KR20190069944A - Compression-limited rubber packing to prevent excessive tightening when assembling transformer bushing - Google Patents

Abstract

The present invention relates to a compression-limited circular ring for preventing excessive tightening when assembling a bushing in a transformer. More specifically, a device that converts a high voltage transmitted from a power plant to a low voltage (220V, etc.) at the customer side is called a transformer, and transformers are divided into columnar transformers installed on poles and ground transformers installed on the ground. A terminal connecting a high-voltage primary side and a low-voltage secondary side voltage is connected to an internal winding of the transformer through the bushing, wherein the bushing uses packing to seal insulating oil inside the transformer. By inserting a compression suppressing means for suppressing compression in the packing to adjust a compressive force, a leakage of the insulating oil due to insufficient pressure, aging of packing rubber caused by contact with the outside, and breakage or non-compression of the packing by excessive pressure can be prevented. In addition, one or more inner protrusions and upper and lower protrusions are formed on the outside of a contact surface with the bushing or a contact surface of the packing, such that the pressure of the bushing and the packing can be limited, and a more firm sealing effect can be achieved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a compression ring for preventing excessive tightening when assembling a bushing to a transformer,

The present invention relates to a compression-limited circular ring for preventing over-tightening of a bushing in a transformer. More specifically, the present invention relates to an apparatus for converting a voltage transmitted from a power plant into a high- The transformer is divided into a pole transformer installed on the pole and a ground transformer installed on the ground. The terminal connecting the primary side of the high voltage and the secondary voltage of the low voltage is connected to the transformer internal winding through the bushing, By using the packing to seal the insulating oil inside,

And the compression restricting ring is attached to the outside of the packing for the compression restraining means for stopping the compression, so that the leakage of the insulating oil due to insufficient pressure bonding, the aging of the packing rubber due to contact with the outside, It is possible to restrict the pressure of the bushing and the packing by forming one or more inner protrusions and up and down protrusions on the contact surface with the bushing or outside the contact surface of the packing And more particularly to a compression-limited circular ring that prevents excessive tightening when assembling a bushing to a transformer capable of achieving a more rigid sealing effect.

Generally, a device that converts the voltage that is transmitted from a power plant to a high voltage from a consumer to a low voltage (220V etc.) is called a transformer. The transformer can be classified into a pillar transformer installed on the pole and a ground transformer installed on the ground. In the ground transformer and pillar transformer, a terminal connecting the primary side of the high voltage and the secondary voltage of the low voltage is connected to the transformer internal winding through the bushing, which uses packing to seal the insulating oil inside the transformer.

For the most part, the interior of the transformer is filled with insulating oil to effectively isolate the high currents. This inductive transformer has a primary bushing for inputting electricity to the outside, a secondary bushing for connecting the output voltage of the transformer, The tap changer, various sensors and fuses are connected to the outside.

Parts such as a bushing connected to the outside seal the inside of the transformer by using packing to prevent the leakage of the insulating oil inside the transformer, thereby preventing the leakage of the insulating oil and preventing the inflow of contaminants such as external moisture.

In general, the packing material is made of materials such as natural rubber (NR), nitrile rubber (NBR), hydrogenated nitrile (HNBR), fluorine (FKM / FPM / Viton), acrylate rubber (ACM) The material must have abrasion resistance, heat resistance, resistance to external ozone (ozone resistance), and mechanical properties.

However, in the case of the packing used for the bushing as described above, when the bushing is assembled at the site where the transformer is assembled, the packing is damaged by excessive tightening, or the packing is loosened because the bushing is less tightened.

Most of the transformer accidents are caused by leakage of insulating oil from the transformer, and when the insulating oil is insufficient, the transformer explodes due to high current.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a bushing for a transformer which, when assembling a transformer bushing, It is important to properly tighten the packing, since cracks can easily occur when rubbing against air for a long period of time, and the tightening nut can easily be released if the packing compression is weak. The tightening ring of Teflon, which is designed to be assembled only at a constant compression ratio without considering the torque of the bushing's tightening nut, is attached around the existing packing to prevent excessive tightening of the packing. By allowing the ring to restrict the compression of the packing between the bushing and the outer wall of the transformer, the operator can check the tightness of the ring of compression limited ring of the Teflon so that the packing can be compressed by a certain amount of compression without considering the tightening torque. Wherein the compressive restricting ring is restrained from being compressed by 30% or more so as to prevent an excessive torque from being given to the worker to assemble the transformer. Ring.

As described above, by using the compression-restricting circular ring to prevent over-tightening when assembling the bushing in the transformer according to the present invention, the compression restraining means for stopping the compression can be achieved by binding the compression- It is possible to prevent oil leakage due to insufficient pressure and pressure contact, aging of the rubber due to contact with external ozone, and cracking of the packing due to excessive pressure and adhesion, or pressure shaft phenomenon.

In addition, by forming one or more inner projections and up and down projections on the contact surface with the bushing or outside the contact surface of the packing, the flow of the bushing and the insulator can be suppressed and a more robust sealing effect can be realized.

Generally, the packing uses a carbon black and a black rubber material. In the present invention, since the compression limited circular ring of Teflon having flexibility of white is used, the packing can be easily distinguished from the inner packing, It is possible to more clearly distinguish the degree of tightening and to prevent the packing from being excessively tightened, so that the life of the packing can be prolonged.

1 is a photograph showing a packing deterioration test according to a compression ratio of a transformer packing
2 is the front view of the packing for the transformer
Fig. 3 is a cross-sectional view of a compression surface when a planar packing is provided in a pillar-
Fig. 4 is a perspective view of the pillar for pillar transformer after compression (5 mm, 100 kVA)
Fig. 5 is a diagram showing a packing installation configuration in a secondary bushing for punching transformer
Figure 6 shows the compression section of the packing according to the enclosure diameter and the padding outer diameter when the packing is compressed
Fig. 7 is a perspective view of the transformer of the present invention,
Fig. 8 is a perspective view of a compression restricting ring for a pneumatic transformer of a compression-restricting circular ring, which prevents excessive tightening when the bushing is assembled to the transformer of the present invention
Figure 9 is a perspective view of a compression limited circular ring for a ground transformer of a compression limited circular ring that prevents excessive tightening during assembly of the bushing in the transformer of the present invention.
Fig. 10 is a perspective view of a compression-restricting circular ring for a pneumatic transformer of a compression-restricting circular ring, which prevents excessive tightening when the bushing is assembled to the transformer of the present invention.

The embodiments of the present invention may be modified in various ways, and the scope of the present invention should not be interpreted as being limited by the embodiments described below.

[0001] The present invention relates to a compression-limiting circular ring for preventing over-tightening of a bushing in a transformer, in which a pole transformer installed on a pole and a ground transformer installed on the ground are connected to a high- The bushing uses packing to seal the insulating oil inside the transformer,

And the compression restricting ring is attached to the outside of the packing for the compression restraining means for stopping the compression, so that the leakage of the insulating oil due to insufficient pressure bonding, the aging of the packing rubber due to contact with the outside, It is possible to restrict the pressure of the bushing and the packing by forming one or more inner protrusions and up and down protrusions on the contact surface with the bushing or outside the contact surface of the packing The present invention relates to a compression-limiting circular ring for preventing over-tightening when assembling a bushing to a transformer capable of achieving a more rigid sealing effect.

1 is a photograph showing a packing deterioration test according to a compression ratio of a transformer packing,

In order to confirm the problems caused when the packing is excessively squeezed, packing samples of three packing manufacturers for transformer (J yarn, S yarn, and Y yarn of the present invention) , Compressibility was 30% and 50%, respectively, and they were tested in an oven at 40 ° C and 120 ° C for 12 hours, respectively.

As shown in Table 1 and Fig. 1,

It can be seen from the deterioration test result of the packing sample in Table 1 that cracking occurs in most of the packing when the compression ratio is 50% or the restoring force of the packing after compression is lost.

Degradation test result according to compressibility of packing sample
Compressibility
Sample name
Packing material Test Methods Minus 40 ° C 12 hours 120 DEG C
12 hours


33% Invention
Manufacturers J Packing
Viton
normal
normal
Manufacturer Y packing Hydrogenated nitrile (HNBR)
normal After compression
Loss of resilience
Manufacturers S packing Hydrogenated nitrile (HNBR)
normal After compression
Loss of resilience

50% Invention
Manufacturers J Packing
Viton
normal
Cracking
Manufacturer Y packing Hydrogenated nitrile (HNBR)
normal After compression
Loss of resilience
Manufacturers S packing Hydrogenated nitrile (HNBR)
normal After compression
Loss of resilience

As shown in the test results, when the packing compression ratio is excessively high at the time of packing, it can be seen that the packing function is lost. When assembling the transformer, it is necessary to keep the compression ratio of the locker packing constant with the constant torque when the bushing, tap changer, and various sense packings are tightened, and leakage which occurs during most assembly process can be prevented. Even when using a torque wrench (tool) or various torque adjusting tools that can adjust the torque during assembly, it is not easy to get thick packings at a constant pressure and optimum sealing conditions.

□ Problems with common air tools

Generally, the packing used for the transformer is thicker and it needs to be cleaned with air impact or air ratchet. However, the amount of tightening depends on the condition of the assembler and the day. When the locking torque is 20 Nm in design, when the actual torque wrench is used to confirm the locking torque, it is actually 5 ~ 20 N.m or more.

□ Problems with Torque Limiter Impactor Air Tools

- Torque is set and the torque exceeds the set torque. Blocked torque may be used. Impact is sometimes used. Bolt fastened to the packing. Thickened to prevent corrosion. Depending on the thickness of the paint, even if the torque is constant, the packing is not squeezed. Lt; / RTI > The packing may not be compressed by a certain amount of compression, and may be weakly tightened or loosened.

In the case of a thick circular packing mainly used in a transformer, it is possible to assemble the sealing state at the best when locking while confirming the degree of compression of the packing rather than locking the torque of the fastening bolt. However, none of the existing tools can set the compression amount of the packing, not the torque,

FIG. 2 shows a front view of a transformer pack, wherein the bushing mounting portion of the ground-type transformer is flat and the bushing mounting portion is flattened, whereas the punching transformer is cylindrical and the bushing mounting portion is mostly round, And the outer compression ratio is different, most of the pillar transformer uses the same packing as the inner and outer sides of the transformer packing as shown in Fig. 2,

When a flat packing is installed in the pillar-shaped transformer of FIG. 3, as shown in the cross-sectional view of the compression surface, the inner side in the center portion has a low compression ratio of rubber and an excessively compressed outer side,

Most pillar transformers use a thickness of 5 mm,

As you can see in the table below, over 60% is compressed.

Compressed to 60% means that the 10mm packing is compressed to 4mm. The volume of the packing corresponding to 6mm is compressed. However, if it is bonded to the high temperature and the sharp part of the bushing, the crack will easily occur.

Fig. 4 shows a perspective view (5 mm, 100 kVA) after compressing the pillar for transformer,

When the compression ratio "C" is 30%

The difference x between the maximum compressed portion and the minimum compressed portion where the packing is compressed when the diameter of the transformer enclosure is Ct and the diameter of the packing is Do is represented by the packing mounting configuration in the secondary bushing for the pillar transformer of FIG. Can be derived using the trigonometric function as shown in the compression section of the packing according to the enclosure diameter and packing outer diameter,

The compression thickness of the part where the packing is most compressed becomes the maximum compression thickness minus x.

So to 'compress' to the minimum is calculated as follows.

Using the above formula, the thickness (ti ') at which the thickness of the packing is maximized by using the diameter (Dt) of the enclosure and the outer diameter (Do) (to ') and compression rates (Co, Ci) can be calculated as shown in the following table.

When the compression ratio Ci inside the packing is compressed to 30% as in the compression degree (minimum compression ratio: 30%) of the packing according to the capacity of the table transformer, the compressibility Co of the outside of the packing is 60% or more can see. If the compression rate is more than 60%, excessive stress is applied to the packing, which may easily crack if the temperature rises or the surface roughness is poor.

As can be seen from the compression degree (minimum compression ratio: 20%) of the packing according to the transformer capacity shown in the above Table 4, it can be seen that the outside compression ratio Co is 50% or more even when the inner compression ratio Ci of the packing is 20%.

NBR and HNBR packings are required to maintain compressibility of less than 30% because cracks tend to occur inside the packing when compressed by more than 50%.

FIG. 7 is a perspective view of a transformer according to an embodiment of the present invention,

In order to solve the above-mentioned problems, when the bushing 40 for a transformer is assembled, the packing 10 is compressed by tightening the bushing fastening nut. When the packing compression is excessively excessive, It is possible to easily crack when the rubbing is performed and the tightening nut can be easily loosened when the compression of the packing 10 is weak so that the flexibility of white which is configured to be assembled at a constant compression ratio without considering torque of the fastening nut of the bushing 40 (50) around the existing packing (10) to prevent the packing from being excessively tightened, and the Teflon compression-restricting ring (50) compresses the packing between the bushing and the outer wall of the transformer The worker can confirm the tight contact state of the compression limited circular ring 50 of the Teflon, and if the tightening torque is not taken into consideration, And a configuration that allows you to assemble by pressing,

8 is a perspective view of a compression-restricting circular ring for a pneumatic transformer of a compression-limiting circular ring for preventing over-tightening when assembling a bushing in a transformer of the present invention,

As in the configuration in which the compression-restricting ring 50 is mounted in assembling the bushing 40 to the transformer of FIG. 7,

The compression limited circular ring 50 for a pneumatic transformer of the present invention includes a compression display portion 53 having one or more inner projections 51 and a certain space on the contact surface with the bushing 40 or outside the contact surface of the packing 10 By forming the upper and lower protrusions 52, the compression-limiting circular ring 50 and the packing 10 are rotated and seated when they are tightened in the round-shaped wall of the pillar-type transformer,

And a compression limiting circular ring 50 for a pillar transformer which can be installed at an accurate position in the tightening process in which the bushing 40 and the packing 10 are installed.

The inner protrusion (51) functions to compress the circular ring (50) of the Teflon circular ring while compressing and to closely locate the magnetic seal with the packing (10)

The upper and lower protrusions 52 are used to compress the packing 10 while holding the packing 10 so that the compression restricting ring 50 of the Teflon and the packing 10 can be easily rotated to the center while assembling or moving, So that the assemblability is improved.

The compression display unit 53 having the predetermined space has two functions. When the space portion of the compression display unit 53 is closed, the display unit function indicating that the packing 10 is properly tightened, In addition, it has a function to mitigate the impact of the impact when compressing using the impact.

The compression limited circular ring 50 of the present invention uses a circular ring of white Teflon, while the packing 10 uses a black rubber material mostly using carbon black, So that it is possible to clearly distinguish the degree of tightness of the packing by the compression display portion 53.

9 is a perspective view of a compression-restricting circular ring for a ground-level transformer of a compression-restricting circular ring, which prevents over-tightening when the bushing is assembled to the transformer of the present invention,

The compression limited circular ring 50 for the ground transformer of the present invention is formed by forming the bushing 40 and the packing 10 by forming one or more inner projections 51 on the contact surface with the bushing 40 or outside the contact surface of the packing 10. [ 10), as well as a more restrictive sealing effect, as well as a compression-limiting circular ring 50 for a pneumatic transformer.

FIG. 10 is a perspective view showing an assembled perspective view of a compression-restricting circular ring for a pneumatic transformer of a compression-limiting circular ring for preventing over-tightening when assembling a bushing in a transformer of the present invention,

The inner surface of the packing 10 and the inner surface of the bushing 40 are covered with the inner protrusion 51 and the outer surface of the packing 10, And a compression limiting circular ring 50 for a pneumatic transformer having upper and lower protrusions 52 including a compression display portion 53 having a constant space is coupled.

Therefore, according to the present invention, the compressive restricting ring 50 for the pneumatic transformer of FIG. 8 and the compressive restricting ring 50 for the ground transformer of FIG. 9 use packing to seal the insulating oil in the transformer, By restricting the compressive force by binding the compression restricting ring to the outside of the packing for the compression suppressing means for stopping the compression of the packing rubber, the leakage of the insulating oil due to insufficient pressure bonding, the aging of the packing rubber due to contact with the outside, It is possible to restrict the pressure of the secondary bushing and the packing by forming one or more inner projections and up and down projections on the contact surface with the bushing or outside the contact surface of the packing And more particularly to a compression-limited circular ring that prevents excessive tightening when assembling a bushing to a transformer capable of achieving a more rigid sealing effect.

10 ; 패킹 20 : 절연체
30 : 변압기 외합 40 : 부싱
50 : 압축제한 원형링 51 : 내부 돌기
52 : 상하돌기 53 : 압축 표시부

10; Packing 20: Insulator
30: Transformer exceptions 40: Bushing
50: compression restricting ring 51: inner projection
52: Up and down projection 53: Compression display

Claims (5)

A packing (10) for preventing excessive tightening when assembling a bushing to a transformer,
The packing 10 forms a circular compression-restricting circular ring 50 on the contact surface with the bushing 40 or outside the contact surface of the packing 10,
Wherein the bushing (40) and the packing (10) can be pressurized and a more rigid sealing effect can be realized. The transformer according to claim 1, wherein the bushing (40)
The method according to claim 1,
The compression restricting ring 50 has upper and lower protrusions 52 including one or more inner protrusions 51 and a compression display portion 53 having a certain space on the contact surface with the bushing 40 or the contact surface of the packing 10 So that the compression restricting ring 50 and the packing 10 are rotated and seated when they are tightened at the rounded wall of the pillar transformer,
The bushing (40) and the packing (10) are installed at a precise position in a tightening process. The bushing (40) and the packing (10) Compression limited circular ring
The method according to claim 1,
The compression limited circular ring 50 may be formed by forming one or more inner protrusions 51 on the contact surface with the bushing 40 or outside the contact surface of the packing 10 so that the compression limited circular ring 50 and the packing 10 are connected to the pillar- The wall of the round shaped wall is rotated,
Wherein the bushing (40) and the packing (10) are installed at a precise position in the tightening process. The transformer according to claim 1, wherein the bushing (40) Compression limited circular ring
The method according to claim 1,
The compression display portion 53 of the compression restricting circular ring 50 is constituted by a display function for indicating that the packing 10 is properly tightened when the space portion is closed and a function for mitigating the impact shock when compressing using the impact A compression-limited circular ring that prevents over-tightening when assembling a bushing to a transformer.
The method according to claim 1,
Since the compression-limiting circular ring 50 uses a white ring of Teflon, it can be easily distinguished from the inner black packing 10, so that the compression display unit 53 can more clearly distinguish the tightness of the packing A compression-limited circular ring that prevents over-tightening when assembling a bushing to a transformer.

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