JPS6148908A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To protect effectively from transient overvoltage of surge voltage and the like by a method wherein a nonlinear resistance element is connected between a neck section of a cooling duct and a member with potential. CONSTITUTION:A low voltage winding 4 and a high voltage winding 5, which are lapped to a metallic sheet 2 and an insulating sheet 3 at the leg section of a core, are wound and a hollow state cooling duct 6 is self-contained inside the winding 4 and 5. The cooling duct 6 is connected to a liquid-guide pipe 9 through an insulative pipe 8 from the neck section 7 of the said duct. The plural nonlinear resistance elements 12 is connected in the state of lamination among the neck section 7, the liquid-guide pipe 9, whick comes to be earth potential, such as a core cramping 10 and a tank 11. As the cooling duct 6 is the same electric potential as an adjointed winding, the nonlinear resistance element 12 functions most effectively and so can suppress sufficiently transient over-voltage such as surge voltage which invades from outside.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a foil-wound transformer that uses a winding formed by overlapping metal sheets and insulating sheets and has a cooling duct built into the winding. In particular, the R311 is applied to an 83-turn transformer with improved winding protection means to withstand transient overvoltages such as surge voltages that enter the windings.

[Technical background of the invention and its problems] A foil-wound transformer is characterized by its good space for eight wires and its ability to be made smaller and lighter. It has already been put into practical use in small wholesale transformers with relatively low voltages of several kilovolts and around 100 kilovolts. As is well known, in conventional small-capacity, low-voltage transformers, a lightning arrester is installed outside the transformer to protect the lines from the intrusion of transient overvoltages such as surge voltages. , was sufficiently effective. In addition, since such small-capacity, low-voltage foil-wound transformers are used for power distribution, they have a transport limit of 5 tons, t S, and 4
There was no need to worry.

However, with recent technological advances, the cold efficiency of foil-wound transformers has been greatly improved, for example at 275KV,
300 MV A tJ1 or 5oOK■, 750
With the development and research of foil-vinyl transformers such as M△ Ta.

For J5 substation transformers of this class, the lightning arrester should be installed as close to the transformer windings as possible in order to effectively suppress transient overvoltages such as surges. It is most desirable to mount the lightning arrester inside the transformer.

However, in conventional transformers that use rectangular conductors, it is relatively easy to install lightning arresters between sections of the windings because there is plenty of space, and it was thought that it could be applied. In the foil transformer d, since the metal sheath 1- and the insulation sheath 1- which surround the windings are tightly spring-wound, it is difficult to incorporate a lightning arrester between the windings.

Therefore, in side-winding transformers, the arrester is still installed externally, which prevents transient overvoltage from entering.
The windings were destroyed, reducing the reliability of the transformer, and an external lightning arrester had to be installed. Furthermore, since large-capacity foil-wound transformers are used for voltage transformation, they must meet the limits of railway transport, and from this point of view as well, there has been a demand for smaller transformers.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to provide an economical and insulating method that enables effective protection of windings against the invasion of transient overvoltages such as surge voltages. Is it highly reliable and compact? 3 is to provide a transformer.

[Summary of the Invention] The foil-wound transformer of the present invention has a coil-wound transformer by connecting a resistive element in a non-straight line 11 between the cooling duct neck and a member having a ground potential of a tank or liquid collection pipe. Non-direction tQ Il
, r, so as to be able to incorporate a resistor element (this is what was done).

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In the foil-wound transformer shown in Figure 4X1, the legs of core 1 are wound with low-voltage winding 4 and fungus winding 5, which are made by overlapping metal sheaths 1-2 and insulating sheaths 1-3. Inside these windings are 1 and 21 hollow-shaped cold coils 6. Cooling Goku 1
A refrigerant such as Freon R-113 or Fluorinert FC75 is sealed in the thin gap in the hollow part of 35i2. 2J! -! II'.

The cooling duct 6 is connected to a liquid guide pipe through a neck 7J, a pipe 8, and a pipe 8. Clamp 1○
It is also connected to the ground potential of the tank 11 and the like. On the other hand, the cooling duct 6 has a recessed top built into the winding.
It is electrically connected to the same potential as the adjacent winding. This cooling duct 6 is provided in multiple layers within the winding every several turns.

In such a foil-wound transformer, in particular, in this embodiment, the portion 7 of the cooling duct 6 and the liquid guide pipe 9 which is at ground potential are
A plurality of non-linear resistance elements 12 are connected in a layered manner between the iron core clamp 10 or the tank 11. As the non-linear resistance element 12, for example, a lightning arrester using a zinc oxide element is used.

Furthermore, 8F! Insulation of each part is ensured by an insulating medium such as Sr6 gas sealed in the tank 11 together with the contents of the transformer as described above.

The operation of this embodiment having the above configuration is as follows.

First, the neck 7 of the cooling duct 6 to which the non-linear resistance element 12 is connected is as close as possible to the winding, and the cooling duct 6 is at the same potential as the adjacent winding. J-3, a non-linear 1 degree resistor 12 will be connected in close proximity to the winding. Therefore, the non-ii+'1 wire resistance element 12 is Ω6
It functions effectively and infiltrates from the outside! Transient overvoltage such as surge voltage can be sufficiently suppressed i+jy.

In addition to protecting the valley wire by minimizing the generation of excessive pressure that flows into the winding, it is possible to accurately predict the value of overvoltage that will be applied to J3 in 5th embryo J, so it is possible to Compared to the foil-wound transformer, the reliability of the T8 edge is significantly higher.L, the winding insulation can be significantly reduced, and the economical efficiency is also improved.

In particular, when an insulating gas such as SF6 gas is used as the insulating medium, it has the effect of suppressing the arc that occurs on the surface of the stacked nonlinear resistance cords 12 when a surface bonding current flows. , there is no fear of deterioration of the non-linear resistance element and decrease in performance, and even better effects can be expected.

By the way, in a transformer with 31 turns per hour, special means for supporting the winding wire is required around the outer periphery of the leg of the tλ core, and there is a possibility that the winding support structure itself becomes a weak point in terms of insulation. When the non-linear resistance element 12 is attached to the lower part of the winding as in this embodiment, in order for the non-linear resistance element 12 to support the winding, the a-sized winding support structure of the insulating Buddha 11111- is
9. Moreover, in a foil-wound transformer in which a cooling panel is wound, the thickness of the cold part duct 6 is thicker than the metal sheet 2 and the insulation sheets 1 to 3, and the weight is added. However, in this embodiment, a part of the cold part 1 is directly supported, so there is a risk of the winding falling off due to vibration or short-circuit mechanical force. , a winding support structure with greater mechanical strength is obtained.

In this embodiment, the upper and lower parts of the winding, and also the collector tube 9\b iron core clamp 10, which is a member that takes earth potential,
Although non-linear resistance cables 12 are connected to one tank 11 etc. at multiple locations within one transformer, the non-linear resistance elements 12 are
It is sufficient to use as many as necessary for the transformer constant 13, etc.

Next, what is not shown in FIG. 2 is the second part of the foil-wound transformer of the present invention.
It is a partially enlarged view showing an example. In this embodiment, a non-linear resistance element 12 is formed in an annular shape, and a cooling duct 6 and a liquid collecting pipe 9 are disposed inside this I-shaped non-linear resistance element 12.
An insulated pipe 8 for connecting the cooling duct I and flowing the refrigerant is configured to an appropriate size, and a non-linear resistance element 12 is connected between the cooling duct I-neck 7 and the earth potential member. By configuring in this way, the non-linear resistance element 12 can be connected to the winding and the grounding part 1.
It can be installed efficiently in the space between two.

[Effect of the invention 1] As explained above, according to the present invention, by connecting a non-linear resistance element between the neck of the cooling duct and a member having a ground potential, it is possible to prevent the intrusion of transient overvoltage such as leakage voltage. It is possible to use a foil-wound transformer that provides the most effective protection of the windings, has poor insulation reliability, and allows for a smaller set value I.

4. Drawing (7) f! X'i '4i Explanation FIG. 1 shows an embodiment of the foil-wound transformer of the present invention.
The figure is an enlarged sectional view of an Ishinomaki transformer showing another embodiment of the present invention.

1...i legs of human heart, 2...gold 1'] S sheet, 3
... Insulation sheath 1-14 ... Low voltage conductor, 5 ... Hatake pressure winding, 6 ... Cooling duct, 7 ... Cooling duct neck,
8... Insulated pipe, 9... Liquid guiding pipe, 1o... Iron core clamp, 11... Tank, 12... Non-linear resistance element.

Claims (5)

[Claims] (1) In a foil-wound transformer, which uses a foil-shaped winding made of a metal sheet and an insulating sheet wrapped in layers, the transformer has a cooling duct built into the winding, and the contents of the transformer are enclosed in a tank together with an insulating medium. . A foil-wound transformer, characterized in that a non-linear resistance element is connected between a cooling duct neck protruding from the cooling duct to the outside of the winding and a member having a ground potential. (2) The foil-wound transformer according to claim 1, wherein the nonlinear resistance element is a lightning arrester using a zinc oxide element. (3) The foil-wound transformer according to claim 1, wherein the non-linear resistance cord is connected between the neck of the cooling duct and the transformer tank maintained at ground potential. (4) Claims in which the non-linear resistance element is connected between the neck of the cooling duct and a liquid collection pipe that is provided to collect refrigerant from the cooling duct and is maintained at ground potential. The foil-wound transformer according to item 1. (5) The non-linear resistance element has an annular shape, and an insulated pipe is inserted into the annular non-linear resistance element to flow the refrigerant from the neck of the cooling duct to the liquid collecting pipe. foil-wound transformer.