JPH05166639A - External cooler of gas-insulated transformer - Google Patents

Abstract

PURPOSE:To realize the external cooler, of a gas-insulated transformer, wherein it is compact and its cost is low by a method wherein the external cooler of the gas-insulated transformer is made small-sized and optimum. CONSTITUTION:The external cooler of a gas-insulated transformer is constituted in the following manner: a transformer main body 21 and the external cooler are filled with SF6 gas and connected airtightly; the SF6 gas is circulated between the transformer main body 21 and the external cooler; and a coil and an iron core which have been housed at the inside of the transformer main body 21 are cooled. The external cooler is provided with the following: a first cooler 26 provided with a flow passage which makes the SF6 gas flow nearly perpendicularly to the direction of gravitation; and a second cooler 36 provided with a flow passage which makes the SF6 gas flow nearly parallel to the direction of gravitation. (A branching loss + an aggregate loss) between an upper- part header 27 and a lower-part header 28 for the cooler and panels 31, 37 can be reduced, and the circulating power of an insulating gas can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external cooler for a gas-insulated transformer that uses an insulating gas as a coolant for a coil and an iron core inside the transformer.

[0002]

2. Description of the Related Art In recent years, with the construction of substations in buildings and underground substations, transformers that used conventional insulating oil as a cooling medium have been replaced with insulating gas such as SF gas due to safety problems such as fire prevention. _It is being replaced by a transformer that uses ₆ gas as a cooling medium. However, as is well known, since the heat transfer ability of SF ₆ gas is inferior to that of insulating oil, the transformer main body and the cooling device attached to the transformer main body become large, resulting in an increase in cost and limited space. It is difficult to install it in the space. A conventional example of such a gas insulated transformer will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan view of a main part, and FIG. 11 is a front view of the main part.

In these figures, 1 is a transformer body,
A coil and an iron core (not shown) are housed inside. An upper manifold tube 2 and a lower manifold tube 3 are provided outside the transformer body 1 so as to communicate with each other with an upper pipe 4 and a lower pipe 5 interposed. Further, the eight external coolers 6 are attached so that the open end portions 9 and 10 of the upper header 7 and the lower header 8 communicate with the upper and lower manifold tubes 2 and 3, respectively.

In the external cooler 6, a plurality of panels 11 are vertically arranged between the upper header 7 and the lower header 8 so as to be separated from each other, and a vertical space is provided inside the panel 11. Are formed and communicate with the inside of the upper header 7 and the lower header 8.

Further, the transformer body 1, the upper and lower manifolds
SF ₆ gas is filled in the space where the cold pipes 2, 3, the upper and lower pipes 4, 5 and the external cooler 6 communicate with each other,
SF ₆ gas is used to maintain the insulation performance of the transformer and is also used as a cooling medium.
The heat generated from the coil and the iron core is removed when flowing between the external cooler 6 and the external cooler 6 by natural circulation, and the panel 1 of the external cooler 6 is removed.
It radiates heat in 1.

That is, the SF ₆ gas rises while removing the heat generated from the coil and the iron core inside the transformer main body 1,
After branching left and right by the upper manifold pipe 2 through the upper pipe 4, it is further branched and flows into the upper header 7 of each external cooler 6. Here again, the SF ₆ gas is branched into each panel 11 and flows while radiating vertically downward, and then the lower header 8
Collected in. Then, the transformer main body 1 returns while being assembled by the lower manifold pipe 3 and the lower pipe 5. In addition, SF ₆
When the gas flows through the flow path of the panel 11, the air around the panel 11 is heated to generate convection, so that heat is mainly radiated.

At this time, as described above, the insulating medium SF ₆ gas, which is inferior in heat transfer ability, is used as the cooling medium instead of the insulating oil, and the height is limited when installed indoors. In order to increase the cooling capacity of the external cooler 6, the circulation flow rate can be increased within the height limit or the panel 1
It is necessary to enhance the heat transfer ability between the side wall of No. 1 and the ambient air of the panel 11.

As is well known, the branch loss + collection loss between the upper / lower headers 7 and 8 and the panel 11 increases as the SF ₆ gas flow velocity in the upper / lower headers 7 and 8 increases.
Here, the relationship between the branch loss + collection loss between the upper / lower headers 7 and 8 and the panel 11 will be described.

FIG. 12 is a graph showing an example of the relationship between the flow path cross-sectional areas of the upper and lower headers 7 and 8 and the branch loss + collection loss when the SF ₆ gas flow rate is constant. The horizontal axis is the flow path cross-sectional area of the upper and lower headers 7 and 8, and the vertical axis is the branch loss + collection loss. Thus, the larger the flow passage cross-sectional area of the upper / lower headers 7 and 8, the smaller the branch loss + collection loss.

However, in order to smoothly convect the ambient air around the panel 11 of the external cooler 6 and further promote the heat exchange in the panel 11, the upper and lower headers 7, which hinder the convection of the ambient air, It is conceivable to reduce the outer diameter of No. 8. However, if the outer diameters of the upper and lower headers 7 and 8 are reduced, the flow passage cross-sectional areas of the upper and lower headers 7 and 8 are also reduced, and branch loss + collection loss increase, and the SF ₆ gas flow rate cannot be increased.

That is, if the outer diameters of the upper and lower headers 7 and 8 are reduced in order to enhance the heat transfer capability of the external cooler 6, the SF ₆ gas flow rate will be reduced, causing a problem. Cannot be made smaller.

Therefore, when the height of the external cooler 6 cannot be increased, such as when it is installed indoors, the installation area and cost of the external cooling 6 increase due to the increase in the number of panels 11. There was a problem.

[0013]

As described above, the external cooler of the conventional gas-insulated transformer is required to obtain a predetermined cooling performance due to the limitation of the installation height and the external dimensions of each header and the like. Had a problem that the external cooler became large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small-sized and low-cost gas-insulated transformer by improving the heat dissipation performance of an external cooler.

[0015]

According to the present invention, a transformer body and an external cooler are hermetically connected by enclosing an insulating gas therein, and the insulating gas is connected between the transformer body and the external cooler. In an external cooler of a gas-insulated transformer configured to cool the coil and the iron core housed inside the transformer main body by circulating, the external cooler makes the insulating gas almost perpendicular to the gravity direction. It is characterized by comprising a first cooler having a flow passage and a second cooler having a flow passage for flowing the insulating gas substantially parallel to the gravity direction.

[0016]

In the gas-insulated transformer configured as described above, the branch loss coefficient and the collective loss coefficient between the inlet header and the outlet header of the external cooler and the panel are reduced, and the flow resistance of the insulating gas is reduced, or By increasing the circulating force of the insulating gas, the flow rate of the insulating gas can be increased and the heat dissipation capability of the external cooler can be increased.

Therefore, even if an insulating gas having a heat transfer capability inferior to that of insulating oil is used as a cooling medium, it can be installed in a limited space, and a compact and low-priced product can be realized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) A first embodiment will be described with reference to FIGS. FIG. 1 is a plan view of a main part, and FIG. 2 is a front view of the main part.

In the figure, reference numeral 21 denotes a transformer main body, in which a coil and an iron core (not shown) are housed. An upper manifold pipe 22 and a lower manifold pipe 23 are provided outside the transformer body 21 so as to communicate with each other with an upper pipe 24 and a lower pipe 25 interposed therebetween, and eight first external cooling units are provided. In the container 26, the open headers 29 and 30 of the upper header 27 and the lower header 28 have upper and lower manifold tubes 2 respectively.
It is attached so as to communicate with 2, 23.

In the external cooler (a) 26, a plurality of panels (a) 31 are vertically arranged between the upper header 27 and the lower header 28 so as to be separated from each other.
(a) A vertical space is formed inside 31.
It communicates with the inside of the upper header 27 and the lower header 28.

Further, a first header 32 and a second header 33 are attached to the upper part of the transformer main body 21 so as to communicate with the inside of the transformer main body 21 via an upper connecting pipe 34 and a lower connecting pipe 35. .. The two external coolers (b) 36 have a plurality of panels between the first header 32 and the second header 33.
(b) 37 are horizontally arranged so as to be separated from each other, and a horizontal space is formed inside the panel (b) 37 to communicate with the insides of the first header 32 and the second header 33. ing.

Further, the transformer main body 21, the upper / lower manifold pipes 22, 23, the upper / lower pipes 24, 25, the upper / lower connecting pipes 34, 35 and the external coolers (a), (b) 2
SF ₆ gas is filled in the space where ₆ , ₆ communicate with each other, and the SF ₆ gas is used as a medium for maintaining the insulating performance of the transformer and also as a cooling medium. (a), (b) Removes heat from the coil and the iron core when flowing by natural circulation between the 26, 36, and the panels (a), (of the external coolers (a), (b) 26, 36 b) 3
Heat is dissipated at 1,37.

That is, the SF ₆ gas rises while removing the heat generated from the coil and the iron core inside the transformer main body 21, is divided into two parts in the upper part inside the transformer main body 21, and one passes through the upper pipe 24 and the upper manifold. After branching left and right by the cold pipe 22, it further branches and flows into the upper header 27 of each external cooler 26. Also in this case, the SF ₆ gas is branched into each panel (a) 31, flows vertically downward while radiating heat, and then is collected in the lower header 28. And the lower manifold tube 23
The main body 21 of the transformer returns while gathering in the lower pipe 25.

The other part of the upper part inside the transformer main body 21 is divided into two parts, flows into the first header 32 through the upper connecting pipe 34, then branches into each panel (b) 37, and flows while radiating heat in the horizontal direction. And then collected in the second header 33. Then, it returns to the inside of the transformer main body 21 through the lower connecting pipe 35.

The SF ₆ gas is used for the panels (a), (b) 31,
Panels (a), (b) 31, 37 when flowing through the flow path of 37
The air around the is heated to cause convection, so that heat is mainly radiated.

As a matter of course, the above-mentioned structure is an dead space, and the external cooler is provided on the upper portion of the transformer main body 21.
(b) Since the 36 is installed, if the heat radiation area is increased by that amount and the heat radiation area equivalent to the conventional one is to be achieved, the external cooler provided on the side surface of the transformer main body 21 in comparison with the conventional method is used. The heat radiation area of is small.

However, two types of external coolers are used, and the upper and lower headers 2 of the external cooler (a) 31 provided on the side surface are used.
The SF ₆ gas flow rate in the upper and lower headers 27 and 28 also decreases due to the decrease in the SF ₆ gas flow rate in the _{7 and} 28 parts. Therefore, the upper and lower headers 27 and 28 and the panel (a)
The branch loss between 31 and the set loss becomes smaller.

Furthermore, since the SF ₆ gas flow rates of the upper and lower pipes 24 and 25 and the upper and lower manifold pipes 22 and 23 are also reduced, the branch between the upper and lower pipes 24 and 25 and the upper and lower manifold pipes 22 and 23 is reduced. Loss + collective loss and upper / lower manifold pipes 22 and 23 and upper / lower header 2
The branch loss between 7 and 28 + collective loss is also reduced. Furthermore, since it is easy to increase the flow passage cross-sectional area of the first header and the second header, it is possible to reduce the branch loss + collection loss between the panels (b) 37.

As a result, the S flowing in each panel is
The F ₆ gas flow rate increases, and the heat dissipation area of the external cooler (b) 36 installed on the upper part of the transformer main body 21 can be greatly reduced to be larger than the heat dissipation area of the external cooler (b) 36, which is compact and low in size. We can offer a price. Also, panel (a)
By shortening the length of 31, the space below the external cooler (a) can be effectively used for taking out the bushing 39.

Moreover, by adopting the structure of the above embodiment, the transformer main body 21 is increased by increasing the SF ₆ gas flow rate.
Since the flow velocity of the SF ₆ gas flowing through the flow path for cooling the coil and the iron core housed inside is also increased, the heat transfer coefficient in the flow path of the coil and the iron core is also increased. As a result, the wall temperature of the coil and the iron core is lowered, and the possibility of dielectric breakdown is further reduced. (Second Embodiment) Next, a second embodiment will be described with reference to FIGS. 3 is a plan view of a main part, and FIG. 4 is a front view of the main part.

In the figure, reference numeral 41 denotes a transformer main body, in which a coil and an iron core not shown are housed. Four external coolers (a) 42 are provided on the upper portion of the transformer body 41, and the first header 44 communicates with the inside of the transformer body 41 with the upper connecting pipe 43 interposed. The second header 45 includes two external coolers (b) 46 and an upper header 47.
The one end portion 48 that is opened and the second header 45 are attached so as to communicate with each other. The open one end 50 of the lower header 49 is attached so as to communicate with the transformer main body 41 through a manifold hole 51 and a lower connecting pipe 52.

In the external cooler (a) 42, a plurality of panels (a) 53 are horizontally arranged between the first header 44 and the second header 45 so as to be separated from each other.
(a) A horizontal space is formed inside 53,
The first header 44 and the second header 45 communicate with each other. Furthermore, between the upper header 47 and the lower header 49,
A plurality of panels (b) 54 are horizontally arranged so as to be separated from each other, and a horizontal space is formed inside the panel (b) 54, and the upper header 47 and the lower header 49 are formed.
It communicates with the inside of.

Further, the transformer body 41, the upper and lower connecting pipes 43 and 52, the manifold pipe 51, and the external cooler.
(a), the communication with the space (b) 42, 46, SF and ₆ gas is filled, SF ₆ gas is used as the cooling medium with use as to maintain the transformer insulation performance, transformer The heat generated from the coil or the iron core is removed when flowing by natural circulation between the device body 41 and the external coolers (a), (b) 42, 46, and the external coolers (a), (b) 42, 46 are removed. Panel of
(a), (b) 53 and 54 radiate heat.

That is, the SF ₆ gas rises while removing the heat generated from the coil and the iron core inside the transformer main body 41, flows through the upper pipe 43 into the first header 44, and is branched into each panel (a) 53. After flowing while radiating heat in the horizontal direction, it is collected in the second header 45. And the second header 4
5 flows into the upper header 47.

Here again, the SF ₆ gas is branched into each panel (b) 54, flows vertically downward while radiating heat, and then is collected in the lower header 49. Then, it returns to the transformer main body 41 while being assembled by the manifold pipe 51 and the lower pipe 52.

The circulation force in the case of such a configuration will be qualitatively described with reference to FIG. Figure 5 is a graph showing an example of the relationship between the external cooler height H and SF ₆ gas density ρ when the SF ₆ gas is flowing inside the external cooler.

The solid line represents the case of this embodiment, inflowing at a density ρ1 at the height H1, cooling to a density ρ2 while flowing in the horizontal direction, and further cooling while flowing vertically, and a density ρ3 at a height H2. And through the connecting pipe, height H
Introduced into the transformer at 3.

On the other hand, the broken line represents a conventional case in which panels of length (H1-H3) are installed vertically, and flows in with a density ρ1 at a height H1, is cooled while flowing vertically, and has a density at a height H3. It becomes ρ3 and is introduced into the transformer.

As is clear from the comparison between the solid line and the broken line in FIG. 5, after the SF ₆ gas flows through the external cooler in the horizontal flow path,
The circulation force in the case of flowing through the external cooler in the vertical flow path is larger than that in the case of flowing through the external cooler only in the vertical flow path by (gravitational acceleration X area of the hatched portion in FIG. 5).

Further, as in the first embodiment, the branch loss + collection loss between the upper / lower headers 47, 49 and the panel (b) 54 becomes smaller as the number of panels (b) 54 decreases. Therefore, even if the circulation force is large and the flow resistance (branch loss + collective loss) is small, the outlet densities ρ1, ρ3
In the case of FIG. 5 in which the same is true, this embodiment can be applied to a larger capacity than the conventional one.

That is, in the case of the present embodiment, even if the height of the external cooler is limited, there is an excellent circulation force of SF ₆ gas,
A large amount of SF ₆ gas can be flowed. As a result, the same effect as the first embodiment is obtained.

Further, the above-mentioned embodiment is applicable to all external coolers.
Although the case where the external cooler (b) 46 is connected to the (a) 42 has been described, only a part of the external cooler (a) 42 is used to reduce the SF ₆ gas flow velocity in the upper and lower headers. It may be configured to be connected to the external cooler (b) 46. (Third embodiment)

Next, a third embodiment will be described with reference to FIGS. 6 and 7. The same parts as those in the second embodiment are designated by the same reference numerals and will be described below. 6 is a plan view of the main part, and FIG. 7 is a front view of the main part.

In the figure, 41 is a transformer body,
42 is an external cooler (a). Then, the second header 45
By connecting the manifold tube 51 and the manifold tube 51 with each other through the conduit 55, the SF ₆ gas is supplied to the panel (a) 5 of the external cooler (a) 42.
After being cooled in 3, the second header 45 splits into two parts, and a part of SF ₆ gas is caused to flow to the external cooler (b), and the rest is supplied to the conduit 5
5 through the manifold pipe 51 and the lower pipe 52 into the cooler body 41.

With this structure, the same operation and effect as those of the second embodiment can be obtained. Furthermore, even if the capacity of the transformer is large, a large amount of SF ₆ gas can be flown to the external cooler (a) 42 with low flow resistance, and the branch between the upper and lower headers 47 and 49 and the panel (b) 54 can be made. It also has the effect of suppressing an increase in loss + collection loss, and allows more SF ₆ gas to flow inside the transformer body. Moreover, it is obvious that the shape, the cross-sectional area, the number of the conduits 55, and the like can be appropriately selected without departing from the gist of the present invention. (Fourth embodiment)

Next, a fourth embodiment will be described with reference to FIGS. 8 and 9. The same parts as those in the third embodiment are designated by the same reference numerals and will be described below. FIG. 6 is a plan view of a main part, and FIG.
Is a front view of the main part.

In the fourth embodiment, a thermometer (temperature detector) 61 is provided on the upper part of the transformer main body 41 of the third embodiment, and a flow rate adjusting valve 62 is further provided on the conduit 55 to provide the thermometer 61.
The controller 63 controls the opening degree of the flow rate adjusting balda 62 according to the temperature detected in. It is composed. That is, it is possible to detect the SF ₆ gas temperature and change the SF ₆ gas flow rate in the conduit 55 according to the temperature.

In this case, since the temperature is low when the load of the transformer is small, the circulating SF ₆ gas flow rate becomes small.
Therefore, the flow rate of SF ₆ gas in the conduit 55 is controlled by the controller 62.
To reduce the opening of the flow rate adjusting valve 62 via
The SF ₆ gas flow rate flowing to the external cooler (b) 46 is increased. By controlling in this way, since the same operation and effect as those of the second and third embodiments are obtained, it is possible to lower the temperature of the coil and the iron core with respect to all the loads from high load to low load time. This also has the effect of improving the reliability of the transformer.

In the above embodiment, the temperature of SF ₆ gas is detected, and the temperature of SF ₆ gas causes SF to flow in the conduit 55.
_{6 The} case of changing the gas flow rate was explained, but SF
Since ₆ gas temperature SF ₆ gas pressure also changes when changes may be subjected to the same control by detecting the SF ₆ gas pressure rather than SF ₆ gas temperature.

As described above, in the first to fourth embodiments, the case where the external cooler having the vertical and horizontal flow paths for vertically flowing the insulating gas is installed on both side surfaces of the transformer main body has been described. It may be provided only on one side surface of the transformer body. Further, the length and number of horizontal panels and vertical panels can be appropriately selected according to the height and area of the installation location. Further, the present invention is effective even if the horizontal panel is installed at an angle of several degrees to several tens of degrees with respect to the direction perpendicular to the direction of gravity and the vertical panel with respect to the direction parallel to the direction of gravity. Furthermore, although the present invention has described a panel type cooler, a radiator is disposed between two headers,
It can also be applied to a cooler of the type in which SF ₆ gas branches and gathers into a radiator via both headers.

[0051] In yet more embodiments has dealt with the case of SF ₆ gas is natural circulation, the SF ₆ gas blower - when forcibly circulate the like also, the flow path resistance by the same action decreases Therefore, the power consumption and size of the blower can be reduced. Further, as the insulating gas, a gas other than SF ₆ gas may be used.

[0052]

As is apparent from the above description, according to the present invention, it is possible to reduce the distance between the upper and lower headers of the external cooler and the panel and increase the circulating force of the insulating gas. The insulating gas flow rate is increased, and the heat dissipation capacity of the external cooler can be increased. Therefore, there is an effect that the size of the external cooler can be made small and optimal, and a compact and low-priced one can be provided.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of an external cooler of a gas-insulated transformer showing a first embodiment of the present invention.

FIG. 2 is a front view of the main part of the external cooler of the gas insulated transformer according to the first embodiment of the present invention.

FIG. 3 is a plan view of a main part of an external cooler of a gas-insulated transformer showing a second embodiment of the present invention.

FIG. 4 is a front view of a main part of an external cooler of a gas-insulated transformer showing a second embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating the relationship between the height H of the external cooler and the SF6 gas density.

FIG. 6 is a plan view of a main part of an external cooler of a gas-insulated transformer showing a third embodiment of the present invention.

FIG. 7 is a front view of a main part of an external cooler of a gas-insulated transformer showing a third embodiment of the present invention.

FIG. 8 is a plan view of a main part of an external cooler of a gas-insulated transformer showing a fourth embodiment of the present invention.

FIG. 9 is a front view of a main part of an external cooler of a gas-insulated transformer showing a fourth embodiment of the present invention.

FIG. 10 is a main part plan view showing an external cooler of a conventional gas-insulated transformer.

FIG. 11 is a front view of a main part showing an external cooler of a conventional gas-insulated transformer.

FIG. 12 is an explanatory diagram illustrating the relationship between branching / collection loss and the flow passage cross-sectional area of the header.

[Explanation of symbols]

 21 Transformer Main Body 22 Upper Manifold Pipe 23 Lower Manifold Pipe 24 Upper Piping 25 Lower Piping 26 External Cooler (a) (First Cooler) 27 Upper Header 28 Lower Header 31 Panel (a) 32 First Header 33 Second header 36 External cooler (b) (Second cooler) 37 Panel (b)

Claims (2)

[Claims] 1. A transformer main body and an external cooler are filled with an insulating gas and hermetically connected to each other, and the insulating gas is circulated between the transformer main body and the external cooler. An external cooler for a gas-insulated transformer configured to cool a coil and an iron core housed inside, wherein the external cooler has a flow path that causes the insulating gas to flow substantially perpendicularly to a gravity direction. An external cooler for a gas-insulated transformer, comprising a cooler and a second cooler having a flow path for allowing the insulating gas to flow substantially parallel to the direction of gravity. 2. The external cooler is configured to guide the insulating gas from the transformer body to the first cooler and then to the second cooler. An external cooler for the gas-insulated transformer according to claim 1.