The present invention relates to a displacement-controlled earthquake-resistant transformer employing a friction damper, including: a device body; an upper frame disposed in an upper portion of the device body to fix the device body; a lower frame disposed in a lower portion of the device body to fix the device body to a base while supporting the device body; and a friction damper unit disposed between the device body and the base to interwork with the device body and the base, and configured to buffer a vibration transmitted to the device body through the base fixed to a ground surface. According to the present invention, seismic energy is absorbed by using a frictional force of a damper in the event of an earthquake, so that damage that may be caused to the transformer by an earthquake shock is prevented.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a displacement-controlled earthquake-resistant transformer employing a friction damper, and more particularly, to an earthquake-resistant transformer in which a friction damper structure is applied to the transformer to improve earthquake-resistant performance.

2. Description of the Related Art

A transformer is a device including an iron core and a winding wire to convert a reception voltage or a distribution voltage into a voltage suitable for a load through electromagnetic induction, which is one of the most important devices in electric power transformation facilities.

A transformer in which a transformer body is immersed in insulating oil is referred to as an oil-immersed transformer, which is generally used due to a low price, strong dielectric strength, and a low maintenance cost thereof. In addition, a transformer in which a transformer body is insulated and molded with an epoxy resin is referred to as a molded transformer, which has a small size and a low risk of fire, but has vulnerability to an impulse voltage.

Since such transformers are installed in most electric power reception/transformation facilities, an operation of the transformer has to always be performed in a stable state for stable supply an electric power. In particular, considering that an earthquake having a magnitude of 5.8 has occurred at an epicenter of Gyeongju in 2016, Korea is also not a safe area from earthquakes, so that a device for protecting the transformer from a vibration of an earthquake is requisitely necessary to enable a control so that life and property may be maintained in an emergency situation.

In addition, since the transformers frequently have breakdowns and explosion accidents due to an impact and the like caused by a vibration, special attention and technology are required so that an impact transmitted to the transformer may be minimized to prevent breakdowns and explosions of the transformer caused by the vibration in the event of an earthquake.

In particular, when a transformer breaks down or explodes in the event of an earthquake, a protective relay of a power plant or a substation may detect the breakdown or explosion of the transformer so that a wide area may be blacked out, which may cause enormous damage to the life and property, so that there is an urgent need for developing technology for minimizing damage to the transformer caused by the earthquake.

Seismic waves include P-waves and S-waves that pass through an inside of the Earth, and surface waves (Rayleigh waves and Love waves) that travel along a ground surface of the Earth. In general, the waves are observed in an order of the P-waves, the S-waves, and the surface waves. The P-waves do not cause much damage to structures, whereas the S-waves and the surface waves do great damage to the structures. The P-wave is referred to as a push-wave, which is a longitudinal wave in which a propagation direction and a vibration direction are parallel to each other, and the S-wave is referred to as a shake-wave, which is a transverse wave in which the propagation direction and the vibration direction are perpendicular to each other. The surface wave propagating along the ground surface is referred to as a long-wave due to a large vibration and a long wavelength thereof, and causes the greatest damage such as landslides and building collapses among the seismic waves because the surface wave significantly shakes the ground surface. In particular, among the surface waves, the Rayleigh waves are observed later than the Love waves and have the strongest destructive power.

The surface waves may adversely affect a bus bar and peripheral devices connected to the transformer or cause a major accident, leading to departure of numerous devices, so that serious damage such as shutdown to various electric power reception/distribution devices including transformers may be secondarily caused by long-period surface waves.

However, in most cases, a conventional buffer device for an earthquake focuses on mitigating short-period vibrations, so that a separate device for attenuating long-period vibration waves is required when the conventional buffer device is applied. Therefore, a significant increase in a cost is unavoidable, and there is a concern that operations of a short-period vibration buffer device and a long-period vibration device may conflict with each other.

Therefore, there is an urgent need for technology capable of effectively attenuating short-period vibrations while attenuating long-period vibrations for a sensitive electric power reception/distribution device such as a transformer.

SUMMARY OF THE INVENTION

The present invention has been devised to solve the problems of the related art described above, and an object of the present invention is to provide an earthquake-resistant transformer in which a friction damper structure is applied to the transformer to improve earthquake-resistant performance.

To achieve the objects described above, according to the present invention, there is provided a displacement-controlled earthquake-resistant transformer employing a friction damper, the displacement-controlled earthquake-resistant transformer including: a device body; an upper frame disposed in an upper portion of the device body to fix the device body; a lower frame disposed in a lower portion of the device body to fix the device body to a base while supporting the device body; and a friction damper unit disposed between the device body and the base to interwork with the device body and the base, and configured to buffer a vibration transmitted to the device body through the base fixed to a ground surface.

In addition, according to an embodiment of the present invention, the friction damper unit may include: a damper base disposed on the ground surface to support a lower end portion of the lower frame; a support frame connected to both side portions of the upper frame; a first damper bar fixed to an upper portion of the damper base by a damper bracket; and a second damper bar having a lower portion connected to the first damper bar and an upper portion connected to the support frame.

In addition, according to an embodiment of the present invention, the friction damper unit may further include a friction pad disposed between the first damper bar and the second damper bar and making frictional contact with the first damper bar and the second damper bar to buffer the vibration, and the friction pad may include a material having relatively high elasticity or relatively high ductility as compared with a material of each of the first and second damper bars.

In addition, according to an embodiment of the present invention, a first center hole having a circular shape and formed on a center side of the first damper bar, a pad center hole having a circular shape and formed on a center side of the friction pad, and a second center hole having a circular shape and formed on a center side of the second damper bar may be connected to each other through a center bolt.

In addition, according to an embodiment of the present invention, a plurality of first side holes having a circular shape and formed on an outer side of the first damper bar in a circumferential direction, a plurality of pad side holes having an elliptical shape and formed on an outer side of the friction pad in a circumferential direction, and a plurality of second side holes having an elliptical shape and formed on an outer side of the second damper bar in a circumferential direction may be connected to each other through a plurality of side bolts to mitigate a displacement of the device body in a Y-axis direction.

In addition, according to an embodiment of the present invention, a plurality of first middle holes having a circular shape and formed between the first center hole and the first side hole on the first damper bar in the circumferential direction, a plurality of pad middle holes having an elliptical shape and formed between the pad center hole and the pad side hole on the friction pad in the circumferential direction, and a plurality of second middle holes having an elliptical shape and formed between the second center hole and the second side hole on the second damper bar in the circumferential direction may be connected to each other through middle bolts to mitigate the displacement of the device body in the Y-axis direction.

According to the present invention, seismic energy may be absorbed by using a frictional force of a damper in the event of an earthquake, so that damage that may be caused to the transformer by an earthquake shock can be prevented.

In addition, the present invention has a simple structure and does not occupy a wide space, installation can be easily performed in existing transformer facilities, and maintenance and repair can be easily performed.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a displacement-controlled earthquake-resistant transformer employing a friction damper according to exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring toFIGS.1and2, according to the present invention, an earthquake-resistant transformer10may include a device body20, a first spacer31, a second spacer33, an upper frame41, a lower frame43, and a friction damper unit100.

The device body20may constitute an exterior of a molded transformer, and may be implemented in a cylindrical shape. Openings (not shown) may be formed in upper and lower center sides of the device body20.

Basically, the molded transformer may include an iron core, a low-voltage coil, and a high-voltage coil.

First, the iron core may pass through a center portion of the device body20through openings formed at a top and a bottom of the device body20.

In addition, the low-voltage coil may be arranged inside the device body20in a circumferential direction. The low-voltage coil may surround an outer periphery of the iron core while being spaced apart from the iron core by a predetermined distance.

In addition, the high-voltage coil may be arranged inside the device body20in the circumferential direction. In this case, the high-voltage coil may surround an outer periphery of the low-voltage coil while being spaced apart from the low-voltage coil by a predetermined distance.

A plurality of first spacers31may be disposed in an upper portion of the device body20. A plurality of second spacers33may be disposed in a lower portion of the device body20. In this case, the first spacer31and the second spacer33may be disposed at corresponding positions of the upper and lower portions of the device body, respectively.

The upper frame41may be a C-shaped frame disposed in an upper portion of the first spacer31to support the device body20. In addition, the lower frame43may be a C-shaped frame disposed in a lower portion of the second spacer33to fix the device body20to a base45while supporting the device body20. However, shapes of the upper frame41and the lower frame43are not necessarily limited to the above configuration.

The iron core may protrude upward and downward from the device body20to traverse a longitudinal direction of the upper frame41and the lower frame43.

In addition, a pair of upper frames41and a pair of lower frames43may be arranged with respect to the iron core, and fastened to each other with connection bolts47to fix and support the device body20, respectively.

Meanwhile, the friction damper unit100may be disposed between the device body20and the base45to interwork with the device body20and the base45, and may perform a function of buffering a vibration transmitted to the device body20through the base45fixed to a ground surface.

The friction damper unit100may include a damper base180, a support frame150, a first damper bar110, a second damper bar130, and a friction pad120.

The damper base180may be disposed on the ground surface to support a lower end portion of the lower frame43.

The support frame150may be connected to both side portions of the upper frame41. Referring toFIGS.1and3, the support frame150may have a C-shape, and a top and a bottom of the support frame150may be fastened and coupled to the upper frame41through bolts151. In addition, a side surface of the support frame150may be connected to an upper portion of the second damper bar130through coupling of a hinge pin170and a counter nut171.

The support frame150may include a metal material with excellent rigidity, such as iron, or a material such as reinforced ceramic.

The first damper bar110may be fixed to an upper portion of the damper base180by fastening a bolt to a damper bracket160.

Referring toFIG.4, the first damper bar110may include a first center hole111, a first middle hole113, a first side hole115, and a bracket hole119.

The first center hole111may be formed on a center side of the first damper bar110, and may have a circular shape. The first side hole115may be formed on an outer side of the first damper bar110, and may have a circular shape. A plurality of first middle holes113may be formed between the first center hole111and the first side hole115in a circumferential direction, and may have a circular shape.

The first damper bar110may be fixed to the upper portion of the damper base180by fastening a bolt to the bracket hole119.

The second damper bar130may have a lower portion connected to the first damper bar110, and an upper portion connected to the support frame150.

Referring toFIG.6, the second damper bar130may include a second center hole131, a second middle hole133, a second side hole135, and an upper hole139.

The second center hole131may be formed on a center side of the second damper bar130, and may have a circular shape. A plurality of second side holes135may be formed on an outer side of the second damper bar130, and may have an elliptical shape. A plurality of second middle holes133may be formed between the second center hole131and the second side hole135in a circumferential direction, and may have an elliptical shape.

Side portions of the second damper bar130and the support frame150may be connected to each other by fastening the hinge pin170to the counter nut171through the upper hole139.

Each of the first and second damper bars may include a metal material with excellent rigidity, such as iron, or a material such as reinforced ceramic.

The friction pad120may be disposed between the first damper bar110and the second damper bar130, and may make frictional contact with the first damper bar110and the second damper bar130to buffer the vibration. The friction pad120may include an elastic material such as rubber or a metal material with high ductility such as lead or copper.

In other words, the friction pad120may include a material having relatively high elasticity or a material having relatively high ductility as compared to a material of each of the first and second damper bars110and130. This is because the friction pad120has to make frictional contact with the first and second damper bars110and130to absorb the vibration.

While a material characteristic of the friction pad120is long-term use, a user may replace only the friction pad120in a case of damage or breakage caused by an actual earthquake, so that a cost for maintenance and repair may be reduced, and maintenance and repair operations may become easier.

Referring toFIG.5, the friction pad120may include a pad center hole121, a pad middle hole123, and a pad side hole125.

The pad center hole121may be formed on a center side of the friction pad120, and may have a circular shape. A plurality of pad side holes125may be formed on an outer side of the friction pad120, and may have an elliptical shape. A plurality of pad middle holes123may be formed between the pad center hole121and the pad side hole125on the friction pad120in a circumferential direction, and may have an elliptical shape.

In this case,FIGS.1and2may show a state in which the friction pad120is disposed between the first and second damper bars110and130on the damper base180.

Vibrations and shaking caused by the earthquake and transmitted from the ground surface to the base45, the lower frame43, the device body20, and the upper frame41may be reduced by a frictional resistance using surface contact on surfaces of the friction pad120disposed on the upper portion of the damper base180that face the first and second damper bars110and130, respectively. As a result, the vibrations and shaking transmitted upward from the lower frame43to the device body20and the upper frame41may be buffered in an entire portion of the mold transformer.

Meanwhile,FIG.7is an exploded perspective view showing the friction pad120between the first and second damper bars110and130.

The first center hole111having a circular shape and formed on the center side of the first damper bar110, the pad center hole121having a circular shape and formed on the center side of the friction pad120, and the second center hole131having a circular shape and formed on the center side of the second damper bar130may be coupled and connected to each other through by a center bolt141and a nut147.

The first side holes115having a circular shape and formed on the outer side of the first damper bar110in the circumferential direction, the pad side holes125having an elliptical shape and formed on the outer side of the friction pad120in the circumferential direction, and the second side holes135having an elliptical shape and formed on the outer side of the second damper bar130in the circumferential direction may be coupled and connected to each other by a plurality of side bolts145and nuts147.

The first middle holes113having a circular shape and formed between the first center hole111and the first side hole115on the first damper bar110in the circumferential direction, the pad middle holes123having an elliptical shape and formed between the pad center hole121and the pad side holes125on the friction pad120in the circumferential direction, and the second middle holes133having an elliptical shape and formed between the second center hole131and the second side hole135on the second damper bar130in the circumferential direction may be coupled and connected to each other by middle bolts143and nuts147.

In this case, each of the pad middle hole123, the pad side hole125, the second middle hole133, and the second side hole135may have an elliptical shape, the pad middle holes123and the pad side holes125may be disposed in the friction pad120in the circumferential direction, and the second middle holes133and the second side holes135may be disposed in the second damper bar130in the circumferential direction.

Since the middle bolt143and the side bolt145may move in the circumferential direction within the holes having an elliptical shape, a displacement of the device body20in a Y-axis direction may be mitigated.

Since the center bolt141is coupled to the hole having a circular shape, the center bolt141may function as a center axis.

In addition, since the middle bolt143and the side bolt145are coupled to the holes having an elliptical shape, the middle bolt143and the side bolt145may slightly move in the circumferential direction about the center bolt141.

In this case, since the first and second damper bars110and130make surface contact with the friction pad120, when the middle bolt143and the side bolt145move within the holes having an elliptical shape, a frictional resistance may be generated to suppress the movement. During the above action, the displacement of the device body20in the Y-axis direction may be mitigated.

According to the present invention, seismic energy may be absorbed by using a frictional force of a damper described above, so that damage that may be caused to the transformer by the vibrations and shaking in the event of an earthquake may be prevented.

Meanwhile,FIGS.8to13show experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention. An experimental condition was set as an ICC-ES AC156 standard, which is an acceptable standard for seismic certification, and a magnitude of an earthquake was 6.0 to 7.0.

FIG.8is experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention with respect to a displacement in a Y-axis direction according to a time when 100% of a seismic wave conforming to an AC156 standard is applied.

According to the experimental data, B denotes a displacement of a conventional molded transformer in a Y-axis direction, and R denotes a displacement of an earthquake-resistant transformer according to the present invention in a Y-axis direction. In this case, a displacement value is based on an uppermost portion of the transformer.

According to displacement values of the experimental data, it was found that a displacement value in the Y-axis direction is reduced in the earthquake-resistant transformer R according to the present invention as compared with the conventional molded transformer B under the above experimental conditions, which corresponds to a decrease of approximately 68%.

FIG.9is experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention with respect to a displacement in the Y-axis direction according to a time when 200% of the seismic wave conforming to the AC156 standard is applied.

According to the experimental data, B denotes a displacement of a conventional molded transformer in a Y-axis direction, and R denotes a displacement of an earthquake-resistant transformer according to the present invention in a Y-axis direction. In this case, a displacement value is based on an uppermost portion of the transformer.

According to displacement values of the experimental data, it was found that a displacement value in the Y-axis direction is reduced in the earthquake-resistant transformer R according to the present invention as compared with the conventional molded transformer B under the above experimental conditions, which corresponds to a decrease of approximately 68%.

It was found throughFIG.9that the earthquake-resistant transformer according to the present invention satisfies a unidirectional displacement width of 75 mm (dashed line L), which is a determination condition of an earthquake-resistant test scheme (earthquake-resistant test scheme for broadcasting and communication facilities 2015) stipulated in standards of the National Radio Research Institute in Korea.

Exact displacement values of the experimental data are shown in Table 1 below.

FIG.10is experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention with respect to a response acceleration in an X-axis direction according to a time when 100% of the seismic wave conforming to the AC156 standard is applied.

According to the experimental data, B denotes a response acceleration of a conventional molded transformer in an X-axis direction, and R denotes a response acceleration of an earthquake-resistant transformer according to the present invention in an X-axis direction. In this case, a displacement value is based on an uppermost portion of the transformer.

According to response acceleration values of the experimental data, it was found that a response acceleration value in the X-axis direction is reduced in the earthquake-resistant transformer R according to the present invention as compared with the conventional molded transformer B under the above experimental conditions, which corresponds to a decrease of approximately 28%.

FIG.11is experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention with respect to a response acceleration in the Y-axis direction according to a time when 100% of the seismic wave conforming to the AC156 standard is applied.

According to the experimental data, B denotes a response acceleration of a conventional molded transformer in a Y-axis direction, and R denotes a response acceleration of an earthquake-resistant transformer according to the present invention in a Y-axis direction. In this case, a displacement value is based on an uppermost portion of the transformer.

According to response acceleration values of the experimental data, it was found that a response acceleration value in the Y-axis direction is reduced in the earthquake-resistant transformer R according to the present invention as compared with the conventional molded transformer B under the above experimental conditions, which corresponds to a decrease of approximately 32%.

FIG.12is experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention with respect to a response acceleration in the X-axis direction according to a time when 200% of the seismic wave conforming to the AC156 standard is applied.

According to the experimental data, B denotes a response acceleration of a conventional molded transformer in an X-axis direction, and R denotes a response acceleration of an earthquake-resistant transformer according to the present invention in an X-axis direction. In this case, a displacement value is based on an uppermost portion of the transformer.

According to response acceleration values of the experimental data, it was found that a response acceleration value in the X-axis direction is reduced in the earthquake-resistant transformer R according to the present invention as compared with the conventional molded transformer B under the above experimental conditions, which corresponds to a decrease of approximately 30%.

FIG.13is experimental data showing earthquake-resistant performance of the earthquake-resistant transformer according to the present invention with respect to a response acceleration in the Y-axis direction according to a time when 200% of the seismic wave conforming to the AC156 standard is applied. According to the experimental data, B denotes a response acceleration of a conventional molded transformer in a Y-axis direction, and R denotes a response acceleration of an earthquake-resistant transformer according to the present invention in a Y-axis direction. In this case, a displacement value is based on an uppermost portion of the transformer.

In this case, it was found that there is no significant difference in the response acceleration values in the Y-axis direction between the conventional molded transformer B and the earthquake-resistant transformer R according to the present invention under the above experimental conditions.

Exact displacement values of the experimental data are shown in Table 2 below.

Accordingly, a specific embodiment of the displacement-controlled earthquake-resistant transformer employing the friction damper has been described.

Therefore, it will be easily understood by those of ordinary skill in the art that substitutes and changes can be made to the present invention in various forms without departing from the gist of the present invention as set forth in the appended claims.