the drawings]

FIG. 1 (A) is an explanatory view showing a thyristor valve module according to the present invention, and FIG. 1 (B) is FIG. 1 (A).
It is explanatory drawing which shows the insulating bolt in FIG.

FIG. 2 is an explanatory view showing one insulating bolt according to the present invention.

FIG. 3 is an explanatory view showing another insulating bolt according to the present invention.

FIG. 4 is an explanatory view showing a conventional thyristor valve module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thyristor 2 Cooling fin 3 Holding member 4 Insulating bolt 41 Bolt body 43 Resin insulating layer 44 Guard electrode 45 Electric stress relieving part 46 Groove 47 High dielectric constant material 48 Shield ring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Susumu Kiyohara 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Mitsuo Tan 1-2-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Akio Fukushima 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (3)

[Claims] A thyristor and a cooling fin are alternately arranged between holding members at both ends and fastened with bolts straddling between the holding members. The bolts are provided with a resin insulating layer, and the cooling member is provided on an outer surface of the insulating layer. A thyristor valve module characterized in that guard electrodes are provided for the fins, electrical stress relief portions are provided at both ends of each guard electrode, and each guard electrode and each cooling fin are electrically connected. . 2. The thyristor valve module according to claim 1.
An insulated bolt, wherein both ends of a guard electrode are covered with a material having a higher dielectric constant than a resin insulating layer. 3. The thyristor valve module according to claim 1.
An insulated bolt, wherein shield rings are attached to both ends of a guard electrode.