A three-phase common tank current transformer for 252 kV GIS

Abstract

The present invention relates to the field of power transmission and transformation equipment. Specifically, it is a three-phase coaxial current transformer for 252 kV GIS, which includes a single-phase current transformer, an end head cover plate, an adsorbent cover, a ball valve, and a density relay. A reducing cylinder is provided between the left gas compartment insulator and the transformer housing. The current transformer support cylinder is installed inside the transformer housing. The right gas compartment insulator is connected to the transformer housing. A shielding cover is provided between the right end of the current transformer support cylinder and the right gas compartment insulator. The junction box fixes the sealed terminal plate on the transformer housing. The end head cover plate is installed on the upper end of the transformer housing. The adsorbent cover and the ball valve are installed on the end head cover plate. The density relay is installed on the ball valve. Compared with the prior art, the structure of the three-phase current transformer is simplified, it can be applied to GIS products with voltages of 252 kV and above, and a single sealed terminal plate is shared inside, which improves the reliability of the CT and significantly reduces the manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the field of power transmission and transformation equipment, and more specifically, to a three-phase coaxial current transformer for 252 kV GIS. Background Art

[0002] Due to its small footprint, high reliability, and strong safety, GIS is increasingly adopted by the State Grid to replace traditional high-voltage switch technologies. The current transformer is one of the most important components of GIS, used for the measurement and protection of GIS, distributed on both sides of the circuit breaker in GIS, and has two structures: built-in and external, with the built-in structure being the main one.

[0003] Currently, the built-in current transformer structures of 252 kV GIS manufacturers are mainly divided into two categories: one is the "three-phase three-barrel" current transformer, which is used by most GIS manufacturers; the other is the "three-phase one-barrel" current transformer, which can only be used in combination with a three-phase coaxial disconnector switch. However, when this disconnector switch is applied to the bus side, it does not meet the requirements of the "18 anti-measures of the State Grid" that "for 252 kV and above GIS bus disconnectors, the design structure of sharing the same compartment with the bus is prohibited". Currently, only ABB and a few domestic manufacturers apply it.

[0004] According to the latest acceptance requirements of the State Grid that "the circuit breaker and the current transformer require separate gas compartments", the "three-phase three-barrel" current transformer of the original split-type GIS requires a separate gas compartment for each phase current transformer, and adsorbents, explosion-proof films, and density relays need to be installed, which complicates the product structure and significantly increases the cost.

[0005] Therefore, it is very necessary to design a three-phase coaxial current transformer for 252 kV GIS. Summary of the Invention

[0006] The present invention breaks through the problems of the prior art and designs a three-phase coaxial current transformer for 252 kV GIS.

[0007] To achieve the above object, the present invention designs a three-phase coaxial current transformer for 252 kV GIS, which includes single-phase current transformers, a transformer housing, a sealed terminal board, a junction box, an end cover plate, an adsorbent cover, a ball valve, and a density relay. Three single-phase current transformers are installed side by side in the transformer housing. The single-phase current transformer includes a left gas compartment insulator, a contact seat, a reducing cylinder, a conductive rod, a current transformer support cylinder, a current transformer coil, a transformer lead wire, a right gas compartment insulator, and a shielding cover. Contact seats are installed on both the left gas compartment insulator and the right gas compartment insulator, and the conductive rod is installed on the contact seat. One end of the left gas compartment insulator is connected to the reducing cylinder, and the other end of the reducing cylinder is connected to the transformer housing. The current transformer support cylinder is installed inside the transformer housing, and the left end of the current transformer support cylinder is fixed inside the transformer housing. The right gas compartment insulator is connected to the transformer housing. A shielding cover is provided between the right end of the current transformer support cylinder and the right gas compartment insulator. The current transformer coil is installed on the current transformer support cylinder. One end of the transformer lead wire is led out from the current transformer coil, and the other end is connected to the sealed terminal board. The junction box fixes the sealed terminal board on the transformer housing. The end cover plate is installed on the upper end of the transformer housing. The adsorbent cover and the ball valve are installed on the end cover plate, and the density relay is installed on the ball valve.

[0008] The adsorbent cover is filled with adsorbent.

[0009] The transformer housing is a welded housing or a cast housing.

[0010] The inside of the current transformer support cylinder is an independent gas chamber.

[0011] Three single-phase current transformers share one density relay.

[0012] Compared with the prior art, the present invention simplifies the structure of the three-phase current transformer, can be applied to GIS products with voltages of 252 kV and above, and shares a sealed terminal board inside, improving the reliability of the CT and significantly reducing the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic structural diagram of the present invention.

[0014] Figure 2 is a top view of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be further described in conjunction with the accompanying drawings.

[0016] Combined with Figures 1 to 2, the present invention designs a three-phase coaxial current transformer for 252 kV GIS, which includes single-phase current transformers, a transformer housing 6, a sealed terminal board 9, a junction box 10, an end cover plate 13, an adsorbent cover 14, a ball valve 16, and a density relay 17. Three single-phase current transformers are installed side by side in the transformer housing 6. The single-phase current transformer includes a left gas compartment insulator 1, a contact base 2, a reducing cylinder 3, a conducting rod 4, a current transformer support cylinder 5, a current transformer coil 7, a transformer lead wire 8, a right gas compartment insulator 11, and a shielding cover 12. Contact bases 2 are installed on both the left gas compartment insulator 1 and the right gas compartment insulator 11, and the conducting rod 4 is installed on the contact base 2. One end of the left gas compartment insulator 1 is connected to the reducing cylinder 3, and the other end of the reducing cylinder 3 is connected to the transformer housing 6. The transformer housing 6 is a welded housing or a cast housing. The current transformer support cylinder 5 is installed inside the transformer housing 6. The left end of the current transformer support cylinder 5 is fixed inside the transformer housing 6. The right gas compartment insulator 11 is connected to the transformer housing 6. A shielding cover 12 is provided between the right end of the current transformer support cylinder 5 and the right gas compartment insulator 11. The interior of the current transformer support cylinder 5 is an independent gas chamber. The current transformer coil 7 is installed on the current transformer support cylinder 5. One end of the transformer lead wire 8 is led out from the current transformer coil 7, and the other end is connected to the sealed terminal board 9. The junction box 10 fixes the sealed terminal board 9 on the transformer housing 6. The end cover plate 13 is installed on the upper end of the transformer housing 6. The adsorbent cover 14 and the ball valve 16 are installed on the end cover plate 13. The adsorbent cover 14 is filled with an adsorbent 15. The density relay 17 is installed on the ball valve 16, and the three single-phase current transformers share one density relay 17.

[0017] By sharing one sealed terminal board 9 among the three-phase transformers, the present invention simplifies the structure and improves the reliability of the CT. Different from common current transformers, the present invention does not have a connecting gas pipe, but adopts gas compartment insulators, a shielding cover 12, a ball valve 16, etc., which not only ensures the sealing inside the transformer, but also ensures the insulation distance and reduces the manufacturing cost.

Claims

1. A three-phase common tank current transformer for 252 kV GIS, comprising a single-phase current transformer, a transformer housing (6), a sealing terminal board (9), a junction box (10), an end head cover plate (13), an adsorbent cover (14), a ball valve (16), and a density relay (17), characterized in that: Three single-phase current transformers are installed side by side inside the current transformer housing (6). The single-phase current transformer includes a left gas compartment insulator (1), a contact base (2), a reducing cylinder (3), a conductive rod (4), a current transformer support cylinder (5), a current transformer coil (7), a current transformer lead wire (8), a right gas compartment insulator (11), and a shielding cover (12). Contact bases (2) are installed on both the left gas compartment insulator (1) and the right gas compartment insulator (11). The conductive rod (4) is installed on the contact base (2). One end of the left gas compartment insulator (1) is connected to the reducing cylinder (3), and the other end of the reducing cylinder (3) is connected to the current transformer housing (6). The current transformer support cylinder (5) is installed inside the current transformer housing (6). The left end of the current transformer support cylinder (5) is fixed inside the current transformer housing (6). The right gas compartment insulator (11) is connected to the current transformer housing (6). A shielding cover (12) is provided between the right end of the current transformer support cylinder (5) and the right gas compartment insulator (11). The inside of the current transformer support cylinder (5) is an independent gas chamber. The current transformer coil (7) is installed on the current transformer support cylinder (5). One end of the current transformer lead wire (8) is led out from the current transformer coil (7), and the other end is connected to the sealed terminal board (9). The junction box (10) fixes the sealed terminal board (9) on the current transformer housing (6). The end head cover plate (13) is installed on the upper end of the current transformer housing (6). The adsorbent cover (14) and the ball valve (16) are installed on the end head cover plate (13). The density relay (17) is installed on the ball valve (16). The three single-phase current transformers are commonly connected to the same density relay (17).

2. A three-phase coaxial current transformer for 252 kV GIS according to claim 1, characterized in that: The adsorbent cover (14) is filled with an adsorbent (15).

3. A three-phase coaxial current transformer for 252 kV GIS according to claim 1, characterized in that: The current transformer housing (6) is a welded housing or a cast housing.

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