CN109346292B

CN109346292B - Workshop dry-type transformer cooling device

Info

Publication number: CN109346292B
Application number: CN201811565887.3A
Authority: CN
Inventors: 肖锐
Original assignee: Xiangshan Duipeng Electronic Technology Co ltd
Current assignee: Xiangtan Nuohe Electrical Equipment Co.,Ltd.
Priority date: 2018-12-20
Filing date: 2018-12-20
Publication date: 2020-05-05
Anticipated expiration: 2038-12-20
Also published as: CN109346292A

Abstract

The invention relates to the field of transformers, in particular to a workshop dry-type transformer cooling device; comprises a shell and a plurality of coil groups arranged in the shell; the coil group comprises a coil and a central pipeline; the coils are coaxially arranged and wound in a plurality of sections in the circumferential direction of the central pipeline; the adjacent two sections of the firing coils are separated by grid pads; the coil, the grid cushion and the central pipeline are cast into a whole by epoxy resin; the top end and the bottom end of the central pipeline extend out of the shell. By adopting the technical scheme of the invention, the problem of low heat dissipation speed of the coil in the prior art can be solved.

Description

Workshop dry-type transformer cooling device

Technical Field

The invention relates to the field of transformers, in particular to a workshop dry-type transformer cooling device.

Background

The transformer comprises a dry type transformer and an oil immersed transformer; compared with oil immersed transformers, the dry type transformer is superior to the oil immersed transformer in the aspects of environmental protection, fire prevention, flame retardation, impact resistance and the like, and is adopted in buildings and places with dense personnel at present, so that the dry type transformer is widely used in the places with dense personnel such as workshops.

In short, a dry transformer refers to a transformer in which the core and the winding are not immersed in insulating oil. The cooling method is classified into natural air cooling (AN) and forced air cooling (AF). Because workshop production equipment is many, and power consumption is big, leads to dry-type transformer full load work for a long time, and the low-voltage coil of dry-type transformer inner circle and the high-voltage coil of outer lane will produce heat in a large number, if the heat yield can not keep up with the heat production volume, then low-voltage coil and high-voltage coil are very easily burnt out, lead to the transformer unable work, also can cause the influence to the production in workshop. Therefore, the heat dissipation speed of the low-voltage coil and the high-voltage coil needs to be increased to prevent the transformer from being burnt due to overlarge load.

To solve the above problems, chinese patent publication No. CN106449017B discloses a dry-type transformer cooling device, which comprises a cooling chamber disposed inside a transformer box, the cooling chamber includes a dust-removing filtering chamber and a transformer working chamber, the transformer working chamber is disposed under the dust-removing filtering chamber, a supporting seat is disposed under the transformer box, the supporting seat includes a first supporting seat and a second supporting seat, an air inlet pipe is disposed on the upper portion of the transformer box, an induced draft fan connected to a motor is disposed on the upper portion of the air inlet pipe, an air inlet duct is connected to the lower portion of the air inlet duct, air inlet nozzles are uniformly arranged under the air inlet duct, a dust-removing filtering chamber is disposed under the air inlet nozzles, a dust-removing plate is fixed on the inner wall of the dust-removing filtering chamber, gas coolers are disposed on both sides of the lower portion of the dust-removing plate, each gas cooler includes a first gas cooler and, the gas channel lower part is equipped with main trachea, is equipped with the branch gas ware on the main trachea, and the branch gas ware left side is equipped with first bronchus, and the branch gas ware right side is equipped with the second bronchus, and first bronchus and second bronchus lower part are equipped with the iron core for running through the vertical bronchus in the transformer studio, and the cladding of the iron core outside has the coil, and vertical bronchus lower part is equipped with the pipe of giving vent to anger, and the pipe lower part of giving vent to anger is equipped with align to.

The air pipes filled with cooling gas are uniformly arranged in the transformer box body, so that the heat dissipation efficiency in the transformer is improved. When coil calorific capacity is low, can solve the heat dissipation problem of coil, but cooling device sets up outside the coil, and the heat transfer of coil inside needs certain time outside the coil when coil temperature risees, leads to the heat of coil inside to derive in time, and when the load is high, the coil still has the risk of burning out. Meanwhile, the heat dissipation efficiency of the cooling device cannot be adaptive to more or less heat of the coil, and when the heat productivity of the coil is low, the cooling device still operates in a high-power heat dissipation mode, so that energy is wasted.

Disclosure of Invention

The invention aims to provide a workshop dry-type transformer cooling device, which solves the problem of low coil heat dissipation speed in the prior art.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a workshop dry-type transformer cooling device comprises a shell and a plurality of coil groups arranged in the shell;

the coil group comprises a coil and a central pipeline; the coils are coaxially arranged and wound in a plurality of sections in the circumferential direction of the central pipeline; the adjacent two sections of the firing coils are separated by grid pads;

the coil, the grid cushion and the central pipeline are cast into a whole by epoxy resin; the central pipeline is hollow, the bottom end and the top end of the central pipeline are both opened, and the top end and the bottom end of the central pipeline both extend out of the shell.

The basic scheme principle and the beneficial effects are as follows:

1. the two adjacent sections of the firing coils are separated by the grid pads, so that heat between the two adjacent sections of the firing coils can be prevented from being mutually transferred, and the high-heat coil is prevented from transferring heat to the low-heat coil between the two adjacent sections of the firing coils;

2. the central pipeline is tightly attached to the coil, and the heat of the coil can be directly transferred to the central pipeline, so that the heat dissipation of the coil is facilitated;

3. in the low-load operation process of the dry-type transformer, the coil has low calorific value, and because the central pipeline is contacted with the coil, the heat of the coil is transferred to the central pipeline at the moment, the air in the central pipeline is heated, and the hot air rises upwards along the central pipeline and flows out from the upper end of the central pipeline to take away the heat; meanwhile, after the hot air in the central pipeline flows out, the pressure in the central pipeline is reduced, the cold air is supplemented into the central pipeline from the bottom of the central pipeline, and then the cold air is heated and rises in the central pipeline. The circulation generates a chimney effect, at the moment, the convection in the central pipeline is strong, the air flows fast, the air absorbing the heat of the coil can be quickly discharged out of the central pipeline, and the heat dissipation of the coil can be accelerated;

4. the basic scheme ensures that the coil does not consume energy while rapidly dissipating heat under the low-heating condition, and effectively saves energy.

Furthermore, the number of the coil groups is two, and the coil groups are distributed in the horizontal direction; the top ends of the central pipelines of the adjacent coil groups are communicated through a top end connecting pipeline, and the bottom ends of the central pipelines of the adjacent coil groups are communicated through a bottom end connecting pipeline;

a valve mechanism is also arranged below the joint of the central pipeline and the bottom connecting pipeline, and comprises a valve box, a first block, a first elastic air bag and a first spring;

the valve box is hollow and comprises a sealing end and an opening end, the opening end of the valve box is communicated with the central pipeline, the first blocking block comprises a front end facing the opening end of the valve box and a rear end facing the sealing end of the valve box, and the first blocking block is connected with the valve box in a sliding mode; one end of the first spring is fixedly connected with the sealing end, and the other end of the first spring is fixedly connected with the rear end of the first plugging block; the first spring is used for resetting the first block after the first block slides out of the valve box;

the first elastic air bag is positioned between the rear end of the first block and the sealing end of the valve box; the first elastic air bag is used for pushing the first block out of the valve box when being expanded;

a first groove is formed in the central pipeline, and the first groove is opposite to the open end of the valve box; the front end of the first plugging block can slide into the first groove; the first block is used for blocking the central pipeline;

the shell is also provided with an oil tank, an oil outlet part, an oil inlet part and a second elastic air bag;

the outer wall of the oil tank is fixedly connected with the outer wall of the shell, and the second elastic air bag is positioned in the oil tank;

the oil outlet part comprises an oil outlet pipe; the oil outlet pipe is vertically and fixedly arranged at the top of the oil tank, and the bottom end of the oil outlet pipe is communicated with the oil tank;

the oil inlet part comprises a transverse pipe, a second block and a second spring;

one end of the transverse pipe is communicated with the top end of the oil outlet pipe, the other end of the transverse pipe is communicated with the top end connecting pipeline, a second groove is formed in the inner wall, facing the oil outlet pipe, of the transverse pipe, and the second plugging block is located between the second groove and the oil outlet pipe; one end of the second spring is fixedly connected with the second groove, and the other end of the second spring is fixedly connected with the second blocking block;

the second spring is used for applying elasticity to the second plugging block, so that the second plugging block plugs the communication position of the oil outlet pipe and the transverse pipe.

When the dry type transformer runs under high load, the heat productivity of the coil rises, the temperature of the central pipeline rises, the temperature of a valve mechanism communicated with the central pipeline rises, a first elastic air bag in a valve box is heated to expand, a first blocking block is pushed outwards and slides into a first groove, a spring is stretched, the central pipeline is blocked by the first blocking block, and the lower end of the central pipeline is closed.

Simultaneously, the second elasticity gasbag in the oil tank is heated the inflation, and the second elasticity gasbag is heated the inflation back, and extrusion diaphragm occupies more oil tank inner space, and liquid receives the extrusion pressure increase, and liquid exerts ascending thrust to the sprue, slides in the recess after the sprue atress, and the second spring is compressed simultaneously.

When the block slides to the groove, the oil outlet pipe is communicated with the transverse pipe, and liquid in the oil tank flows into the central pipeline. When the liquid flows through the central pipeline, the heat of the central pipeline is absorbed, and the purpose of cooling the coil is achieved.

Through setting up first elasticity gasbag and second elasticity gasbag, when coil calorific capacity risees, automatically switch the forced air cooling into oil cooling, oil cooling is higher than forced air cooling radiating efficiency, can prevent that the coil is overheated.

The larger the heating value of the coil is, the larger the expansion volume of the second elastic air bag is, the larger the liquid in the oil tank is squeezed, the faster the liquid flows out, the more the liquid flows through the central pipeline in the same time, and the more heat can be absorbed. In other words, the speed of liquid flowing is positively correlated with the heat productivity of the coil, and when the heat productivity of the coil is large, the liquid flows faster, more heat is taken away, and the coil is prevented from being overheated.

Furthermore, an auxiliary oil tank, an oil pump, a collecting pipeline, an oil return pipeline, a pressure sensor, a single chip microcomputer and a driver are also arranged outside the shell;

the auxiliary oil tank is arranged at the bottom of the shell, a collecting pipeline is connected between the auxiliary oil tank and the bottom end connecting pipeline, the auxiliary oil tank is provided with an oil outlet, the oil outlet is connected with an oil pump, one end of the oil return pipeline is connected with the oil tank, and the other end of the oil return pipeline is connected with the oil pump;

the pressure sensor is positioned below the auxiliary oil tank; the pressure sensor is used for detecting the weight of the auxiliary oil tank;

the pressure sensor is in signal connection with the single chip microcomputer, and the single chip microcomputer is in signal connection with the driver; the driver is used for controlling the oil pump;

the pressure sensor sends a detected weight signal of the auxiliary oil tank to the single chip microcomputer, and when the single chip microcomputer judges that the weight signal exceeds a threshold value, the single chip microcomputer starts the oil pump through the driver.

Absorb thermal liquid in the central authorities' pipeline, after flowing into the bellytank through collecting the pipeline, the singlechip detects bellytank weight and exceeds the threshold value, and the driver starts the oil pump, and the liquid in the bellytank is pressed back to the oil tank through returning oil pipe to the oil pump. When the high-temperature liquid passes through the oil return pipeline, the liquid is cooled by heat dissipation outwards, and when the liquid returns to the oil tank again, the temperature of the liquid is reduced, and the liquid can participate in circulation again.

Further, the thickness of the first elastic airbag elastic layer is larger than that of the second elastic airbag elastic layer.

The first elastic air bag is positioned in the shell, and compared with the second elastic air bag, the heating quantity is larger, and the temperature rise is faster. When first elastic air bag deformation, second elastic air bag still does not deform, and central pipeline bottom is closed this moment, and the air no longer circulates, but in liquid has not arrived central pipeline, because there is not the heat dissipation this moment, can cause the coil temperature to rise steeply, burns out the coil easily. The thickness of the elastic layer of the first elastic air bag is larger than that of the second elastic air bag, so that the first elastic air bag can not deform too early, and the coil is prevented from being overheated and burnt out due to the discontinuity of the switching of the two heat dissipation modes.

Further, a waterproof cover is arranged at the top end of the central pipeline.

The waterproof cover can prevent rainwater from entering the central pipeline and prevent the central pipeline from being corroded by the rainwater.

Further, the coil is made of flat copper wires.

The flat copper wire has a large contact surface with the central pipeline and a good heat dissipation effect.

Drawings

FIG. 1 is a front view of a first embodiment of a plant dry type transformer cooling apparatus;

fig. 2 is an enlarged view of a portion a of fig. 1.

Detailed Description

The following is further detailed by way of specific embodiments:

reference numerals in the drawings of the specification include:

the device comprises a coil 1, a central pipeline 2, an upper connecting pipeline 3, a rectangular base 4, a lower connecting pipeline 5, a transverse pipe 6, an oil outlet pipe 7, an oil tank 8, an oil return pipeline 9, an oil pump 10, an auxiliary oil tank 11, a waterproof cover 12, a first spring 13, a first elastic air bag 14, a first groove 15, a first blocking block 16, a valve mechanism 17 and a second elastic air bag 18.

The specific implementation process is as follows:

example one

A workshop dry-type transformer cooling device comprises a rectangular base 4, a shell and a plurality of coil groups in the shell; in this embodiment, the number of coil groups is 2, and the coil groups are arranged in the horizontal direction.

The coil assembly comprises a coil 1 and a central pipe 2; the coil 1 adopts flat copper wires; the coils 1 are coaxially arranged and wound in a plurality of sections in the circumferential direction of the central pipeline 2; the adjacent two sections of the firing coils 1 are separated by grid pads; the central pipeline 2 is tightly attached to the coil 1; the coil 1, the mesh pad and the central tube 2 are cast in one piece from epoxy resin.

As shown in fig. 1, the central pipe 2 is hollow, and is open at both the upper end and the top and lower ends; the upper end and the lower end of the central pipeline 2 extend out of the transformer shell, the upper end of the central pipeline 2 is welded with a conical waterproof cover 12, an upper connecting pipeline 3 and a lower connecting pipeline 5 are welded between the central pipelines 2 of adjacent coil groups, the upper connecting pipeline 3 communicates the upper parts of the left central pipeline 2 and the right central pipeline 2, and the lower connecting pipeline 5 communicates the lower parts of the left central pipeline 2 and the right central pipeline 2.

As shown in fig. 2, a valve mechanism 17 is arranged below the joint of the central pipe 2 and the lower connecting pipe 5, and the valve mechanism 17 includes a valve box, a first block 16, a first elastic air bag 14 and a first spring 13. The opening at the left end of the valve box is communicated with the central pipeline 2, and the first blocking block 16 can slide left and right in the valve box; a first spring 13 is connected between the right side surface of the first block 16 and the left side surface of the valve box; the first spring 13 is used for resetting the first block 16 after the first block 16 slides out of the valve box

A first elastic air bag 14 is further arranged between the right side face of the first blocking block 16 and the left side face of the valve box, and the first elastic air bag 14 is used for pushing the first blocking block 16 out of the valve box when expanding.

The inner wall of the central pipeline 2 is provided with a first groove 15 in the direction opposite to the first blocking block 16, the first blocking block 16 can slide into the first groove 15, and when the first blocking block 16 slides into the first groove 15, the lower part of the central pipeline 2 is sealed by the first blocking block 16.

An oil tank 8, an oil outlet part and an oil inlet part are arranged outside the transformer shell; the oil tank 8 is vertically arranged on the top of the shell, and the bottom of the oil tank 8 is welded with the shell 4. The liquid stored in the oil tank can be oil, cooling liquid and the like, and in the embodiment, oil is adopted.

A second elastic air bag 18 is arranged in the oil tank 8, and the second elastic air bag 18 is bonded at the lower part of the oil tank 8; the first elastic air bag 14 and the second elastic air bag 18 are made of rubber, and the rubber shell of the first elastic air bag 14 is thicker than that of the second elastic air bag 18.

The oil outlet part comprises an oil outlet pipe 7; the oil outlet pipe 7 is vertically welded at the top of the oil tank 8, and the oil outlet pipe 7 is communicated with the oil tank 8.

The oil inlet part comprises a transverse pipe 6, a second block and a second spring; the horizontal pipe 6 is horizontally arranged at the top end of the oil outlet pipe 7, the left end of the horizontal pipe 6 is communicated with the top end of the oil outlet pipe 7, and the right end of the horizontal pipe 6 is communicated with the upper connecting pipe. The second block is positioned in the transverse pipe 6, a second groove capable of accommodating the second block is formed in the inner wall of the transverse pipe 6 right above the second block, a second spring is connected between the upper end of the second block and the wall of the second groove, and the second spring is used for applying elasticity to the second block; when the second spring normally extends, the second blocking block can block the communication position of the oil outlet pipe 7 and the transverse pipe 6.

The transformer shell is also provided with an auxiliary oil tank 11, an oil pump 10, a first pressure sensor, a single chip microcomputer, a driver and an oil return pipeline 9. The auxiliary oil tank 11 is arranged at the bottom of the shell, and the upper part of the auxiliary oil tank 11 is communicated with the lower connecting pipe. The first pressure sensor is arranged at the bottom of the auxiliary oil tank 11, in the embodiment, the first pressure sensor adopts a gold medal micro load sensor, and the measurement precision is high; the driver adopts an L298 chip; the singlechip adopts an AT 89C51 singlechip.

An oil outlet at the left side of the auxiliary oil tank 11 is connected with an oil pump 10, and an oil return pipeline 9 is connected with the oil pump 10 and the oil tank 8. The first pressure sensor is in signal connection with the single chip microcomputer, the single chip microcomputer is in signal connection with the driver, and the driver is in power supply connection with the oil pump 10; the first pressure sensor is used for detecting the weight of the auxiliary oil tank 11; and sending the weight signal to the single chip microcomputer, and starting the oil pump 10 by the single chip microcomputer through a driver when the single chip microcomputer judges that the weight signal exceeds a first threshold value.

The specific implementation process is as follows:

in the low-load operation process of the dry-type transformer, the coil 1 has low heat productivity, the first elastic air bag 14 contracts, the first blocking block 16 is positioned in the valve box, and the lower end of the central pipeline 2 is communicated with the outside. The second elastic air bag 18 contracts, the second block is positioned at the communication part of the oil outlet pipe 7 and the transverse pipe 6, and the oil outlet pipe 7 is sealed.

At the moment, the heat of the coil 1 is transferred to the central pipeline 2, the central pipeline 2 generates heat, the air in the central pipeline 2 rises along the central pipeline 2 after being heated, finally flows out from the upper end of the central pipeline 2, and the heat of the coil 1 is taken away while the hot air flows out; after the hot air in the central duct 2 flows out, the pressure in the central duct 2 becomes low, and the cold air flows into the central duct 2 from the lower end of the central duct 2. So circulate, produce the chimney effect, the air convection strengthens in central authorities' pipeline 2 this moment, and the air can take away the heat that coil 1 produced, reaches the effect of cooling for coil 1.

When the dry type transformer runs under high load, the heat productivity of the coil 1 rises, the temperature of the central pipeline 2 rises, the temperature of the valve mechanism 17 communicated with the central pipeline 2 rises, the first elastic air bag 14 in the valve mechanism 17 is heated to expand, the first blocking block 16 is pushed leftwards, the first blocking block 16 slides leftwards into the first groove 15, the first spring 13 is stretched, and the lower end of the central pipeline 2 is closed.

Meanwhile, the second elastic air bag 18 in the oil tank 8 is heated to expand, after the second elastic air bag 18 is heated to expand, the extrusion diaphragm occupies more internal space of the oil tank 8, the diaphragm extrudes oil, the pressure intensity of the oil is increased, the oil exerts upward thrust on the second block, the second block moves upwards into the second groove, and meanwhile, the second spring is compressed.

After the second block moves to the second groove, the oil outlet pipe 7 is communicated with the transverse pipe 6, and oil in the oil tank 8 flows into the central pipeline 2. The oil liquid flows into the auxiliary oil tank 11 through the lower connecting pipe 5 at the lower part of the central pipe 2. When fluid flows through central authorities pipeline 2, absorbs central authorities pipeline 2's heat to take away the heat along with fluid's flow, reach the purpose for coil 1 cooling.

At this time, the weight of the secondary oil tank 11 changes, the single chip microcomputer starts the oil pump 10 through the driver, the oil pump 10 at the outlet of the secondary oil tank 11 is started, and oil in the secondary oil tank 11 is pressed back into the oil tank 8 through the oil return pipeline 9. Because the oil return pipe 9 is long, when high-temperature oil passes through the oil return pipe 9, heat is emitted outwards, and when the oil returns to the oil tank 8, the temperature of the oil is reduced.

When the load of the dry-type transformer is reduced again, the heat productivity of the coil 1 is reduced, the temperature in the oil tank 8 is reduced, the second elastic air bag 18 contracts, the space in the oil tank 8 is released after the second elastic air bag 18 contracts, the pressure of oil in the oil tank 8 is reduced, the oil does not apply pressure to the second block any more, and the second block moves downwards under the action of the restoring force of the spring to block the oil outlet pipe 7.

Meanwhile, the temperature of the first elastic air bag 14 is reduced, the first elastic air bag 14 contracts, the supporting force is not applied to the first blocking block 16 any more, and the first blocking block 16 slides rightwards under the action of the restoring force of the first spring 13 and slides into the valve box. The lower end of the central tube 2 is now in communication with the outside. At which time the cooling device switches back to the air-cooling mode.

Because the oil tank 8 is vertically placed at the top of the shell, and the bottom of the oil tank 8 is welded with the shell 4, when the transformer works, oil in the oil tank 8 can absorb partial heat of the shell, so that the oil has certain temperature. If the stored low-temperature liquid easily causes the temperature of the central pipeline to be lower, and the hot air meets the central pipeline with lower temperature and is condensed into small water drops on the central pipeline, so that the central pipeline is easily corroded for a long time. After the oil liquid has a certain temperature, the temperature of the central pipeline can be prevented from being lower, hot air is prevented from being condensed into small water drops on the central pipeline, and the service life of the central pipeline can be prolonged.

Example two

The difference from the first embodiment is that a collecting barrel is arranged below the lower end of the central pipeline, and the bottom of the collecting barrel is connected with the auxiliary oil tank through a guide pipe.

Set up the convenient oil liquid that leaks out below the central pipeline of collecting vessel rear and retrieve, avoid fluid extravagant.

EXAMPLE III

The difference with the second embodiment is that the bottom of the oil tank 8 is also provided with a second pressure sensor which is in signal connection with the single chip microcomputer; when the single chip microcomputer judges that the weight signal of the first pressure sensor exceeds the first threshold value and the weight signal of the second pressure sensor is lower than the second threshold value, the single chip microcomputer starts the oil pump 10 through the driver.

When the weight signal of the second pressure sensor is lower than the second threshold value, the oil in the oil tank 8 is less, and at the moment, the oil pump 10 is started to pump back the oil, so that the oil in the oil tank 8 can be supplemented, and the oil is prevented from being too little.

The foregoing is merely an example of the present invention and common general knowledge of known specific structures and features of the embodiments is not described herein in any greater detail. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims

1. A workshop dry-type transformer cooling device comprises a shell and a plurality of coil groups arranged in the shell; the method is characterized in that:

the coil, the grid cushion and the central pipeline are cast into a whole by epoxy resin; the central pipeline is hollow, the bottom end and the top end of the central pipeline are both open, and the top end and the bottom end of the central pipeline both extend out of the shell;

the number of the coil groups is two, and the coil groups are distributed in the horizontal direction; the top ends of the central pipelines of the adjacent coil groups are communicated through a top end connecting pipeline, and the bottom ends of the central pipelines of the adjacent coil groups are communicated through a bottom end connecting pipeline;

the second spring is used for applying elasticity to the second blocking block, so that the second blocking block blocks the communication part of the oil outlet pipe and the transverse pipe;

the thickness of the first elastic airbag elastic layer is larger than that of the second elastic airbag elastic layer.

2. The plant dry-type transformer cooling device according to claim 1, wherein: the shell is also provided with an auxiliary oil tank, an oil pump, a collecting pipeline, an oil return pipeline, a pressure sensor, a singlechip and a driver outside;

3. The plant dry-type transformer cooling device according to claim 1, wherein: the top end of the central pipeline is provided with a waterproof cover.

4. The plant dry-type transformer cooling device according to claim 1, wherein: the coil is made of flat copper wires.