KR101045651B1 - Compact pole transformer - Google Patents

Abstract

PURPOSE: A compact pole transformer is provided to have the properties of low cost and heat resist by performing complex insulation using two kinds of insulation papers in a first winding and a second winding. CONSTITUTION: An iron core is formed in a silicon steel plate inside the outer case of a compact pole transformer to make a magnetic circuit. A first winding(100) is wound in an iron core with a copper wire. A second winding(150) is wound in the iron core with an aluminum wire. A first insulation layer(110) is formed between the first winding and the second winding. A second insulation layer(160) insulates the winding wires of the first winding.

Description

Compact pole transformer

The present invention relates to a compact columnar transformer.

Domestic power consumption is increasing year by year, and the demand for electricity is increasing due to the urban density of the population.

Transformers should be developed in consideration of life, efficiency and capacity as well as aspects for stable power supply. In particular, the columnar transformer has a large number of installations, and because it is installed at the end of the load, economical and environmental considerations should also be considered.

Conventional column transformers are caused by internal insulation weakening and short circuit performance degradation, and varnishes are used to prevent such accidents. However, when the varnish is used, the mechanical strength is increased, but there is a problem that the transformer characteristics are degraded due to deterioration when used for a long time.

Conventional column transformer has a heavy weight using a copper wire in the winding portion, which is difficult to transport or install, and also has a disadvantage in that the heat resistance characteristics are deteriorated.

An object of the present invention is to provide a lightweight columnar transformer.

An object of the present invention is to provide a column transformer with reduced iron loss.

The problem to be solved of the present invention is to provide a column transformer having heat resistance characteristics.

The problem to be solved of the present invention is to provide an environmentally friendly column transformer.

An object of the present invention is to provide a columnar transformer with an external tap-changer.

According to one aspect of the invention, the transformer enclosure; An iron core formed of silicon steel sheet for forming porcelain in the transformer enclosure; A primary winding wound around the iron core in a copper wire; A secondary winding unit wound around the iron core with an aluminum wire; A first insulating layer formed between the primary winding and the secondary winding; A second insulating layer for inter-winding insulation of the primary winding; A third insulating layer for inter-winding insulation of the secondary winding part; And vegetable insulating oil for insulation of the transformer enclosure and the iron core, the primary winding portion and the secondary winding portion, wherein the silicon steel has a thickness of 0.23 to 0.27 mm and a density of 7.65 (g / cm ³ ). The silicon content of the silicon steel sheet may provide a columnar transformer having 2 to 4 parts by weight based on iron.

The iron core may be 3 parts by weight of silicon based on iron.

The primary winding part may be wound around the copper wire in a layer, and the first insulating layer may further include a first insulating paper for directly contacting and insulating the copper wire between the copper wire layers and a second insulating paper for non-contacting insulation with the copper wire. can do.

The first insulating paper may be an insulating paper having a higher maximum allowable temperature than the second insulating paper.

The secondary winding part may be wound around the aluminum wires in a layer, and the second insulating layer may be insulated from a third insulating paper that is in direct contact with the aluminum wires and insulates the aluminum wires between the aluminum wires. The insulating paper may further include.

The third insulating paper may be insulating paper having a higher maximum allowable temperature than the fourth insulating paper.

The transformer enclosure has a cylindrical sidewall; A lower surface formed under the sidewall; And a cover formed in a conical shape so as to face a center from a surface in contact with the side wall, and a hinge hinged to the side wall.

The cover may further include at least one concave portion formed concave in an inner direction of the transformer enclosure.

The lower surface protrudes outward of the transformer enclosure and may further include support means formed in a polygon.

The lower surface may further include a support means protruding outward from the transformer enclosure and having a plurality of support pieces divided therein.

The columnar transformer may further include heat dissipation means in contact with the side wall to dissipate the transformer enclosure.

The columnar transformer may include a high pressure bushing connected to the primary winding; And a low pressure bushing connected to the secondary winding.

The columnar transformer may further include a tap changer for adjusting a turns ratio of the secondary winding part, and the tap change part may be formed outside the transformer enclosure.

The columnar transformer may further include a protective cap formed to protrude outward from the transformer enclosure to protect the tap-changer.

The columnar transformer may further include a pressure release device on the opposite side of the tap-changer to reduce the pressure when the pressure rises inside the transformer enclosure and return when the pressure decreases below a predetermined pressure.

The columnar transformer may further include a pair of lifting rings located on the center of gravity of the transformer outside the transformer enclosure.

According to an embodiment of the present invention, the weight of the transformer can be reduced by using aluminum wires in the secondary winding part.

According to the embodiment of the present invention, the iron core can be made of silicon steel sheet to reduce the iron loss.

According to the embodiment of the present invention, the composite winding is implemented by using insulating paper having two kinds of maximum allowable temperatures in the primary winding portion and the secondary winding portion, thereby providing a columnar transformer having low cost and heat resistance characteristics.

According to the embodiment of the present invention, it is possible to provide an environmentally friendly columnar transformer using vegetable insulating oil.

In addition, according to the embodiment of the present invention, it is possible to increase the service life by improving the durability of the transformer by using the composite insulating and vegetable insulating oil.

According to the practice of the present invention, it is possible to provide a columnar transformer having an external tap-changing part that can work even in rainy weather.

And according to the embodiment of the present invention, it is possible to provide a columnar transformer that can prevent the penetration of moisture by using a conical cover.

1 is a perspective view showing a column transformer according to an embodiment of the present invention.
2 is a cross-sectional view showing a cross section of the columnar transformer shown in FIG.
3 is a perspective view showing an embodiment of the iron core inside the columnar transformer shown in FIG.
Figure 4 is a perspective view for explaining the insulating paper of the primary winding portion and the secondary winding of the present invention.
FIG. 5 is a sectional view showing a section of the primary and secondary windings shown in FIG. 4; FIG.
FIG. 6 shows the top surface of the columnar transformer shown in FIG. 1; FIG.
Figure 7 is a side view of the cover of the transformer enclosure shown in Figure 6;
8 to 11 are plan views illustrating lower surfaces of a transformer enclosure according to an exemplary embodiment of the present invention.

The present invention may be variously modified and have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail with reference to the accompanying drawings. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, numerals (eg, first, second, etc.) used in the description process of the present specification are merely identification symbols for distinguishing one component from another component.

In addition, in the present specification, when one component is referred to as "connected" or "connected" with another component, the one component may be directly connected or directly connected to the other component, but in particular It is to be understood that, unless there is an opposite substrate, it may be connected or connected via another component in the middle.

Hereinafter, a column transformer according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view illustrating a columnar transformer according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the columnar transformer illustrated in FIG. 1. The column transformer according to an embodiment of the present invention is described as an example of a 22.9kV general transformer, but is not limited thereto.

1 and 2, the columnar transformer according to an embodiment of the present invention may include a transformer enclosure 600, an iron core 300, a primary winding unit 100, a secondary winding unit 150, and a primary side bushing. 700, the secondary side bushing 800 and the tap changer 400 may be included.

Specifically, the transformer enclosure 600 may be embedded in the iron core, the primary and secondary windings 150. The transformer enclosure 600 may include a side wall 610, a bottom surface 680, and a cover 650, which will be described in more detail later with reference to FIGS. 6 to 11.

The transformer enclosure 600 may have a breakdown pressure and a dynamic pressure proof strength in order to prevent bursting, detachment, oil ejection, etc. of the enclosure due to an internal pressure increase. The static pressure withstand pressure does not cause deformation, including the 4.90 N / cm ² (0.5kgf / cm ² ) transformer cover 650, and the transformer enclosure 600 at 13.72 N / cm ² (0.5kgf / cm ² ) And it can satisfy the condition that the internal and external components are prevented from rupture, separation and the like.

In addition, the transformer enclosure 600 may have an arc gap of 2.5 mm therein and generate two arcs at 7.2 kV and 8 kA (rms, sym) between the gaps to maintain a normal state.

The transformer enclosure 600 may have an oil level display indicating the oil level of the insulated oil 500. For example, the transformer enclosure 600 may be formed with an oil level indication that may indicate an appropriate oil level position at an insulation oil temperature of 25 degrees.

The insulating oil 500 is embedded in the transformer enclosure 600. Insulating oil 500 may use a vegetable insulating oil. Insulating oil 500 uses a vegetable insulating oil that satisfies the vegetable insulating oil characteristics of Table 1.

Item Test specification Reference value Dielectric strength ASTM D-1816 ≥40 kV (2 mm Gap) Neutrality ASTM D-974 ≤0.06 mgKOH / g Lowering point ASTM D-92 ≥ 300 ℃ flash point ASTM D-92 ≥ 320 ℃ Viscosity ASTM D-445 40 ℃
100 ℃ ≤ 50cSt
≤ 15cSt Pour point ASTM D-97 ≤ -20 ℃ Water content ASTM D-1533 ≤ 200 ppm Toxicity Test OECD 203 No lethal, no peculiarities observed Biodegradability OECD 301C ≥ 70%

Insulating oil 500 is used that does not contain poly chlorinated biphenyl (PCB) other than the test standard of Table 1.

As shown in Table 2, the insulating oil 500 used in the embodiment of the present invention has a flow point of -22.5 degrees, a flash point of 314 degrees, and a kinematic viscosity of 34.5 (mm ^ 2 / s) and a degree of 100 degrees. It can be 8.880. In addition, the computational value was less than 0.4, the dielectric breakdown voltage was 83.4, the relative dielectric constant was 2.91, and the biodegradability was 99%.

division Insulating oil according to an embodiment of the present invention Pour point (℃) -22.5 Flash point (℃) 314 Kinematic viscosity 40 (℃)
100 (℃) 34.59
8.880 Computer Value (mg KOH / g) Less than 0.1 Breakdown voltage (kV / 2.5 mm) 83.4 Dielectric constant (60Hz, 80 ℃) 2.91 Biodegradability (%) 99

As shown in Table 2, the insulating oil 500 according to the embodiment of the present invention has a high flash point, has excellent flame retardancy, biodegradability of 99%, and is environmentally friendly. have.

In addition, the insulating oil 500 is slower than the mineral oil deterioration rate in the insulating paper used for the interlayer insulation of the winding. Thus, the life of the transformer can be extended.

The iron core 300 may use a silicon steel sheet having a thickness of 0.22 to 0.27 mm. Here, the iron core 300 may use a steel sheet in which 2 to 4 parts by weight of silicon is mixed with 100 parts by weight of iron. The iron core 300 has a density of 7.65 (g / cm ³ ), and the saturation magnetic flux density is 1.88 (Tesla) or more. Iron core 300 according to an embodiment of the present invention can be increased if the iron loss is 0.85 (W / kg) thickness is 0.27 or more. Also, if the thickness of the iron core is smaller than 0.23 mm, the noise may increase.

The columnar transformer according to the embodiment of the present invention may reduce the weight of the transformer by adjusting the thickness, density, and silicon content of the iron core 300, and also prevents an increase in iron loss and may reduce noise.

Iron core according to the present invention can be used a fine-grained silicon steel sheet. Magnetic domain micronized silicon steel sheet is the same as the above-described silicon steel sheet and the silicon mixing ratio, density, saturation magnetic flux density, iron loss, etc., but is a steel sheet produced by miniaturizing the magnetic domain on the silicon steel sheet by a laser method. Magnetically refined silicon steel sheet may have an iron loss of 0.8 to 0.95 (W / kg) depending on the thickness. If the thickness increases, the iron loss increases, so use a steel sheet within 0.27mm, or use a steel plate over 0.22mm to reduce noise.

The iron core 300 may use a structure as shown in FIG. 3. At this time, the winding is wound around the core or pillars of both sides.

Primary voltage of the primary winding unit 100 is applied. Primary winding unit 100 is a copper wire 101 is used is wound in a circular or elliptical.

The secondary winding 150 may be wound around the iron core 300 and may be wound inside the primary winding 10. The secondary winding unit 150 may be wound to be bent along the edge of the iron core 300 using the aluminum wire 151. The secondary winding unit 150 may be formed in a cross section of a quadrangular shape. Since the secondary winding unit 150 uses aluminum, the conductivity is lower than that of the copper wire, but the specific gravity is low, the price is low, and thus the weight of the column transformer can be reduced, and the manufacturing cost can be reduced. For example, since the secondary winding 150 is made of aluminum, the volume can be increased by using an aluminum square wire having a cross-sectional area of about 1.6 times that of copper, but the weight can be reduced to about 50%.

In addition, the secondary winding unit 150 may maintain chemical stability since the deterioration due to heat, chemical reaction with the conductor and the insulator due to the loss of the insulating oil 500 is lower than that of the copper wire. Accordingly, the life of the transformer can be increased.

Double coating AI-EIW may be used to prevent cracks generated in the coating film during rolling to cover the aluminum wires of the secondary winding part 150.

On the other hand, although not shown in Figure 1 and 2, it may further include a fastener. Fasteners are installed on the upper end of the winding portion (100, 150) may be fixed to the iron core (300). At this time, the fastener may be formed by penetrating so that the insulating oil 500 is supplied to the center in parallel with the winding. The region penetrating the fastener may be provided with a number other than the center as needed.

The primary side bushing 700 is connected with the primary winding 100. The secondary side bushing 800 is connected to the secondary winding 150.

The primary side bushing 700 and the secondary side bushing 800 may use a polymer bushing or a polymer composite bushing.

The polymer bushing or polymer composite bushing used for the primary side bushing 700 and the secondary side bushing 800 is formed of a silicone sheath. The primary side bushing 700 and the secondary side bushing 800 are excellent in water repellency by the silicon sheath, and have low surface damage, thereby suppressing an increase in leakage current, and thus have excellent insulation strength. In addition, the primary side bushing and the secondary side bushing 800 may be tin-plated on the metal surface to prevent whitening of the bracket, thereby preventing corrosion by salt damage.

The primary side bushing 700 and the secondary side bushing 800 may be lighter in weight than the magnetic bushing to reduce the weight of the transformer.

The tap switching unit 400 may adjust the magnitude of the voltage supplied to the customer by adjusting the winding ratio of the secondary winding unit 150. The tap switching unit 400 may be formed outside the transformer enclosure 600. The tap switching unit 400 may use a double O-ring rotary seal method, but is not limited thereto.

As the dial plate and the outer plastic of the tap-changing unit 400, polycarbonate having excellent impact resistance, heat resistance, cold resistance, weather resistance, and excellent electrical characteristics and dimensional stability may be used.

The external metal of the tap-changing unit 400 may use stainless steel, and the internal plastic may use PC / PBT glass (30%) having excellent chemical resistance, heat resistance, friction wear resistance, and excellent electrical characteristics.

The tap switching unit 400 according to the embodiment of the present invention may be formed outside to increase the convenience of operation and increase visibility.

On the other hand, as shown in Figure 1 may further include a protective cap 420 for protecting the tap-changing unit 400.

The protective cap 420 may be formed to protrude from the transformer enclosure 600 on the tab switching unit 400. The protective cap 420 may be formed in an arc shape or a straight shape.

On the other hand, the present invention may further include a heat dissipation means 900 for heat dissipation of the transformer enclosure 600.

The heat dissipation means 900 may be a plurality of sheets attached to the transformer enclosure 600. The heat dissipation means 900 may be attached to the transformer enclosure 600 or a plurality of fins in addition to the plurality of sheets, or a pipe shape may be attached to the transformer enclosure 600.

The heat dissipation means 900 may be attached to the transformer enclosure 600 by combining a plurality of wavy sheets. In this case, the weight of the transformer can be reduced and heat dissipation can be enhanced.

In addition, according to an embodiment of the present invention, it may further include a lifting ring 950 for carrying the columnar transformer. The impression ring 950 may be attached to both sides of the transformer enclosure 600 to match the center of gravity of the transformer. At this time, the lifting ring 950 may be manufactured in the form of a ring or a jaw so that a rope or the like for carrying or installation is sufficiently caught. The tensile strength of the pulling ring 950 can be designed to be at least five times the total weight of the transformer.

According to an embodiment of the present invention, although not shown in the drawings, it may further include a pressure release device. The pressure relief device can automatically reduce the discharge force when the pressure inside the transformer rises and automatically return when the pressure drop is below a certain pressure. Pressure relief device may be installed on the half-side of the tap-changing unit 400. The pressure relief device can use a pressure relief valve or the like.

Figure 4 is a perspective view for explaining the insulating paper of the primary winding portion and the secondary winding of the present invention, Figure 5 is a cross-sectional view showing a cross section of the primary and secondary windings shown in FIG.

4 and 5, the columnar transformer according to an exemplary embodiment of the present invention may include a first insulating layer 110 formed in the primary winding part 100 and a second insulating layer formed in the secondary winding part 150 ( 160 and a third insulating layer 200 insulating between the primary winding part 100 and the secondary winding part.

The first insulating layer 110 may include a first insulating paper 111 and a second insulating paper 112.

The first insulating paper 111 may include a type H insulating paper having a maximum allowable temperature of 180 degrees. The first insulating paper 111 may be formed at a side in direct contact with the copper wire 101 of the primary winding part 100. The first insulating paper 111 has a high maximum allowable temperature, thereby preventing the occurrence of insulation breakdown caused by the heat generation of the primary winding part 100.

The second insulating paper 112 may be formed between the first insulating paper 111 that does not contact the copper wire 101. The first insulating paper 111 may be an A * type insulating paper having a maximum allowable temperature of 120 degrees, and may include an insulating paper having a lower maximum allowable temperature than a type H insulating paper.

The second insulating layer 160 may include a third insulating paper 161 and a fourth insulating paper 162.

The third insulating paper 161 may include a Class H insulating paper having a maximum allowable temperature of 180 degrees. The third insulating paper 161 may be formed at a side in direct contact with the copper wire 101 of the secondary winding part 150. Since the third insulating paper 161 has the highest allowable temperature, insulation breakdown caused by the heat generation of the secondary winding 150 may be prevented.

The fourth insulating paper 162 may be formed between the third insulating paper 161 which does not contact the copper wire 101. The fourth insulating paper 162 may be an A * type insulating paper having a maximum allowable temperature of 120 degrees, and may include insulating paper having a lower maximum allowable temperature than the third insulating paper 161.

The A * type insulating paper may include a heat resistant paper. At this time, the heat-resistant paper is epoxy coated and the cable and the insulating paper is stably bonded by the epoxy resin of the double-sided diamond pattern can be improved mechanical strength.

Although the second insulating paper 112 and the fourth insulating paper 162 have been described using an A * type insulating paper as an example, the present invention is not limited thereto, and the second insulating paper 112 and the fourth insulating paper 162 may be the highest. Class A insulating paper with a temperature of 105 degrees may be used.

As described above, two or more kinds of insulating paper may be formed in the first insulating layer 110 and the second insulating layer 160 to improve the breakdown voltage characteristic and the heat resistance characteristic.

The third insulating layer 200 is formed between the primary winding part 100 and the secondary winding part 150 to insulate the two winding parts 100 and 150.

6 is a view showing the upper surface of the columnar transformer shown in Figure 1, Figure 7 is a side view showing the cover of the transformer enclosure shown in FIG.

6 and 7, the cover of the transformer enclosure will be described in detail.

6 and 7, the columnar transformer according to an exemplary embodiment of the present invention may include a cover 650 hingedly coupled to a cylindrical sidewall 610.

The cover 650 may include a recess 660. The recess 660 may reinforce the strength of the cover 650. A plurality of recesses 660 may be formed to extend in the end direction of the cover 650 based on the center thereof.

The cover 650 may be formed in a conical shape so that the cover 650 is directed toward the center from the surface abuts the side wall on the transformer enclosure side wall. That is, the cover may be formed to be inclined about 15 degrees from the center to the outward direction. The cover 650 formed to be inclined may prevent moisture from penetrating and prevent landing of algae. Here, the inclination angle is not limited to 15 degrees, and may be freely changed according to design.

The cover 650 may be coupled to the side wall of the transformer enclosure by a band tightening method. In this case, the cover 650 may further include a gasket to maintain airtightness.

As described above, the cover of the columnar transformer according to the embodiment of the present invention may be formed in a conical shape so that the internal capacity of the transformer enclosure may be increased.

8 to 11 are plan views illustrating lower surfaces of a transformer enclosure according to an exemplary embodiment of the present invention.

8 to 11, the bottom surface of the transformer enclosure may include support means 910, 920 protruding outward.

Specifically, the support means 910 may be formed in a form in which a plurality of support pieces are divided, as shown in FIGS. 8 and 9. At this time, the support means 910 may be arranged a plurality of support pieces of the arc shape as shown in FIG. In addition, as shown in FIG. 9, the support means 910 may be provided with a plurality of support pieces having a “a” shape. 8 and 9 illustrate that four support pieces are disposed, but the number of support pieces is not limited thereto and may be two, three, or four or more.

As described above, the support means 910 having the divided support pieces is excellent in ventilation of the lower part of the transformer, and the appearance is beautiful. In addition, the support means 910 is simple in shape can reduce the material cost.

On the other hand, the support means 920 may be formed in a polygon. As shown in FIG. 10, the support means 920 may be square. In addition, the support means 920 may be formed in a hexagonal shape.

The support means 920 shown in FIGS. 10 and 11 are easy to store on a sleeper or pallet and are advantageous for maintaining the transformer level.

The support means 910 and 920 illustrated in FIGS. 8 to 11 may prevent corrosion due to breakage or surface coating peeling off due to rolling during movement or installation of the columnar transformer.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims And changes may be made without departing from the spirit and scope of the invention.

100: primary winding
101: copper wire
110: first insulating layer
111: first insulating paper
112: second insulating paper
150: secondary winding
151: aluminum wire
160: second insulating layer
161: third insulating paper
162: fourth insulating paper
200: third insulating layer
300: iron core
400: tap-changing part
420: protective cap
500: insulating oil
600: transformer enclosure
650: cover
660: recess
700: primary bushing
800: secondary bushing
900: heat dissipation means
910, 920: support means
950: raise collar

Claims (16)

Transformer enclosure;
An iron core formed of silicon steel sheet for forming porcelain in the transformer enclosure;
A primary winding wound around the iron core in a copper wire;
A secondary winding unit wound around the iron core with an aluminum wire;
A first insulating layer formed between the primary winding and the secondary winding;
A second insulating layer for inter-winding insulation of the primary winding;
A third insulating layer for inter-winding insulation of the secondary winding part; And
It includes vegetable insulating oil for the insulation of the transformer enclosure and the iron core, the primary winding and the secondary winding,
The thickness of the silicon steel sheet is 0.23 to 0.27mm, the density is 7.65 (g / cm ³ ), the silicon content of the silicon steel sheet is characterized in that the column-type transformer, characterized in that 2 to 4 parts by weight based on iron.
The method of claim 1,
The iron core
Columnar transformer, characterized in that 3 parts by weight of silicon based on iron.
The method of claim 1,
The primary winding is wound in the copper wire layered,
And the first insulating layer further comprises a first insulating paper for directly contacting and insulating the copper wire between the layers of the copper wire and a second insulating paper for non-contacting insulation with the copper wire.
The method of claim 3, wherein
And the first insulating paper is an insulating paper having a higher maximum allowable temperature than the second insulating paper.
The method of claim 1,
The secondary winding part is wound around the aluminum line in a layer,
And the second insulating layer further comprises a third insulating paper for directly contacting and insulating the aluminum wire between the layers of the aluminum wire and a fourth insulating paper for non-contact insulation with the aluminum wire.
The method of claim 5, wherein
And said third insulating paper is an insulating paper having a higher maximum allowable temperature than said fourth insulating paper.
The method of claim 1,
The transformer enclosure
Cylindrical sidewalls;
A lower surface formed under the sidewall; And
And a cover formed on the top of the side wall in a conical shape so as to face toward the center from the side facing the side wall and hingedly coupled to the side wall.
The method of claim 7, wherein
The cover is
And at least one recess formed concavely in an inward direction of the transformer enclosure.
The method of claim 7, wherein
The lower surface is
A column transformer which protrudes outward of the transformer enclosure, further comprising a support means formed in a polygon.
The method of claim 7, wherein
The lower surface is
A pillar transformer which protrudes outwardly of the transformer enclosure, further comprising support means in which a plurality of support pieces are divided.
The method of claim 7, wherein
And heat dissipation means in contact with said side wall to dissipate said transformer enclosure.
The method of claim 1,
A high pressure bushing connected to the primary winding; And
And a low pressure bushing connected to the secondary winding.
The method of claim 1,
Further comprising a tap switching unit for adjusting the winding ratio of the secondary winding,
The tap-changing portion is a column transformer, characterized in that formed on the outside of the transformer enclosure.
The method of claim 13,
And a protection cap protruding outward from the transformer enclosure to protect the tap-changing portion.
The method of claim 1,
And a pressure relief device on the opposite side of the tap-changer to reduce the pressure when the pressure rises inside the transformer enclosure and to return when the pressure is lowered below a predetermined pressure.
The method of claim 1,
And a pair of pulling rings located on the center of gravity of the transformer outside the transformer enclosure.

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