JPS61150207A - Transformer - Google Patents

Abstract

PURPOSE:To prevent a high voltage side coil from dielectric breakdown by a method wherein an electric potential fixing plate is wound from an inside peripheral face to an outside peripheral face of cooling duct, and the electric potential fixing plate are connected with an end of final winding and an end of initial winding at an intermediate section of the high voltage side coil. CONSTITUTION:A high voltage side coil 6 is provided with an annular cooling duct 12, which penetrates in axial direction, and an electric potential fixing plate, which is wound covering from an inside peripheral face to an outside peripheral face of the cooling duct at the intermediate position of the winding layer thereof and the cooling duct 12 is formed inserting plural pin-state spacer member 14... made of an insulated substance between the layers of the high voltage side coil 6. The said coil 6 is divided to an inside part and an outside part by the cooling duct 12 and they are high voltage side coil part 6a and 6b. The end of final winding at the inside coil part 6a thereof is connected with one end of the secondary electric potential fixing plate 13, on the other hand, the end of initial winding at the outside coil part 6b is connected with another end of the secondary electric potential fixing plate 13, then the end of final winding at the inside coil part 6a and the end of initial winding at the outside coil part 6b are kept at the almost same electric potential. Thereby, electric potential allotment in a coil of surge voltage generated at high voltage load side is evened off, the dielectric breakdown of the high voltage side coil can be prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to small current, high voltage transformers, such as test transformers, and particularly to voltage surges caused by flash faults on the load side. Concerning transformers that have taken protective measures.

<Prior Art> Conventionally, as shown in FIG. 6, for example, as shown in FIG. A potential fixing plate 5 made of a conductive material is wound on the winding form 2 so as not to form one turn, and the winding start end of the coil is connected to the potential fixing plate 5. The coil and the interlayer insulating sheet are alternately wound on the shape 2 to form a high voltage side wire ring 6, and the end of the winding of this high voltage side wire ring 6 is connected to a high voltage wire provided on the outermost periphery of the high voltage side wire ring 6. It is known that the transformer is connected to the shield 7 and the high voltage terminal 8 to form the contents of a transformer, and the transformer is housed in a pressure vessel (not shown) filled with insulating gas.

In such a conventional transformer, in order to efficiently dissipate Joule heat generated inside the high voltage side coil 6 formed in multiple layers when high voltage is induced, the middle part of the winding layer of the high voltage side coil 6 is For example, a plurality of spacer members (not shown) are interposed at predetermined pitches in the central portion of the high-voltage side line 6 to form an annular cooling duct 12 passing through the high-voltage side line 6 in the axial direction. Insulating gas is also allowed to flow inside the ring 6.

<Problems to be Solved by the Invention> FIG. 7 schematically shows an equivalent circuit of the high-voltage side track 6 in this case. In this figure, a capacitance Ca is formed between each layer of the high-voltage side track 6, and a capacitance Cb is also formed between the layers of the cooling duct 12 portion.

In this case, the interlayer distance in the cooling duct 12 portion is, for example, about 20 to 30 times larger than the interlayer distance in the high-voltage side track 6, and the dielectric constant of the insulating gas flowing in the duct is higher than that of the interlayer insulating sheet. Since it is, for example, about 1/3, the interlayer capacitance cb of this portion is extremely small, about 1760, compared to the other interlayer capacitances Ca. Therefore, this equivalent circuit and capacitance fic
a', the capacitance ratio of Cb.

As is clear from the above, the voltage applied between the layers of the cooling duct 12 is much higher than the voltage applied between the layers of the high-voltage side track 6.

For this reason, for example, if a surge voltage occurs due to sample flashing on the load side connected to the high voltage side, a considerable high voltage will be applied between the layers of the cooling duct 12, causing penetration and creeping. Both insulation breakdowns occur in this cooling duct 1.
There is a risk that the high-voltage side track 6 may be damaged due to the formation of a gap between the two layers.

In view of such conventional problems, the present invention provides a transformer having a high-voltage side coil in which a cooling duct is formed in the middle of the winding layer. The purpose is to equalize the potential sharing and prevent dielectric breakdown of the high-voltage side wheels.

<Means for Solving the Problems> In order to achieve the above object, the present invention includes a potential fixing plate wrapped around the cooling duct from the inner circumferential surface to the outer circumferential surface, and a high voltage side wire is attached to the potential fixing plate. It is characterized by a configuration in which the end of the winding and the beginning of the winding in the middle part of the ring are connected.

<Function> Similar to FIG. 7, FIG. 1 schematically shows an equivalent circuit of the high-voltage side rail of the structure. In this figure, inner and outer high-voltage side track portions 6 facing each other across the cooling duct 12 are shown.
Since a and 6b are kept at almost the same potential by the potential fixing plate 13, the glabellar capacitance cb of the cooling duct portion
is set to be approximately the same as the other layer gate capacitances Ca...

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings. In this example, the present invention is applied to a transformer for gas insulation testing.

FIG. 2 is a partially broken pressure surface view of the transformer of this example,
FIG. 3 is an enlarged sectional view showing the main parts,
FIG. 4 is a perspective view showing the high-voltage side track in the middle of formation. In these figures, reference numeral 1 indicates an iron core made of silicon steel plate or the like. A winding form 2 is attached to a part of this iron core l, and on this winding form 2, for example, a coil (not shown) made of a synthetic resin-coated copper wire and an interlayer insulation sheet (not shown) made of a plastic film sheet are mounted. A low-voltage side wire ring 3 is formed by alternately winding. The winding start end and winding end of this low-voltage side wire ring 3 are each connected to a low-voltage terminal (not shown).

A winding 4 is mounted on the low-voltage side wire ring 3, and a first potential fixing plate 5 made of a conductive thin plate of copper, aluminum, etc. is arranged so as not to form one turn on the winding 4. Can be wrapped. On this first potential fixing plate 5, a multilayer high voltage side coil 6 is formed by alternately winding coils similar to those of the low voltage side coil 3 and interlayer insulation sheets. A high voltage shield 7 and a high voltage terminal 8 are provided on the outermost periphery of this high voltage side wire ring 6.
is provided, and the winding end of the high voltage side wire ring 6 is connected to this high voltage shield 7. Further, the winding start end of the high voltage side wire ring 6 is connected to the first potential fixing plate 5, and is connected to the ground side terminal lO via a lead wire 9 drawn out from the first potential fixing plate 5. be done. The contents of the transformer configured in this way are housed in an iron pressure vessel 11 filled with a nonflammable insulating gas such as sulfur hexafluoride (SF'). - In a transformer having such a basic structure, the high-voltage side coil 6 has an annular cooling duct 12 penetrating in the axial direction in the center of its winding layer, and.

A potential fixing plate is wound around the cooling duct from the inner circumferential surface to the outer circumferential surface. The cooling duct 12 is formed by interposing a plurality of pin-shaped spacer members 14 made of an insulating material between the layers of the high-voltage side raceway 6.

Further, the second potential fixing plate 13 is constituted by a strip-shaped thin plate made of a conductive metal material such as copper or aluminum. The winding end of the inner coil portion 6 a of the high-voltage side coil portions 6 a and 6 b divided into inner and outer portions by the cooling duct 12 is connected to one end of the second potential fixing plate 13 ,
In addition, the winding start end of the outer coil portion 6b is connected to the other end of the second potential fixing plate 13, whereby the inner coil portion 6b is connected to the other end of the second potential fixing plate 13.
The end of winding a and the beginning of winding of outer wire portion 6b are kept at approximately the same potential.

The cooling duct 12 and the second potential fixing plate 13 are formed simultaneously when the high-voltage side wire ring 6 is wound. That is, as shown in FIG.
After connecting this coil to the insulating sheet, the coil and the insulating sheet are alternately wound until the diameter of the high-voltage side wire ring 6 becomes approximately half the diameter at the end of winding.

Next, one end of the coil is cut to form the inner coil portion 6a, and the winding end of this coil is connected to one end of the second potential fixing plate 13, and then the potential fixing plate 13 is connected to the inner coil portion 6a. Wind only one round of 6a. At this time, as shown in FIG. 5, the plurality of spacer members I4 are attached at predetermined pitches to the outer surface of the right side of the potential fixing plate 13 via double-sided adhesive tape 15 prepared separately. Paste it.

Further, the second potential fixing plate 13 is attached to each spacer member 14.
...Layer it on top and wind it for about one turn, and this potential fixing plate 1
The winding start end of the coil is connected to the other end of 3, and the coil is alternately wound with an insulating sheet to form the outer wire ring portion 6b.
form. Cooling duct 12 formed in this way
The radial dimension is set, for example, to about 20 times the interlayer dimension.

Note that this insulating sheet may be cut at one end along with the coil after the formation of the inner coil portion 6a is completed, and then wound again from the beginning of winding of the outer cut portion, or alternatively, it may be directly wound at the second potential from the beginning of winding of the high-voltage side coil portion 6. It may be wound over the fixed plate 1'3.

Further, the second potential fixing plate I3 can be modified in various ways, such as being constructed by connecting a plurality of rectangular plate pieces with wires made of a conductive material.

Further, the spacer members 14 may be made of a conductive material instead of the above-mentioned insulating material, and each spacer member 14 may be welded to the second potential fixing plate 13 in advance and then sandwiched between wire rings. However, in this case, the second potential fixing plate 13 and the insulating sheet are wound in an overlapping manner.
゛In the above embodiment, the cooling duct 12 is provided at one location in the center of the high-voltage side track 6, but if necessary, the high-voltage side track 6 may be divided into multiple stages, and between each stage there is a cooling duct 12 in the same manner as described above. It is also possible to form the cooling duct 12 with the following configuration.

<Effects of the Invention> As described above, according to the present invention, in order to efficiently dissipate Joule heat generated inside the high-voltage side wire, a cooling duct is formed in the middle part of the winding layer of the wire. Since a potential fixing plate is provided along the cooling duct to keep the winding end and the winding start end of the wire ring inside and outside the duct at almost the same potential, The potential distribution of the surge voltage within the wire ring is averaged, and dielectric breakdown of the high voltage side wire ring can be prevented.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is an equivalent circuit diagram schematically showing the high-voltage side track of a transformer according to the present invention, and FIG. 2 is an equivalent circuit diagram of the transformer according to this embodiment. Partially fractured pressure surface view, Figure 3 is an enlarged sectional view showing the main part, Figure 4
5 is a perspective view showing the process of attaching and fixing a spacer member to a potential fixing plate; FIG. 6 is a sectional view of a main part showing a conventional example; 7
The figure is an equivalent circuit diagram schematically showing the conventional high-voltage side track shown in FIG. Outside track ring part of lateral track ring, 12...
- Cooling duct, 13...potential fixing plate.

Claims (1)

[Claims] (1) A transformer in which a cooling duct is formed in the middle part of the winding layer of a high-voltage side coil, and a potential fixing plate is wound around the cooling duct from the inner circumferential surface to the outer circumferential surface, and the potential fixing plate is wrapped around the potential fixing plate. is a transformer in which the end of the winding and the beginning of the winding in the middle part of the high-voltage side wire ring are connected.