Voltage limiter with secondary protection gap

Abstract

The application is a secondary protection gap voltage limiter, which solves the problem of power line trip after the protection gap is damaged by lightning. The lower end of the insulating rod is connected with the steel foot, and the upper part of the insulating rod and the first silicone rubber sheath are connected with multiple annular zinc oxide resistance sheets and annular electrodes from top to bottom. The annular electrodes are connected with the upper discharge electrode through a conductor. The angular connecting seat is sleeved on the steel foot, and the top end of the angular connecting seat is provided with a secondary discharge electrode. The shell is embedded with the first base, the first base is connected with the angular connector, and the shell is connected with the first base through a hinge. When the limiter fails, the shell rotates around the hinge. The upper end of the hot melt body in the shell is fixedly connected with the second base at the upper end of the shell, and the lower end of the hot melt body is fixedly connected with the mounting bolt. The upper discharge electrode and the lower discharge electrode form a first air gap, and the secondary discharge electrode and the upper discharge electrode form a second air gap.

Description

Technical Field

[0001] This invention relates to lightning protection and voltage limiting devices for power lines. Background Technology

[0002] Existing power line lightning protection and voltage limiting devices consist of only one protective gap. A zinc oxide resistance element in the device is connected in series with this gap between the power line and the tower. Under normal circumstances, the zinc oxide resistance element is in a high-resistance state, sharing the power line's frequency voltage with the series-connected fixed gap. When a lightning strike occurs, the zinc oxide resistance element in the device becomes low-resistance, and the lightning current discharges through the low-resistance zinc oxide resistance element, breaking down the fixed gap. After repeated lightning strikes or failure of the outer sheath seal of the zinc oxide resistance element, the resistance of the zinc oxide resistance element drops significantly, and the fixed gap can no longer withstand the power line's frequency voltage, resulting in breakdown and causing grounding or short-circuit tripping. Summary of the Invention

[0003] The purpose of this invention is to provide a device with a secondary protective gap voltage limiter that, after the zinc oxide resistor fails, increases the protective gap to withstand the power frequency voltage of the power line, while still providing lightning protection and voltage limiting functions for the power line.

[0004] This invention is implemented as follows:

[0005] like Figure 1As shown: A voltage limiter with secondary protection gap, characterized in that the upper end of the insulating rod 22 is fixedly connected to the wire mounting base 23, and the lower end is fixedly connected to the steel foot 14. The upper part of the insulating rod 22 is wrapped with a first silicone rubber sheath 18 and a first umbrella skirt 20. Between the upper part of the insulating rod 22 and the first silicone rubber sheath 18, there are multiple annular zinc oxide resistance plates 19 and annular electrodes 17 from top to bottom. The annular electrodes 17 are connected to the upper discharge electrode 25 through a conductor 24. The conductor 24 and the upper discharge electrode 25 are wrapped with a second silicone rubber sheath 26. The lower part of the insulating rod 22 is wrapped with a third silicone rubber sheath 15 and a second umbrella skirt 16. One side of the angled connector 10 has a connecting flange at the lower end, which is fitted onto the steel foot 14 through a U-shaped clamp 13. The connector 10 is fastened to the steel foot 14 with two nuts 11. The other side of the angled connector 10 has a bolt hole in the middle. The angled connector 10 is made of conductive material, and the top of the angled connector 10 has a... There is a secondary discharge electrode 27. The power frequency arc cutter consists of a housing 5 and a first base 34. The housing 5 is embedded with the first base 34. The first base 34 is connected to the angle connector 10 by bolts 8 and nuts 9. The housing 5 is then connected to the first base 34 by a hinge 7. When the pressure limiter fails, the housing 5 tilts and falls off, no longer embedded with the first base 34. The housing 5 rotates around the hinge 7. The upper end of the hot melt 6 inside the housing 5 is fixedly connected to the second base 3 at the upper end of the housing. The second base is connected to the lower discharge electrode 2. The lower end of the hot melt 6 is fixedly connected to the bolts 8. The hot melt 6 and the base 3 are tightly pulled onto the angle connector 10 by the installation bolts 8 and nuts 9. A first air gap 1 is formed between the upper discharge electrode 25 and the lower discharge electrode 2. A second air gap 28 is formed between the secondary discharge electrode 27 and the upper discharge electrode 25. The second air gap is larger than the first air gap. The housing 5 and the lower discharge electrode 2 are covered with an outer sheath 4.

[0006] like Figure 2As shown: The upper end of the insulating rod 22 is fixedly connected to the wire mounting base 23, and the lower end is fixedly connected to the steel foot 14. The upper part of the insulating rod 22 is wrapped with a first silicone rubber sheath 18 and a first umbrella skirt 20. Between the upper part of the insulating rod 22 and the first silicone rubber sheath 18, there are multiple annular zinc oxide resistance plates 19 and annular electrodes 17 from top to bottom. The annular electrodes 17 are connected to the upper discharge electrode 25 through a conductor 24. The conductor 24 and the upper discharge electrode 25 are wrapped with a second silicone rubber sheath 26. The lower part of the insulating rod 22 is wrapped with... The third silicone rubber sheath 15 and the second umbrella skirt 16 are wrapped around the angled connector 10. One side of the angled connector 10 has a connecting flange at its lower end, which is fitted onto the steel foot 14 via a U-shaped clamp 13. Two nuts 11 are used to fasten the connector 10 to the steel foot 14. The other side of the angled connector 10 has a bolt hole in the middle. The angled connector 10 is made of conductive material, and its top has a secondary discharge electrode 27. The power frequency arc cutter consists of a housing 5 and a first base 34. The housing 5 and the first base... 34 is fitted together. The connection between the housing and the first base is sealed with single-component silicone rubber. The first base 34 is connected to the angle connector 10 by bolts 8 and nuts 9. The housing 5 is then connected to the first base 34 by hinge 7. When the pressure limiter fails, the housing 5 tilts and falls off, no longer fitting with the first base 34. The housing 5 then rotates around the hinge 7. The upper end of the spring 29 inside the housing 5 is connected to the second base 3. The second base is connected to the lower discharge electrode 2. The lower end of the spring 29 is connected to the upper end of the nail gun cartridge 32. The heating resistor 30 is connected, and the lower end of the heating resistor 30 is connected to the nail gun cartridge 32. In extreme cases, the heating resistor 30 continuously generates heat, which detonates the nail gun cartridge. In the product design, the nail gun cartridge 32 is located in the upper hole of the bolt 8. A first air gap 1 is formed between the upper discharge electrode 25 and the lower discharge electrode 2. A second air gap 28 is formed between the secondary discharge electrode 27 and the upper discharge electrode 25. The second air gap is larger than the first air gap. The outer casing 5 and the lower discharge electrode 2 are covered with an outer sheath 4.

[0007] The power line voltage is 10-500KV, the distance of the second air gap 28 is 90-4300mm, and the distance of the first air gap 1 is between 30-2300mm.

[0008] When the power line voltage is 10kV, and four zinc oxide resistors 19 are used, each with a thickness of 24mm, and the distance of the first air gap 1 is 30-80mm, the 10kV power line operating voltage is jointly borne by the four zinc oxide resistors 19 and the first air gap 1 connected in series. When the zinc oxide resistors 19 are damaged or their seals are damaged, causing a significant drop in resistance, the first air gap 1 can no longer bear the 10kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap 1 and activate the second air gap 28. The distance of the second air gap 28 is 95-160mm. The second air gap 28 can independently bear the 10kV power line operating voltage, and the lightning impulse discharge voltage does not exceed 160kV.

[0009] When the power line voltage is 10kV, and three zinc oxide resistors 19 are used, each with a thickness of 24mm, and the distance of the first air gap 1 is 50-100mm, the 10kV power line operating voltage is jointly borne by the three zinc oxide resistors 19 and the first air gap 1 connected in series. When the zinc oxide resistors 19 are damaged or their seals are damaged, causing a significant drop in resistance, the first air gap 1 can no longer bear the 10kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap 1 and activate the second air gap 28. The distance of the second air gap 28 is 95-160mm. The second air gap 28 can bear the 10kV power line operating voltage independently, and the lightning impulse discharge voltage does not exceed 160kV.

[0010] When the power line voltage is 35kV, and 11-15 zinc oxide resistors (19) are used, each with a thickness of 24mm, and the distance of the first air gap (1) is 150-260mm, the 35kV power line operating voltage is jointly borne by the zinc oxide resistors (19) and the series-connected first air gap (1). If the zinc oxide resistor (19) is damaged, or its seal is damaged, causing a significant drop in resistance, the first air gap (1) can no longer withstand the 35kV power line operating voltage. In this case, the power frequency arc cutter is activated, cutting off the first air gap (1), and the second air gap (28) is activated. The distance of the second air gap (28) is 290-480mm. The second air gap (28) can independently withstand the 35kV power line operating voltage, and the lightning impulse discharge voltage does not exceed 350kV.

[0011] For a power line voltage of 110kV, when using 26-36 zinc oxide resistors 19, each with a thickness of 24mm, the distance of the first air gap 1 is 350-650mm. Under normal operation, the zinc oxide resistors 19 and the first air gap 1 in series jointly bear the 110kV power line operating voltage. When the zinc oxide resistors 19 are damaged or their seals are damaged, causing a significant drop in resistance, the first air gap 1 can no longer bear the 110kV power line operating voltage. In this case, the power frequency arc cutter is activated to cut off the first air gap 1, and the second air gap 28 is activated. The distance of the second air gap 28 is 700-1200mm. The second air gap 28 can independently bear the 110kV power line operating voltage, and the lightning impulse discharge voltage does not exceed 690kV.

[0012] For a power line voltage of 220kV, when using 50-70 zinc oxide resistors 19, each resistor has a thickness of 24mm. The distance of the first air gap 1 is 600-1100mm. Under normal operation, the zinc oxide resistors 19 and the first air gap 1 in series jointly bear the 220kV power line operating voltage. When the zinc oxide resistors 19 are damaged or their seals are damaged, causing a significant drop in resistance, the first air gap 1 can no longer bear the 220kV power line operating voltage. In this case, the power frequency arc cutter is activated to cut off the first air gap 1, and the second air gap 28 is activated. The distance of the second air gap 28 is 1300-2100mm. The second air gap 28 can independently bear the 220kV power line operating voltage, and the lightning impulse discharge voltage does not exceed 1200kV.

[0013] For a power line voltage of 500kV, when using 100-140 zinc oxide resistors 19, each resistor has a thickness of 22.5mm. The distance of the first air gap 1 is 1400-2300mm. Under normal operation, the zinc oxide resistors 19 and the first air gap 1 in series jointly bear the 500kV power line operating voltage. When the zinc oxide resistors 19 are damaged or their seals are damaged, causing a significant drop in resistance, the first air gap 1 can no longer bear the 500kV power line operating voltage. In this case, the power frequency arc cutter is activated to cut off the first air gap 1, and the second air gap 28 is activated. The distance of the second air gap 28 is 2100-4300mm. The second air gap 28 can independently bear the 500kV power line operating voltage, and the lightning impulse discharge voltage does not exceed 2100kV.

[0014] The advantages of this invention are as follows:

[0015] Even if the first protective gap is damaged by lightning, the second protective gap still exists. The second protective gap can withstand the power frequency voltage of the power line and still provides lightning protection and voltage limiting functions for the power line. Attached Figure Description

[0016] Figure 1 This is one of the structural diagrams of the present invention.

[0017] Figure 2 This is the second structural diagram of the present invention.

[0018] Figure 3 This is a structural diagram of the first protective gap after it was damaged by lightning.

[0019] Figure 4 This is one of the structural diagrams of a traditional pressure limiter.

[0020] Figure 5 This is the second diagram of a traditional pressure limiter. Detailed Implementation Example 1

[0021] The insulating rod 22 is equipped with a secondary protection gap voltage limiter. Its upper end is fixedly connected to the conductor mounting base 23, and its lower end is fixedly connected to the steel foot 14. The upper part of the insulating rod 22 is covered with a first silicone rubber sheath 18 of a first umbrella skirt 20. Between the upper part of the insulating rod 22 and the first silicone rubber sheath 18, there are multiple annular zinc oxide resistance plates 19 and annular electrodes 17 from top to bottom. The annular electrodes 17 are connected to the upper discharge electrode 25 via a conductor 24. The conductor 24 and the upper discharge electrode 25 are covered with a second silicone rubber sheath 26. The lower part of the insulating rod 22 is covered with a third silicone rubber sheath 15 of a second umbrella skirt 16. One side of the angle connector 10 has a connecting flange at its lower end, which is fitted onto the steel foot 14 via a U-shaped clamp 13. Two nuts are used to fasten the angle connector 10 to the side of the steel foot 14. The other side of the angle connector 10 has a bolt hole in the middle. The angle connector 10 is made of conductive material. The top of the angle connector 10... The power frequency arc cutter is equipped with a secondary discharge electrode 27. It consists of a housing 5 and a first base 34. The housing 5 is embedded with the first base 34. The first base 34 is connected to the angle connector 10 by bolts 8 and nuts 9. The housing 5 is then connected to the first base 34 by a hinge 7. The second base 3 is connected to the lower discharge electrode 2. When the pressure limiter fails, the housing 5 tilts and falls off, no longer embedded with the first base 34. The housing 5 rotates around the hinge 7. The upper end of the hot melt 6 inside the housing 5 is fixedly connected to the second base 3 at the upper end of the housing. The lower end of the hot melt 6 is fixedly connected to the bolts 8. The hot melt 6 and the second base 3 are tightly pulled onto the angle connector 10 by the installation bolts 8 and nuts 9. A first air gap 1 is formed between the upper discharge electrode 25 and the lower discharge electrode 2. A second air gap 28 is formed between the secondary discharge electrode 27 and the upper discharge electrode 25. The housing 5 and the lower discharge electrode 2 are covered with an outer sheath 4.

[0022] The distance of the second air gap 28 shall not be less than 90mm, and the distance of the first air gap 1 shall be between 85-30mm.

[0023] The principle is as follows: The power line is fixed in the wire groove of the conductor mounting base 23. When the power line is struck by lightning, the overvoltage generated by the lightning strike passes through the conductor mounting base 23—annular zinc oxide resistor 19—annular electrode 17—conductor 24—upper discharge electrode 25—air gap 1—lower discharge electrode 2—thermal melt 6—mounting bolt 8—connecting seat 10—steel foot 14—mounting bolt 12—tower mounting base—ground. Figure 3 As shown, when the annular zinc oxide resistor 19 is damaged, gap 1 cannot cut off the power frequency arc, the hot melt 6 melts, and the tilted power frequency arc cutter falls off. The first gap 1 is elongated, and its length is greater than the air gap 28 formed by the upper discharge electrode 25 and the secondary discharge electrode 27. The second protective gap 28 is still effective, and the power line still has lightning protection and voltage limiting functions.

[0024] like Figure 1 As shown, the power frequency arc cutter consists of a housing 5 and a base 34. The housing 5 is fitted into the base 34, which is connected to the angle connector 10 via bolts 8 and nuts 9. A hinge 7 then connects the housing 5 to the base 34. When the voltage limiter malfunctions, the housing 5 tilts and falls off, no longer fitting into the base 34. The housing 5 then rotates around the hinge 7, lengthening the first protective gap 1, which is longer than the second air gap 28 formed by the upper discharge electrode 25 and the secondary discharge electrode 27. The sheath 4 is made of soft insulating material with a certain gap, ensuring it does not affect the rotation of the hinge 7. The housing 5 rotates around the hinge 7 without falling off, preventing it from hitting other equipment or falling and causing personal injury. Example 2

[0025] The insulating rod 22 is equipped with a secondary protection gap voltage limiter. Its upper end is fixedly connected to the conductor mounting base 23, and its lower end is fixedly connected to the steel foot 14. The upper part of the insulating rod 22 is covered with a first silicone rubber sheath 18 of a first umbrella skirt 20. Between the upper part of the insulating rod 22 and the first silicone rubber sheath 18, there are multiple annular zinc oxide resistance plates 19 and annular electrodes 17 from top to bottom. The annular electrodes 17 are connected to the upper discharge electrode 25 via a conductor 24. The conductor 24 and the upper discharge electrode 25 are covered with a second silicone rubber sheath 26. The lower part of the insulating rod 22 is covered with a third silicone rubber sheath 15 of a second umbrella skirt 16. One side of the angled connector 10 has a connecting flange at its lower end, which is fitted onto the steel foot 14 via a U-shaped clamp 13. Two nuts 11 are used to fasten the connector 10 to the side of the steel foot 14. The other side of the angled connector 10 has a bolt hole in the middle. The angled connector 10 is made of conductive material, and its top has a secondary discharge electrode 27. Power frequency arc cutoff... The device consists of a housing 5 and a first base 34. The housing 5 is fitted into the first base 34. The first base 34 is connected to the angle connector 10 by bolts 8 and nuts 9. The housing 5 is then connected to the first base 34 by a hinge 7. When the pressure limiter malfunctions, the housing 5 tilts and falls off, no longer fitting into the first base 34. The housing 5 then rotates around the hinge 7. The upper end of the spring 29 inside the housing 5 is connected to the second base 3. The second base 3 is connected to the lower discharge electrode 2. The lower end of the spring 29 is connected to the heating resistor 30 at the upper end of the nail gun 32. The lower end of the heating resistor 30 is connected to the nail gun 32. In extreme cases, the heating resistor 30 continuously generates heat, detonating the nail gun. In the product design, the nail gun 32 is located in the upper hole of the bolt 8. A first air gap 1 is formed between the upper discharge electrode 25 and the lower discharge electrode 2. A second air gap 28 is formed between the secondary discharge electrode 27 and the upper discharge electrode 25. The housing 5 and the lower discharge electrode 2 are covered by an outer sheath 4.

[0026] The upper end of the insulating rod 22 is fixedly connected to the conductor mounting base 23, and the lower end is fixedly connected to the steel foot 14. The upper part of the insulating rod 22 is wrapped with a first silicone rubber sheath 18 and a first umbrella skirt 20. Between the upper part of the insulating rod 22 and the first silicone rubber sheath 18, there are multiple annular zinc oxide resistance plates 19 and annular electrodes 17 from top to bottom. The annular electrodes 17 are connected to the upper discharge electrode 25 through a conductor 24. The conductor 24 and the upper discharge electrode 25 are wrapped with a second silicone rubber sheath 26. The lower part of the insulating rod 22 is wrapped with a third silicone rubber sheath 15 and a second umbrella skirt 16. One side of the angle connector 10 has a connecting flange at the lower end, which is fitted onto the steel foot 14 through a U-shaped clamp 13. The connector 10 is fastened to the side of the steel foot 14 with two nuts 11. There is a bolt hole in the middle of the other side of the angle connector 10. The angle connector 10 is made of conductive material. The top of the angle connector 10 has a secondary discharge electrode 27. The cutter consists of a housing 5 and a first base 34. The housing 5 is fitted into the first base 34. The first base 34 is connected to the angle connector 10 by bolts 8 and nuts 9. The housing 5 is then connected to the first base 34 by a hinge 7. When the pressure limiter fails, the housing 5 tilts and falls off, no longer fitting into the base 34. The housing 5 rotates around the hinge 7. The upper end of the spring 29 inside the housing 5 is connected to the second base 3. The lower end of the spring 29 is connected to the heating resistor 30 at the upper end of the nail gun cartridge 32. The lower end of the heating resistor 30 is connected to the nail gun cartridge 32. In extreme cases, the heating resistor 30 continuously generates heat, detonating the nail gun cartridge. In the product design, the nail gun cartridge 32 is located in the upper hole of the bolt 8. A first air gap 1 is formed between the upper discharge electrode 25 and the lower discharge electrode 2. A second air gap 28 is formed between the secondary discharge electrode 27 and the upper discharge electrode 25. The housing 5 and the lower discharge electrode 2 are covered by an outer sheath 4.

[0027] The connection between the housing and the base 34 is sealed with one-component silicone rubber.

[0028] The distance of the second air gap 28 is not less than 90mm, and the distance of the first air gap 1 is between 85-30mm.

[0029] Its principle is as follows: Lightning energy passes through the first protective gap 1—lower discharge electrode 2—base 3—spring 29—heating resistor 30—nailing gun 32—mounting bolt 8—connecting seat 10—steel foot 14—mounting bolt 12—tower mounting seat—earth.

[0030] When the annular zinc oxide resistor 19 is damaged, the first air gap 1 cannot cut off the power frequency arc. The power frequency current flows through the heating resistor 30, causing the heating resistor to continuously generate heat and detonate the nail gun. In the product design, the strength of the outer shell 5 is greater than the connection strength with the base 34. The power frequency arc cutter explodes from the connection point, and the impact force reaches the lower electrode 2 and the shell 5. The sheath 4 rotates and falls off along the hinge 7. After the tilted power frequency arc cutter falls off, the first protective gap 1 is elongated, and its length is greater than the second air gap 28 formed by the upper discharge electrode 25 and the secondary discharge electrode 27. The length of the second air gap 28 is not less than 90mm. The second protective gap 28 is still effective, and the power line still has lightning protection and voltage limiting functions.

[0031] After the power frequency arc cutter detaches, it is convenient for maintenance personnel to observe it.

[0032] The outer sheath 4 of the power frequency arc cutter can be distinguished by different colors to differentiate the phase sequence of the power line.

[0033] The lower or upper ends of the umbrella skirt 21 can be reinforced with ribs to increase its resistance to the weight of accumulated ice and snow. The diameter of the umbrella skirt 21 is larger than that of the umbrella skirt 20 and the umbrella skirt 16. In snowy weather, the umbrella skirt 20 and the umbrella skirt 16 will accumulate less snow. When the snow and ice melt, the umbrella skirt will prevent the umbrella skirt 20 and the umbrella skirt 16 from bridging.

[0034] like Figure 2 As shown, the power frequency arc cutter consists of a housing 5 and a base 34. The housing 5 is fitted into the base 34, which is connected to the angle connector 10 via bolts 8 and nuts 9. A hinge 7 then connects the housing 5 to the base 34. When the pressure limiter malfunctions, the housing 5 tilts and falls off, no longer fitting into the base 34. The housing 5 then rotates around the hinge 7. When the pressure limiter malfunctions again and detonates the nail gun 32, the housing 5 falls off and rotates around the hinge 7, lengthening the first protective gap 1, which is greater than the second air gap 28 formed by the upper discharge electrode 25 and the secondary discharge electrode 27. The sheath 4 is made of soft insulating material with a certain gap, ensuring it does not affect the rotation of the hinge 7. The housing 5 rotates around the hinge 7 without falling off, preventing it from hitting other equipment or causing injury to personnel.

Claims

1. A voltage limiter with secondary protection gap, characterized in that, The upper end of the insulating rod (22) is fixedly connected to the conductor mounting base (23), and the lower end is fixedly connected to the steel foot (14). The upper part of the insulating rod is wrapped with the first silicone rubber sheath (18) of the first umbrella skirt (20). Between the upper part of the insulating rod and the first silicone rubber sheath (18), there are multiple annular zinc oxide resistor sheets (19) and an annular electrode (17) from top to bottom. The annular electrode is connected to the upper discharge electrode (25) through the conductor (24). The conductor and the upper discharge electrode are wrapped with the second silicone rubber sheath (26). The lower part of the insulating rod is wrapped with the third silicone rubber sheath (15) of the second umbrella skirt (16). The lower end of one side of the angle connector (10) has a connecting flange that is fitted onto the steel foot (14) through a U-shaped clamp (13). Two nuts are used to fasten one side of the angle connector to the steel foot. There is a bolt hole in the middle of the other side of the angle connector. The angle connector is made of conductive material. The top of the angle connector has a secondary discharge electrode (27). The arc cutter consists of a housing (5) and a first base (34). The housing is embedded with the first base. The first base is connected to the angle connector by bolts (8) and nuts (9). The hinge (7) connects the housing to the first base. When the pressure limiter fails, the housing tilts and falls off and is no longer embedded with the first base. The housing rotates around the hinge. The upper end of the hot melt (6) inside the housing is fixedly connected to the second base (3) at the upper end of the housing. The second base is connected to the lower discharge electrode (2). The lower end of the hot melt is fixedly connected to the bolt (8). The hot melt and the second base are tightly pulled onto the angle connector by the bolts (8) and nuts (9). A first air gap (1) is formed between the upper discharge electrode (25) and the lower discharge electrode (2). A second air gap (28) is formed between the secondary discharge electrode (27) and the upper discharge electrode (25). The second air gap is larger than the first air gap. The housing (5) and the lower discharge electrode (2) are covered with an outer sheath (4).

2. A voltage limiter with secondary protection gap, characterized in that, The upper end of the insulating rod (22) is fixedly connected to the wire mounting base (23), and the lower end is fixedly connected to the steel foot (14). The upper part of the insulating rod is covered with the first silicone rubber sheath (18) of the first umbrella skirt (20). Between the upper part of the insulating rod and the first silicone rubber sheath (18), there are multiple annular zinc oxide resistor sheets (19) and an annular electrode (17) from top to bottom. The annular electrode is connected to the upper discharge electrode (25) through the conductor (24). The conductor and the upper discharge electrode are covered with the second silicone rubber sheath (26). The lower part of the insulating rod is wrapped with the third silicone rubber sheath (15) of the second umbrella skirt (16). The lower end of one side of the angle connector (10) has a connecting flange that is connected to the steel foot (14) by a U-shaped clamp (13). Two nuts are used to fasten one side of the angle connector to the steel foot. There is a bolt hole in the middle of the other side of the angle connector. The angle connector is made of conductive material. The top of the angle connector has a secondary discharge electrode (27). The power frequency arc cutter consists of a housing (5) and a first base ( 34) Composition: The shell is fitted with the first base. The connection between the shell and the first base is sealed with single-component silicone rubber. The first base is connected to the angle connector by bolts (8) and nuts (9). The hinge (7) connects the shell to the first base. When the pressure limiter fails, the shell tilts and falls off, no longer fitting with the first base. The shell rotates around the hinge. The upper end of the spring (29) inside the shell (5) is connected to the second base (3). The second base is connected to the lower discharge electrode (2). The lower end of the spring is connected to the heating element. The upper end of the resistor (30) is connected, and the lower end of the heating resistor is connected to the upper end of the nail gun (32). In extreme cases, the heating resistor continuously generates heat and detonates the nail gun. The nail gun is located in the upper hole of the bolt (8). A first air gap (1) is formed between the upper discharge electrode (25) and the lower discharge electrode (2). A second air gap (28) is formed between the secondary discharge electrode and the upper discharge electrode (25). The second air gap is larger than the first air gap. The outer casing and the lower discharge electrode are covered with an outer sheath (4).

3. The pressure limiter with secondary protection gap according to claim 1, characterized in that, The power line voltage is 10-500KV, the second air gap is 90-4300mm, and the first air gap is between 30-2300mm.

4. The pressure limiter with secondary protection gap according to claim 3, characterized in that, When the power line voltage is 10kV, and four annular zinc oxide resistors (19) are used, each with a thickness of 24mm, and the first air gap is 30-80mm, the 10kV power line operating voltage is jointly borne by the four zinc oxide resistors and the first air gap in series. When the zinc oxide resistors are damaged or their seals are damaged, the resistance of the zinc oxide resistors drops significantly, and the first air gap cannot bear the 10kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap and activate the second air gap. The distance of the second air gap is 95-160mm. The second air gap can bear the 10kV power line operating voltage on its own, and the lightning impulse discharge voltage does not exceed 160kV.

5. The pressure limiter with secondary protection gap according to claim 3, characterized in that, When the power line voltage is 10kV, three annular zinc oxide resistors (19) are used, each with a thickness of 24mm. The first air gap is 50-100mm. During normal operation, the three zinc oxide resistors and the first air gap in series jointly bear the 10kV power line operating voltage. When the zinc oxide resistor is damaged or its seal is damaged, the resistance of the zinc oxide resistor drops significantly, and the first air gap cannot bear the 10kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap and activate the second air gap. The distance of the second air gap is 95-160mm. The second air gap can bear the 10kV power line operating voltage on its own, and the lightning impulse discharge voltage does not exceed 160kV.

6. The pressure limiter with secondary protection gap according to claim 3, characterized in that, When the power line voltage is 35kV, and 11-15 ring zinc oxide resistors (19) are used, the thickness of each piece is 24mm. The first air gap is 150-260mm. During normal operation, the zinc oxide resistors and the first air gap in series jointly bear the 35kV power line operating voltage. When the zinc oxide resistors are damaged or their seals are damaged, the resistance of the zinc oxide resistors drops significantly, and the first air gap cannot bear the 35kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap and activate the second air gap. The distance of the second air gap is 290-480mm. The second air gap can bear the 35kV power line operating voltage on its own, and the lightning impulse discharge voltage does not exceed 350kV.

7. The pressure limiter with secondary protection gap according to claim 3, characterized in that, When the power line voltage is 110kV, and 26-36 ring zinc oxide resistors (19) are used, the thickness of each piece is 24mm. The first air gap is 350-650mm. During normal operation, the zinc oxide resistors and the first air gap in series jointly bear the 110kV power line operating voltage. When the zinc oxide resistors are damaged or their seals are damaged, the resistance of the zinc oxide resistors drops significantly, and the first air gap cannot bear the 110kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap and activate the second air gap. The distance of the second air gap is 700-1200mm. The second air gap can bear the 110kV power line operating voltage on its own, and the lightning impulse discharge voltage does not exceed 690kV.

8. The pressure limiter with secondary protection gap according to claim 3, characterized in that, When the power line voltage is 220kV, and 50-70 ring zinc oxide resistors (19) are used, the thickness of each piece is 24mm. The first air gap is 600-1100mm. During normal operation, the zinc oxide resistors and the first air gap in series jointly bear the 110kV power line operating voltage. When the zinc oxide resistors are damaged or their seals are damaged, the resistance of the zinc oxide resistors drops significantly, and the first air gap cannot bear the 220kV power line operating voltage. The power frequency arc cutter is activated to cut off the first air gap and activate the second air gap. The distance of the second air gap is 1300-2100mm. The second air gap can bear the 220kV power line operating voltage on its own, and the lightning impulse discharge voltage does not exceed 1200kV.

9. The pressure limiter with secondary protection gap according to claim 3, characterized in that, When the power line voltage is 500kV, and 100-140 pieces of annular zinc oxide resistor sheet (19) are taken, the thickness of each piece is: The first air gap is 1400-2300mm, with a diameter of 22.5mm. Under normal operation, the zinc oxide resistor and the first air gap in series jointly bear the operating voltage of the 500kV power line. When the zinc oxide resistor is damaged or its seal is damaged, the resistance of the zinc oxide resistor drops significantly, and the first air gap can no longer bear the operating voltage of the 500kV power line. The power frequency arc cutter is activated to cut off the first air gap and activate the second air gap. The distance of the second air gap is 2100-4300mm. The second air gap can bear the operating voltage of the 500kV power line on its own, and the lightning impulse discharge voltage does not exceed 2100kV.

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