Development of A Vertical Wire Clamp Mechanism and Wiring Device

. With the improvement of social productivity, high-quality power supply is the main requirement for the power industry. To ensure the stability of power supply, power supply companies need to regularly maintain and repair power equipment, during which the use of grounding wire devices is necessary to protect the working process of maintenance personnel. The existing TV, lightning arrester, and circuit isolation switches of 110kV and above grades in substations mostly use the vertical wire connection method to connect with the equipment. During equipment maintenance, there is a risk of virtual connection and dropping when maintenance personnel install grounding wires on such wires, which threatens the safety of the power grid and personnel. To ensure smooth and stable substation equipment maintenance, a vertical wire clamp mechanism and wiring device have been developed, which not only improves the efficiency of maintenance operations and reduces the labor intensity of maintenance personnel but also reduces the work risks during maintenance operations, and is worth promoting in the industry.


Introduction:
The existing TV, lightning arrester, and circuit isolation switches of 110kV and above grades in substations mostly use the vertical wire connection method to connect with the equipment [1].Using existing grounding devices on vertical wires often takes a lot of time to connect the grounding wire, and it is still difficult to install [2][3][4].Even if it is successfully installed, the contact area between the grounding wire and the vertical wire cannot be firmly secured, making it prone to detachment, which poses a serious risk of electric shock to maintenance personnel [5].When maintenance personnel loosen the equipment clamp at the bottom of the vertical wire, the bottom of the vertical wire is no longer fixed, and the grounding wire is very easy to drop.At this time, an elevating vehicle or ladder is required to install the grounding wire, which poses a risk of electric shock and can easily cause safety accidents [6].

Demand Analysis
Researchers conducted on-site investigations and field tests in 85 110kV and above substations of a power supply company in a certain city.It was found that 52 of them adopted the vertical wiring method, and the vertical wiring method was present in every non-GIS equipment 220kV substation.Figure 1 shows the vertical wire connected to the lightning arrester.The vertical wiring method is widely used in various substations, and the insufficient coordination between the grounding wire and the vertical wire is a common problem, which has a wide market demand and an urgent need for solution.

Analysis of the Causes
Researchers conducted on-site tests in substations and compared the stability of the connection between the grounding wire and the vertical wire by observing the connection points, testing the probability of the grounding wire falling off after swinging it over a hundred times, and measuring the force required to remove the grounding wire.The results for the vertical wiring method and the horizontal wiring method are shown in Table 1.The Mean force required to remove the grounding wire (N) Researchers compared the conductivity of the connection between the grounding wire and the vertical wire and the horizontal wire by measuring the loop resistance at the connection points.The results for the vertical wiring method and the horizontal wiring method are shown in  After three measurements, the results were found to be repeatable, proving that the disturbance tolerance and contact resistance of the vertical wiring method with traditional grounding wire connection are inferior to that of the horizontal wiring method.The specific reason is that when the vertical wiring method is used for grounding, the connection point is not secure due to the diagonal connection, resulting in insufficient clamping force and stability, making it prone to detachment.

Risk Analysis
According to the investigation, the existing vertical wiring method is widely used in various substations and has difficulties in reliable compatibility with traditional grounding wires.It exhibits insufficient stability and poor conductivity, which affects the grounding reliability of the equipment.
The power supply company in a certain city has more than 30 major repair and renovation projects, over 200 defect elimination plans, and more than 50 emergency repairs in a year.Over 90% of the maintenance work requires the use of grounding wires.If the contact area of the grounding wire cannot be secured or detaches during equipment maintenance, it poses a great electrical safety threat to the maintenance personnel.When the maintenance personnel disconnect the equipment line clamp at the lower end of the vertical wiring, the lower end of the vertical wiring is no longer secured, making it easy for the grounding wire to detach.In such cases, aerial work platforms or elevating ladders are required to install the grounding wire, which also poses risks of electrical shock and falls from height.Therefore, the development of a vertical wiring clamp mechanism and wiring device will protect maintenance personnel from electrical safety threats and greatly reduce the time for maintenance personnel to install grounding wires on vertical wiring.It will also help reduce safety accidents caused by poor contact of grounding wires in the field.

Determination of Major Factors
An analysis of the unreliable grounding factors is shown in Figure 2.  3 below.

Record and verify the on-site measurements
The difference is greater than 50 micro-ohms G

Confirmation Process
The researchers confirmed the cause according to the cause confirmation plan, and the results are shown in Table 4 below: Excellent Through the theoretical and practical assessment of 15 professionals, it is found that everyone has qualified level in grounding wire installation and safety measures arrangement, and the grounding wire installation will not be unstable because of their own level.

Conlusion
Not the main factor.The results showed that the height had little impact on the reliability of the grounding wire.

Conlusion
Not the main factor.0%(Horizontal connection) 0%(Horizontal connection) The results showed that the position of the primary wire did not have a significant impact on the reliability of the grounding wire.

Conlusion
Not the main factor.1%(Horizontal connection) The results showed that an increasing wind force increased the risk of the vertical wire disconnecting from the grounding wire but did not affect the horizontal wire connections.

Conlusion
Not the main factor.

Design Concept
The main factors causing insufficient disturbance tolerance and high contact resistance [7] in the connection between vertical wiring and traditional grounding wires are determined by researchers to be the inclination in the connection between the grounding wire clamp and the insulating rod and the insufficient clamping force of the grounding wire clamp spring [8].To address these two factors, the researchers propose the following design concepts: 1) To address the issue of alignment between the grounding wire clamp and the insulating rod, the angle between the clamp and the rod can be increased so that the grounding wire can be vertically installed on the vertical wiring equipment, with the contact area between the grounding wire and the vertical wiring equipment accounting for more than 80%.
2) To address the problem of insufficient clamping force of the grounding wire clamp spring, the clamping spring can be replaced with a product with a higher clamping force, ensuring that the circuit resistance between the equipment and the grounding wire is less than 15uΩ when the grounding wire is suspended on the vertical wiring connection device.

Technical Solution
Researchers have designed a vertical wiring clamp mechanism from the following three aspects, as shown in Figure 3.

1) Angle Design:
To solve the problem of alignment between the grounding wire clamp and the insulating rod, researchers have designed a vertical wiring clamp mechanism, including an installation plate and a clamp block.The installation plate has a wire clamp part, a connecting part for connecting with the supporting rod, and a wiring component for connecting the grounding wire.The wire clamp part has a V-shaped surface facing the clamp block, and the installation plate is L-shaped.The wire clamp part is fixed at one end of the installation plate, forming a U-shaped structure with the installation plate to ensure that the connecting part is parallel to the wire clamp part when clamped.A space for the vertical wiring to enter is formed between the clamp block and the wire clamp part.
2) Clamping Design: To solve the problem of insufficient clamping force of the grounding wire clamp spring, researchers have decided to place an elastic component between the clamp block rotating device and the installation plate.The elastic component is a torsion spring set on the rotating pin 1.
When the clamp block rotates downward, it drives the torsion spring to twist, providing elastic energy storage.
After releasing the force that makes the clamp block rotate downward, the clamp block can rotate back under the elastic force of the torsion spring, achieving clamping of the vertical wiring.
3) Overall Design: Figure 3 shows a vertical wiring clamp mechanism that takes into account both the angle design and the clamping design.During use, the grounding wire is connected to the wiring component, the connecting part is connected to the top of the supporting rod, and the vertical wiring clamp mechanism is supported to the position of the vertical wiring through the supporting rod.Then, the pull rope is pulled downward to enlarge the space between the clamp block and the wire clamp part, facilitating the entry of the vertical wiring.Next, the supporting rod is manipulated to allow the vertical wiring to enter the wire clamp space.Finally, the force on the pull rope is released, causing the clamp block to rotate and tightly hold the vertical wiring between the clamp block and the wire clamp part.Conversely, pulling the pull rope downward and removing the vertical wiring clamp mechanism completes the process.

Working Principle
The vertical wiring clamp mechanism shown in Figure 3 includes an installation plate 1 and a clamp block 2. The installation plate 1 has a wire clamp part 3, a connecting part 4 for connection with the supporting rod, and a wiring component 5 for connecting the grounding wire.The clamp block 2 is rotatably arranged on the installation plate 1 and is equipped with an elastic element 6 between the clamp block 2 and the installation plate 1.A wire clamp space 7 is formed between the clamp block 2 and the wire clamp part 3 for the insertion of the vertical wiring 8.The clamp block 2 is connected to a pull rope 9 for rotating the clamp block 2.
During usage, the grounding wire is connected to the wiring component 5, the connecting part 4 is connected to the top of the supporting rod, and the vertical wiring clamp mechanism is supported vertically at the position of the vertical wiring 8 using the supporting rod.Then, the pull rope 9 is pulled downward (the length of the pull rope 9 meets the operating requirements and can be designed longer than the supporting rod) to enlarge the wire clamp space 7 between the clamp block 2 and the wire clamp part 3, facilitating the entry of the vertical wiring 8. Next, the supporting rod is manipulated to allow the vertical wiring 8 to enter the wire clamp space 7, and then the force on the pull rope 9 is released.At this time, the clamp block 2 rotates under the action of the elastic element 6, tightly holding the vertical wiring 8 between the clamp block 2 and the wire clamp part 3. On the contrary, pulling the pull rope 9 downward, and then removing the vertical wiring clamp mechanism completes the process.This vertical wiring clamp mechanism is suitable for grounding the vertical wiring 8, with simple operation, good stability after connection, less chance of falling off, and high safety.

On-site Verification
The clamp mechanism and wiring device were used at a 220kV substation during the complete shutdown and maintenance of the 220kV equipment, as shown in Figure 4.The grounding wire did not fall off during the maintenance process, and the maintenance work was successfully completed.The connection was stable and the contact resistance was low.The results of the field verification are shown in Tables 5 and 6.After adopting this new technology, it not only reduces the workload of maintenance personnel, but also greatly improves the reliability and safety level of grounding during maintenance, ensuring the personal safety of the maintenance personnel.

Conclusion
The new type of clamping mechanism and wiring device designed for grounding connection of vertical conductors ensures reliable and secure installation, avoiding incidents caused by loose grounding wires [9].More importantly, it guarantees the personal safety of maintenance personnel.
The operation and use of this equipment are simple and convenient, eliminating the need for extensive learning costs associated with tool replacement.It improves the efficiency and safety of substation maintenance operations [10] and has high promotional value.

Figure 1 .
Figure 1.Lightning arrester with vertical conductor connection mode

Figure 2 .
Figure 2.An analysis of the unreliable grounding factors Based on the identified end factors, the research team has developed a plan for determining the key factors, as shown in Table3below.

Fig. 3
Fig. 3 Structure diagram of vertical conductor clamping mechanism

Fig. 4
Fig. 4 Site diagram of a 220kV substation product.

Table 2 .
Conductivity of equipment and grounding wire

Table 3 .
Confirmation schedule of major factors

Table 4 .
1 Confirmation table of major factors

Table 4 .
2 Confirmation table of major factors that when the grounding wire clamp is aligned with the insulating pole in a straight line, it can cause poor connection with the vertical wire equipment, incomplete clamping of the wire into the grounding wire clamp, and reduced reliability.

Table 4 .
3 Confirmation table of major factors

Table 4 .
4 Confirmation table of major factorsDuring on-site experiments, the researchers measured the resistance between the vertically connected wire equipment and the grounding wire after clamping using additional springs and rupture springs.The results are shown in the following table:

Table 4 .
5 Confirmation table of major factors

Table 4 .
Increasing the number of clamps did increase the contact area, resulting in a lower loop resistance.However, due to the resistance of the grounding wire and contact resistance, increasing the contact area had little impact on the loop resistance once the clamps were securely connected.
Based on the above table, there are two main factors that contribute to the low efficiency of protective device replacement, as shown in table 4.8 below.

Table 4 .
8 Table of main factors

Table 5 .
Stability of matching between equipment and grounding wire

Table 6 .
Conductivity of equipment and grounding wire