User:This is for writ2e/sandbox/Conductor Clashing

Conductor clashing is a phenomenon when two or more conductors (objects that allow the transmission of charge, such as electrical cables or power lines) come into contact or close proximity, leading to disturbances in the flow of electrical current. This disturbance occurs due to a wide range of environmental conditions, natural events, and human-related behaviors. These conditions lead to the unintended contact of conductors, triggering a complex physical and chemical process. The process begins with the conductor material melting and vaporizing upon contact, creating heat. The heat vaporizes the metal and increases the pressure, transforming the vaporized metal into sparks (high-temperature molten metal particles). These sparks might be carried away by the wind and land on nearby vegetation. Occasionally, these sparks start fires that grow to produce wildfires that cover acres of surrounding areas. These fires can lead to great financial losses and leave significant damage, which is why proper safety measures and protocols are essential to prevent conductor clashing and ensure the safe and efficient distribution of electricity.

Causes

The occurrence of conductor clashing in power systems can be attributed to a variety of factors, including environmental conditions, natural occurrences, and human-related behaviors.

Weather

One significant contributing factor is the influence of environmental conditions, particularly during severe storms or hot weather. Heavy winds or gusts associated with these conditions can often result in the unintended contact of conductors. This situation becomes particularly noticeable in scenarios where power lines exhibit excessive sag or other structural conditions that permit conductors to come into close proximity.

Nature

The presence of trees near power lines is also another factor that leads to conductor clashing. During inclement weather or as a result of natural phenomena, tree branches may break and fall onto the wires, increasing the potential for conductors to clash by bringing them together.

Wildlife

The interaction between wildlife and power lines also plays a role in conductor clashing events. Birds, in particular, can inadvertently cause power lines to sag when they perch, land, or interact with them. Other animals that also walk across power lines, such as squirrels, can also have this effect.

Collisions

Human-related behaviors and accidents represent another set of factors that can lead to conductor clashing. Vehicular collisions with utility poles can result in pole leaning, which in turn may cause power lines to clash. This type of collision, often the result of accidents, can have a cascading effect on the power system, leading to conductor clashing.

Vandalism

Acts of vandalism targeted at power lines introduce another reason for conductor clashing. Deliberate acts of hurling objects at power lines can induce drooping and the subsequent collision of wires.

Process

When conductors clash, a series of complex physical and chemical processes occur, involving intense heat, the vaporization of conductor material, and the expulsion of metal particles.

Heat and Vaporization

When two conductors of a power line clash, intense heat is generated, which can lead to the melting and vaporization of the conductor material. This results in the formation of a high-pressure gas consisting of metal vapor and other byproducts. The pressure within the conductor can become high enough to eject tiny molten metal particles from the point of contact. These ejected particles, often in the form of sparks, are then carried away by the wind.

Combustion

The combustion aspect is driven by the release of energy in the form of an electrical arc (electrical breakdown of gas resulting in electrical discharge). Simultaneously, the conductor material erodes and vaporizes due to the intense heat generated by this arc. The process is significantly influenced by key parameters, including arc voltage, short-circuit current, and the duration of the arc. A higher arc voltage intensifies the energy of the electrical arc, while an increased short-circuit current leads to more substantial heat generation and vaporization of the conductor material. The duration of the arc plays a critical role, impacting the extent of material vaporization and potentially leading to molten or burning particles.

Chemical Reaction

When conductors clash, the arcing event is characterized by a bright flash, the emission of sparks, and a puff of white smoke. The intense heat of the arc causes the underlying metal to reach its boiling point and vaporize. When these vaporized metal particles come into contact with the air, they ignite and burn rapidly, forming ${\ce {Al2O3}}$ (aluminum oxide) as small aerosol particles. These aerosol particles can reach temperatures anywhere from 930 K (Kelvin) to 2730 K and create the characteristic puff of smoke. When the oxide is in a molten state, the oxidation process proceeds rapidly, with the heat generated by oxidation offsetting heat losses through convection and radiation. These droplets will continue to burn until all the metal is consumed or until they reach the ground.

Effects and Consequences

Fire ignition resulting from conductor clashing has been a recurring issue worldwide, with numerous instances occurring in various countries. Such incidents can lead to significant environmental damage, such as forest fires, as well as substantial financial losses and, in some cases, pose potential threats to human lives.

An example of a conductor clashing catastrophe occurred in Western Australia on December 2nd, 2004. A 19.1 kV (kilovolt) conductor became dislodged from a pole-mounted insulator at the first pole and subsequently clashed with the underslung running earth conductor approximately 200 meters away. This collision led to a flashover (ignition of combustible material in an enclosed area), releasing hot metal particles (sparks) that ignited dry harvested stubble, which initiated the wildfire. Amid the fire, both conductors snapped, with the first conductor ultimately succumbing to structural wear and the influence of northerly winds. When both conductors fell and made contact with the dividing fence, the wildfire was ignited. It's worth noting that the property owner had previously reported a low-hanging power line conductor adjacent to the first pole. According to the property owner's estimate, roughly 468 hectares of land had been burned.

Experiments and Results

This section outlines an experiment looking into particle generation in terms of size, number, and behavior. This experiment aims to provide insight about the phenomenon and help find solutions to create protocols to maintain safety when conductor clashing occurs.

Experiment

These three scenarios were examined:

• 100A-rated fuse that met overload criteria

• 125A-rated fuse at the limit

• 160A-rated fuse that did not meet overload criteria.

Line-to-line short-circuit current equation:

${\rm {I}}_{{\rm {K}}2}^{\prime \prime }={{{\rm {c}}\cdot {\rm {U}}_{\rm {n}}} \over {{\rm {Z}}_{(1)}+{\rm {Z}}_{(2)}}}={{{\rm {c}}\cdot {\rm {U}}_{\rm {n}}} \over {2{\rm {Z}}_{(1)}}}$

Where

${\rm {Z}}_{(1)},{\rm {Z}}_{(2)}$ are positive and negative sequences of short circuit impedance (a measure of opposition that a circuit offers to the flow of alternating current) in the subtransient period.

${\rm {U}}_{\rm {n}}$ is nominal system voltage(standard voltage level for a system)

c is voltage factor (difference between nominal voltage and actual voltage)

Using this equation, the line-to-line current was calculated to be 1700 amperes. This is the measure of the electric current that flows through the conductors when they come into contact. This current is significant because it determines the behavior of the conductor clashing event, including the generation of sparks and the effectiveness of fuses in protecting the system. In this case, the line-to-line short circuit current of 1700A was used for testing different fuse rated currents and assessing the protection tripping times in response to conductor clashing. The simulation and analysis helped determine the adequacy of the fuses in different scenarios, with variations in fuse rated current.

The following tables show the number of particles, means of particle diameters, standard deviations, and coefficients of skewness (a measure of the distribution's shape). These were obtained in a live network and a laboratory under different fuse rated currents.

Live Network

Fuse rated current [A]	100	125	160
Number of Particles	184	544	1100
mean (mm)	0.582	0.698	0.852
standard deviation	0.225	0.256	0.334
skewness	1.519	1.036	0.378

Laboratory

Fuse rated current [A]	100	125	160
Number of Particles	57	156	256
mean (mm)	0.675	0.678	0.732
standard deviation	0.274	0.239	0.320
skewness	0.919	0.957	1.117

Results

This study first calculates the line-to-line short-circuit current, finding it to be 1700A. It then examines the relationship between fuse ratings (the current carrying capacity of the fuses) and protection tripping times, noting a correlation between manufacturer catalog data and the cessation of spark generation during experiments. The analysis further investigates particles generated during conductor clashing experiments conducted in both real networks and a lab setting. The descriptive statistics, like mean diameter and skewness, revealed that mean particle size increased with higher fuse ratings in the live network, while skewness coefficients decreased. On the other hand, there was an inverse relationship between the lab fuse ratings and the skewness coefficient, where higher fuse ratings led to higher skewness coefficients. The average mean rises from 0.582 to 0.852 mm in the live network and only from 0.675 to 0.732 mm in the laboratory, highlighting the differences in results between the live network and laboratory setting.

Analyzing descriptive statistics, such as mean particle diameters and skewness coefficients, reveals the variations associated with different fuse ratings. These findings are derived from the study of particles generated during conductor clashing experiments in both actual network scenarios and controlled laboratory settings. The insights gained through this study regarding conductor clashing events and their parameters can contribute to improved electrical system protection and reliability in the future.

Prevention and Safety

Proper safety measures and protocols are essential to prevent future conductor clashing incidents and ensure the safe and efficient distribution of electricity.

Copper Conductors

The enhancement of existing aluminum lines with copper conductors presents a notable boost in performance. While copper conductors offer a superior solution, they come at a slightly higher cost. However, the need for more support structures for conductors guarantees heightened safety and durability.

Conductor Spacing

Increasing conductor spacing reduces the risk of the conductors clashing with each other since the distance between them is greater. Isolating the conductors not only improves safety but also promotes a more organized and efficient distribution system.

Alloyed Aluminum Conductor

Developing an alloyed aluminum conductor with reduced ignition potential represents an innovative and cost-effective solution. This alloyed conductor has the potential to eject safe, low-temperature droplets, ensuring safer operation without compromising on expenses.

Aerial Bundled Conductor (ABC)

Upgrading existing aluminum lines with ABC or aerial bundled conductors (overhead power lines using several insulated conductors) offers a comprehensive solution to the conductor clashing issue. This approach eliminates the potential for conductor clashing because each conductor has its own insulating sheath (protective covering).