Stray current drain device in a pipeline cathodic protection system
Patent Information
- Application Number
- CN202522295774.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-10-30
- Estimated Expiration
- 2035-10-30
AI Technical Summary
[0007]实用新型目的：为解决现有交流排流装置在强交流干扰下的排流效果不佳且抗电冲击性能差的问题，本实用新型提出了一种管道阴极保护系统中的杂散电流排流装置，根据埋地燃气管道的特点及现有的牺牲阳极阴极保护方式，采用接地排流与极性排流相结合的方式进行排流，即在排流方案中，使用原有牺牲阳极作为接地极，然后在牺牲阳极和管道之间加装极性排流装置，防止杂散电流通过牺牲阳极流入管道
（1）本实用新型阻挡了逆向电流流入镁包，减少了镁包的损耗；
Smart Images
Figure CN224917911U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of automatic elimination of stray current in the reverse direction, specifically a stray current drainage device in a pipeline cathodic protection system. Background Technology
[0002] Stray current refers to current flowing along a path other than the prescribed path; it is also known as "stray current." Stray current flows into a pipe from one part and out from another, causing a change in the current density on the pipe surface, which is called interference. It manifests as a change in the pipe-to-ground potential.
[0003] DC tram systems often use the rails as a current loop. If the rails are poorly insulated from the soil, current will flow into the soil. If there are buried pipes near the rails, this current may enter those pipes, becoming stray current. Figure 1 As shown, the magnitude and direction of stray currents entering the pipe change as the DC tram moves.
[0004] When a subway accelerates, the potential of nearby buried pipelines becomes negative relative to the subway track potential, causing stray currents to flow from the subway tracks, through the soil, and into the pipelines. When the subway decelerates, this process reverses. Sacrificial anodes are a common measure to mitigate this stray current interference, but when stray currents flow into the sacrificial anode, it can cause polarization reactions on the anode surface, leading to decreased anode efficiency and potentially accelerating pipeline corrosion.
[0005] Existing technologies primarily rely on sacrificial anodes to mitigate the impact of stray currents on buried pipelines. When stray currents in subways are excessive, they can enter the pipeline through the sacrificial anode, which not only reduces the lifespan of the sacrificial anode but may also exacerbate corrosion at pipeline breakage points.
[0006] Currently, there are two main types of AC drainage devices in use. The first is a solid-state decoupler, which can conduct AC current and provide protection when the pipeline voltage is too high. However, due to its long grounding electrode, the grounding resistance is easily affected by the operating environment, resulting in poor drainage performance. The second type is a clamping drainage device, installed between the pipeline and the drainage ground bed. Stray current is discharged through the drainage ground bed, which can effectively reduce the AC voltage on the pipeline. However, this type of drainage device has strict limitations on the grounding material, which must be consistent with the pipeline material. Moreover, this device has poor drainage performance under strong AC interference and poor resistance to electric shock. For AC drainage devices, issues such as grounding resistance and grounding materials urgently need to be addressed. Furthermore, AC drainage devices should be further improved and designed in accordance with the operating environment. Summary of the Invention
[0007] Purpose of the utility model: To solve the problem that existing AC drainage devices have poor drainage effect and poor resistance to electric shock under strong AC interference, this utility model proposes a stray current drainage device in a pipeline cathodic protection system. Based on the characteristics of buried gas pipelines and the existing sacrificial anode cathodic protection method, a combination of grounding drainage and polarity drainage is adopted for drainage. That is, in the drainage scheme, the original sacrificial anode is used as the grounding electrode, and then a polarity drainage device is installed between the sacrificial anode and the pipeline to prevent stray current from flowing into the pipeline through the sacrificial anode.
[0008] Technical solution: A stray current drainage device in a pipeline cathodic protection system, comprising: a type A diode and a type B diode; The type A diode includes a first diode and a first resettable fuse; one end of the first resettable fuse is connected to the negative terminal of the first diode, the positive terminal of the first diode is connected to the type B diode, and the other end of the first resettable fuse is connected to a magnesium-clad wire. The type B diode includes a second diode and a second resettable fuse; the positive terminal of the second diode is connected to a pipe, the negative terminal of the second diode is connected to one end of the second resettable fuse, and the other end of the second resettable fuse is connected to the positive terminal of the first diode in the type A diode.
[0009] Furthermore, both the first diode and the second diode are Schottky diodes.
[0010] Furthermore, the type A diode also includes a first female connector and a first male connector; one end of the first female connector is connected to the other end of the first resettable fuse, and the other end of the first female connector is connected to a reserved connector; one end of the first male connector is connected to the positive terminal of the first diode, and the other end of the first male connector is connected to the main unit box connector. The B-type diode also includes a second female connector, a second male connector, and a wire. One end of the second female connector is connected to the positive terminal of the second diode, and one end of the second female connector is connected to one end of the second male connector via a wire. The other end of the second female connector is connected to a reserved connector. One end of the second male connector is connected to the other end of the second resettable fuse, and the other end of the second male connector is connected to the main unit box connector.
[0011] Furthermore, the reserved connector includes a magnesium-coated wire connector, a pipe connector, and a polarization probe; the other end of the first mating female is connected to the magnesium-coated wire connector of the reserved connector, and the other end of the second mating female is connected to the pipe connector and the polarization probe of the reserved connector. The main unit connector includes a magnesium-coated wire connector, a pipe connector, and a polarization probe; the other end of the first male connector is connected to the magnesium-coated wire connector of the main unit connector, and the other end of the second male connector is connected to the pipe connector and the polarization probe of the main unit connector.
[0012] Furthermore, the polarization probe includes a polarization black wire, and the other end of the second female connector is connected to the pipe joint of the reserved connector and the polarization black wire; the other end of the second male connector is connected to the pipe joint of the main unit box connector and the polarization black wire.
[0013] Beneficial effects: Compared with the prior art, this utility model has the following advantages: (1) This utility model blocks the reverse current from flowing into the magnesium pack, thus reducing the loss of the magnesium pack; (2) This utility model has a simple structure, is easy to install, and has high drainage efficiency; (3) The self-resetting fuse used in this utility model prevents excessive current in the soil from damaging the equipment and effectively protects the on-site monitoring equipment. Attached Figure Description
[0014] Figure 1 A schematic diagram illustrating the formation of stray currents in a DC tram system; Figure 2 This is a schematic diagram of the drainage device proposed in this utility model; Figure 3 This is a schematic diagram of the drainage device proposed in this utility model; Figure 4 This is a connection diagram of the drainage device proposed in this utility model. Detailed Implementation
[0015] The technical solution proposed by this utility model will now be further described in conjunction with the embodiments and the accompanying drawings.
[0016] like Figure 2As shown in this embodiment, a stray current drainage device in a pipeline cathodic protection system mainly includes: a type A diode and a type B diode. The type A diode is used to connect to two magnesium-coated wires, and the type B diode is used to connect to the pipeline and the polarization black wire of the polarization probe. Specifically, the type A diode includes a female connector 1, a male connector 2, a diode 3, and a resettable fuse 4. In the type A diode, one end of the female connector 1 is connected to one end of the male connector 2 in sequence through the resettable fuse 4 and the negative terminal of the diode 3. The other end of the female connector 1 is connected to the male connector pre-installed on site to connect to the two magnesium-coated wires, and the other end of the male connector 2 is connected to the female connector pre-installed on site. The B-type diode includes a female connector 1, a male connector 2, a diode 3, a resettable fuse 4, and a wire 5. In the B-type diode, one end of the female connector 1 is connected to one end of the male connector 2 in sequence through the positive terminal of the diode 3 and the resettable fuse 4. One end of the female connector 1 is also connected to one end of the male connector 2 through the wire 5. The other end of the female connector 1 is connected to a pipe, and the other end of the male connector 2 is connected to the A-type diode through the main unit box connector, thereby achieving connection with the magnesium-clad diode.
[0017] In this embodiment, diode 3 is used to achieve unidirectional current conduction, allowing current to flow only from the pipe to the magnesium anode. The resettable fuse 4 is composed of specially treated polymer resin and conductive particles distributed within it, and is a common type of resettable fuse. When the stray current drainage device proposed in this embodiment is connected between the reserved connector in the field and the main measuring unit box connector, due to the unidirectional conduction of diode 3, the anode current can only flow from the pipe to the magnesium anode, and the resettable fuse 4 prevents large currents from breaking down the diode. The diode used in this embodiment is a Schottky diode.
[0018] like Figure 4 As shown, without the stray current drainage device provided in this embodiment, the magnesium foil and the pipe are directly connected. Therefore, the stray current drainage device provided in this embodiment is added to the connection line between the two. Thus, the polarization black wire in the field and the polarization black wire in the main unit are connected by a wire. After the polarization probe is installed in the field, three wires—red, black, and blue—will be led out from the polarization probe, and these three wires need to be connected to the main unit.
[0019] When a short circuit or overload occurs in the circuit, the large current flowing through the resettable fuse generates heat that melts the polymer resin, causing it to rapidly expand in volume and form a high-resistance state. This rapidly reduces the operating current, thus limiting and protecting the circuit. Once the fault is cleared, the resettable fuse recrystallizes, shrinks in volume, and the conductive particles reform a conductive path, restoring the fuse to a low-resistance state, thus completing the circuit protection without requiring manual replacement.
[0020] The stray current drainage device proposed in this embodiment forms a unidirectional polarity drain in the drainage line, allowing stray current to flow only from the pipe to the interference source, while the interference source current cannot flow into the pipe in the opposite direction. This device has a simple structure, is easy to install, has high drainage efficiency, and remains applicable even when the polarity of the interference potential fluctuates alternately.
[0021] This embodiment employs a combination of grounding drainage and polarity drainage. For grounding drainage, the magnesium sheath serves as a grounding electrode with good contact with the earth, drawing stray current from the pipe down and allowing it to seep into the earth through the grounding electrode, eventually dissipating. For polarity drainage, a "one-way conduction device" controls the current flow, allowing stray current to flow only from the pipe to the grounding electrode (or earth), strictly prohibiting current from flowing back into the pipe. The core of this technique is "restricting direction" to prevent reverse current from damaging the system. The unidirectional conduction characteristic of the diode in the drainage device does not affect this current flow direction (pipe-drainage device-magnesium sheath-earth), but it will prevent reverse stray current from flowing from "earth-magnesium sheath-drainage device-pipe." This achieves both grounding drainage and polarity drainage simultaneously.
Claims
1. A stray current drainage device in a pipeline cathodic protection system, characterized in that: include: Type A diodes and Type B diodes; The type A diode includes a first diode and a first resettable fuse; one end of the first resettable fuse is connected to the negative terminal of the first diode, the positive terminal of the first diode is connected to the type B diode, and the other end of the first resettable fuse is connected to a magnesium-clad wire. The type B diode includes a second diode and a second resettable fuse; the positive terminal of the second diode is connected to a pipe, the negative terminal of the second diode is connected to one end of the second resettable fuse, and the other end of the second resettable fuse is connected to the positive terminal of the first diode in the type A diode.
2. The stray current drainage device in a pipeline cathodic protection system according to claim 1, characterized in that: Both the first diode and the second diode are Schottky diodes.
3. The stray current drainage device in a pipeline cathodic protection system according to claim 1, characterized in that: The type A diode also includes a first female connector and a first male connector; one end of the first female connector is connected to the other end of the first resettable fuse, and the other end of the first female connector is connected to a reserved connector; one end of the first male connector is connected to the positive terminal of the first diode, and the other end of the first male connector is connected to the main unit box connector. The B-type diode also includes a second female connector, a second male connector, and a wire. One end of the second female connector is connected to the positive terminal of the second diode, and one end of the second female connector is connected to one end of the second male connector via a wire. The other end of the second female connector is connected to a reserved connector. One end of the second male connector is connected to the other end of the second resettable fuse, and the other end of the second male connector is connected to the main unit box connector.
4. A stray current drainage device in a pipeline cathodic protection system according to claim 3, characterized in that: The reserved connector includes a magnesium-coated wire connector, a pipe connector, and a polarization probe; the other end of the first female connector is connected to the magnesium-coated wire connector of the reserved connector, and the other end of the second female connector is connected to the pipe connector and the polarization probe of the reserved connector. The main unit connector includes a magnesium-coated wire connector, a pipe connector, and a polarization probe; the other end of the first male connector is connected to the magnesium-coated wire connector of the main unit connector, and the other end of the second male connector is connected to the pipe connector and the polarization probe of the main unit connector.
5. A stray current drainage device in a pipeline cathodic protection system according to claim 4, characterized in that: The polarization probe includes a polarization black wire, and the other end of the second female connector is connected to the pipe joint of the reserved connector and the polarization black wire; the other end of the second male connector is connected to the pipe joint of the main unit box connector and the polarization black wire.