A forced air-cooled current transformer mounting structure

Abstract

This utility model discloses a forced air-cooled current transformer installation structure. It includes a tubular busbar housing and a tubular busbar conductor coaxially located at the center of the busbar housing. A current transformer is coaxially mounted in the middle of the busbar conductor, and the cylindrical body of the current transformer is axially positioned between the busbar housing and the busbar conductor. An outer air duct and an inner air duct are formed between the cylindrical body, the busbar housing, and the busbar conductor, respectively. The cross-sectional area of ​​the inner air duct is larger than that of the outer air duct. Simultaneously, the distance between the current transformer and the busbar conductor is greater than the distance between the current transformer and the busbar housing. The advantages are: the increased inner diameter of the current transformer ensures that the distance L between the busbar conductor and the current transformer is not less than the conductor-to-ground safety distance for the corresponding voltage level. Therefore, it is unnecessary to install an equipotential bonding between the busbar conductor and the current transformer, thus eliminating the risk of the equipotential bonding being broken by strong winds, leading to a short circuit to ground in the busbar conductor.

Description

Technical Field

[0001] The utility model relates to auxiliary equipment for high-current forced air-cooled isolated-phase enclosed busbars, in particular to a forced air-cooled current transformer mounting structure. Background Art

[0002] For high-current isolated-phase enclosed busbars, especially those supporting units of 1250MW and above, forced air cooling devices are mostly equipped. However, the traditional current transformer mounting structure is difficult to ensure good operation performance under high air flow. Firstly, the equipotential connection between the current transformer and the conductor usually adopts flexible wires or springs, and these flexible equipotential connections are prone to breakage risk when exposed to a high wind speed environment for a long time, which further causes conductor-to-ground short circuit faults; secondly, the presence of the current transformer increases wind resistance and reduces the cooling effect of the forced air cooling device on the busbar conductor and the busbar enclosure; in addition, the large-flow cooling air will produce sharp howling when passing through the narrow gaps between the current transformer and the conductor / enclosure, aggravating the noise pollution in the plant. Summary of the Invention

[0003] The technical problem to be solved by the utility model is to provide a forced air-cooled current transformer mounting structure that balances safety and cooling effect and can adapt to the forced air cooling environment.

[0004] In order to solve the above technical problem, the forced air-cooled current transformer mounting structure of the utility model comprises a tubular busbar enclosure and a tubular busbar conductor coaxially located at the center of the busbar enclosure, a current transformer is coaxially arranged in the middle of the busbar conductor, and the cylindrical main body of the current transformer is axially arranged between the busbar enclosure and the busbar conductor; an outer air duct and an inner air duct are formed between the cylindrical main body and the busbar enclosure and the busbar conductor respectively, the cross-sectional area of the inner air duct is larger than that of the outer air duct, and the distance between the current transformer and the busbar conductor is greater than the distance between the current transformer and the busbar enclosure.

[0005] The ratio of the cross-sectional area of the outer air duct to the inner air duct is 4:6.

[0006] The outer diameter of the mounting section of the busbar enclosure corresponding to the mounting position of the cylindrical main body is larger than the outer diameters of other main body parts.

[0007] The outer diameter of the mounting section of the busbar conductor corresponding to the mounting position of the cylindrical main body is smaller than that of other main body parts, and the wall thickness thereof is larger than that of other main body parts.

[0008] The sum of the cross-sectional areas of the outer air duct and the inner air duct at the mounting position of the cylindrical main body is not less than the cross-sectional area between the busbar enclosure and the busbar conductor at other parts.

[0009] The current transformer is fixed on the busbar enclosure through support bolts or adjusting bolts.

[0010] The busbar housing at the location of the adjusting bolt is covered with a protective box.

[0011] A secondary output box connected to a current transformer is provided below the busbar casing.

[0012] The connection between the mounting section of the busbar housing and other main components is a sloping transition structure.

[0013] Advantages of this utility model: (1) The cross-sectional area of ​​the inner air duct is larger than that of the outer air duct, and the distance between the current transformer and the bus conductor is greater than that between the current transformer and the bus shell; the outer diameter of the bus conductor is reduced and its thickness is increased, so that the conductive cross-sectional area remains unchanged while the outer diameter is reduced; the inner diameter of the current transformer is increased so that the distance L between the bus conductor and the current transformer is not lower than the safety distance between the conductor and the ground of the corresponding voltage level. Since the distance L is not lower than the safety distance, there is no risk of discharge between the bus conductor and the current transformer. Therefore, it is not necessary to set up an equipotential connection between the bus conductor and the current transformer, thereby eliminating the risk of the equipotential connection being broken by strong wind and causing a short circuit between the bus conductor and the ground. (2) Sufficient space is formed between the current transformer and the busbar casing and the busbar conductor to effectively compensate for the ventilation obstruction caused by the current transformer occupying the original air duct volume, and to ensure that the total ventilation cross-sectional area of ​​the outer air duct and the inner air duct is not less than the original annular air duct cross-section, thereby improving the ventilation efficiency of the forced air cooling system and ensuring the heat dissipation safety of the busbar system when operating at high current. (3) The current transformer is installed along the axial direction of the bus conductor and fixed to the bus shell by support bolts or adjusting bolts. The structure is compact and the installation method is flexible. It is easy to install and convenient for later maintenance or replacement. At the same time, the external protection box structure prevents the adjusting bolts from being exposed, thus improving the safety and insulation performance of the device. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the installation structure of the forced air-cooled current transformer of this utility model; Figure 2 This is a sectional view of the installation structure of the forced air-cooled current transformer of this utility model; Figure 3 This is a ventilation diagram of the forced air-cooled current transformer installation structure of this utility model. Detailed Implementation

[0015] The forced air-cooled current transformer installation structure of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0016] The forced air-cooled current transformer mounting structure includes a tubular busbar housing 2 and a tubular busbar conductor 3 coaxially located at the center of the busbar housing 2. A current transformer 1 is coaxially mounted in the middle of the busbar conductor 3. The cylindrical body 6 of the current transformer 1 is axially positioned between the busbar housing 2 and the busbar conductor 3. An outer air duct 4 and an inner air duct 5 are formed between the cylindrical body 6, the busbar housing 2, and the busbar conductor 3, respectively. The cross-sectional area of ​​the inner air duct 5 is larger than that of the outer air duct 4. At the same time, the distance between the current transformer 1 and the busbar conductor 3 is greater than the distance between the current transformer 1 and the busbar housing 2. After thermal balance calculation of the enclosed busbar, when thermal balance is reached, the distance between the busbar housing and the busbar conductor 3 is... The heat generation ratio of the conductors is approximately 4:6. Correspondingly, the cross-sectional areas of the outer air duct 4 and the inner air duct 5 are rationally allocated, with their ratio controlled at approximately 4:6, so that the cooling air's heat dissipation effect on the busbar casing 2 and the busbar conductor 3 is more balanced. Specifically, the outer diameter of the section of the cylindrical body 6 corresponding to the installation position of the busbar casing 2 is larger than the outer diameter of other main body parts; the outer diameter of the section of the cylindrical body 6 corresponding to the installation position of the busbar conductor 3 is smaller than the outer diameter of other main body parts, but its wall thickness is greater than that of other main body parts; and the sum of the cross-sectional areas of the outer air duct 4 and the inner air duct 5 at the installation position of the cylindrical body 6 is not less than the cross-sectional areas of other parts of the busbar casing 2 and the busbar conductor 3. Because the cross-sectional area between conductors 3 is not reduced and the duct adopts a smooth transition, the wind resistance at this structure is very small, the air volume is almost unaffected, and the wind speed is almost unchanged, so there will be no whistling phenomenon. In order to maximize the cross-sectional area of ​​the outer duct 4, the connection between the installation section of the busbar shell 2 and other main parts is set as a sloping transition structure. The current transformer 1 is fixed to the busbar shell 2 by support bolts 11 or adjusting bolts 12. A secondary outlet box 14 connected to the current transformer 1 is set at the bottom of the busbar shell 2. The outlet box 14 uses a partition with terminals to separate the inside and outside of the busbar to prevent air from entering. To prevent leakage of the current transformer, the airflow is distributed according to the ratio of heat generation of the busbar casing 2 and the busbar conductor 3. The busbar with higher heat generation receives a larger airflow, which makes the cooling effect of the cooling air on the busbar casing 2 and the busbar conductor 3 more balanced, maximizing the cooling effect of the cooling air. Due to the increased volume of the current transformer, the weight of the current transformer also increases accordingly. The number of support bolts 11 of the current transformer is increased to 8 sets. The fixed support bolts 11 are installed on the inside of the casing, and the adjusting bolts 12 are installed on the outside, which is convenient for the installers to operate. The busbar casing 2 where the adjusting bolts 12 are located is covered with a protective box to ensure that the gas inside the enclosed busbar does not leak.

Claims

1. A forced air-cooled current transformer mounting structure, comprising a tubular busbar housing (2) and a tubular busbar conductor (3) coaxially located at the center of the busbar housing (2), characterized in that: A current transformer (1) is coaxially provided in the middle of the bus conductor (3). The cylindrical body (6) of the current transformer (1) is axially arranged between the bus shell (2) and the bus conductor (3). An outer air duct (4) and an inner air duct (5) are formed between the cylindrical body (6), the bus shell (2), and the bus conductor (3), respectively. The cross-sectional area of ​​the inner air duct (5) is larger than that of the outer air duct (4). At the same time, the distance between the current transformer (1) and the bus conductor (3) is greater than the distance between the current transformer (1) and the bus shell (2).

2. The forced air-cooled current transformer mounting structure according to claim 1, characterized in that: The ratio of the cross-sectional area of ​​the outer air duct (4) to the inner air duct (5) is 4:

6.

3. The forced air-cooled current transformer mounting structure according to claim 1, characterized in that: The outer diameter of the mounting section of the cylindrical body (6) corresponding to the mounting position of the busbar shell (2) is larger than the outer diameter of other main body parts.

4. The forced air-cooled current transformer mounting structure according to claim 1, characterized in that: The outer diameter of the installation section of the cylindrical body (6) corresponding to the installation position of the bus conductor (3) is smaller than that of other main body parts and the wall thickness is greater than that of other main body parts.

5. The forced air-cooled current transformer mounting structure according to claim 1, characterized in that: The sum of the cross-sectional areas of the outer air duct (4) and the inner air duct (5) at the installation position of the cylindrical body (6) is not less than the cross-sectional area between the busbar shell (2) and the busbar conductor (3) of the other parts.

6. The forced air-cooled current transformer mounting structure according to claim 1, characterized in that: The current transformer (1) is fixed to the busbar housing (2) by a support bolt (11) or an adjusting bolt (12).

7. The forced air-cooled current transformer mounting structure according to claim 6, characterized in that: A protective box covers the busbar housing (2) at the location of the adjusting bolt (12).

8. The forced air-cooled current transformer mounting structure according to claim 1, characterized in that: A secondary output box (14) connected to the current transformer (1) is provided below the busbar casing (2).

9. The forced air-cooled current transformer mounting structure according to claim 3, characterized in that: The connection between the mounting section of the busbar housing (2) and other main parts is a sloped transition structure.

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