Electrical Corona Losses in Transmission Line | Electrical Corona Effect in Transmission Lines

Summary

The script delves into the phenomenon of Corona discharge in high-voltage transmission lines, where ionized air causes a luminous glow and hissing noise. It discusses the factors influencing Corona, its impact on energy loss, and methods to mitigate it, including the use of Corona rings and optimizing conductor design. The summary also touches on the effects of weather conditions like fog on power transmission and the challenges it poses to equipment maintenance and efficiency.

Takeaways

• 🌐 The phenomenon known as Corona discharge occurs when the electrostatic field around high voltage transmission lines ionizes the surrounding air, causing the conductors to glow and produce a hissing noise.
• 🔌 Corona effect is observed when the potential gradient at the conductor surface reaches 30 kV/cm, leading to air ionization and the creation of a virtual conductor that emits light and sound.
• 💡 Corona Rings, also known as grading rings or anti-corona rings, are devices installed on transmission lines to control electric field distribution and mitigate the corona effect, improving transmission efficiency.
• 🛠️ The primary purpose of Corona Rings is to modify the electric field around conductors, reducing the electric field intensity at critical points and minimizing the likelihood of corona discharge.
• 🔍 Corona loss is a type of power loss in transmission lines caused by the ionization of air molecules near the conductors, which carries current and results in energy dissipation as heat and light.
• 📉 Factors affecting the corona phenomenon include conductor size, surface condition, spacing between conductors, supply voltage, and atmospheric conditions.
• 🔧 Methods for reducing Corona losses include using larger diameter conductors, increasing conductor spacing, installing Corona Rings, improving insulator performance, and optimizing transmission line routing.
• 🛡️ Corona discharge can have both advantages and disadvantages; it can limit voltage surges and reduce audible noise from wind-induced conductor vibrations, but it also leads to energy losses, insulation damage, and electromagnetic interference.
• 🚫 The energy dissipated due to the Corona effect is undesirable as it reduces the efficiency of the transmission system and increases operating costs.
• ⚠️ Intense Corona effects can cause flashover in insulators or between phases, leading to equipment damage if not carefully designed to reduce the corona effect.
• 🌫️ Foggy weather can cause challenges for power transmission by altering the electric field around conductors, leading to Corona discharge, energy loss, audible noise, and increased wear on transmission equipment.

Q & A

What is the Corona effect in high voltage transmission lines?

The Corona effect, also known as Corona discharge, is a phenomenon where the air surrounding high voltage transmission lines ionizes, causing the conductors to glow and produce a hissing noise. It occurs when the electrostatic field across the transmission line conductors is strong enough to ionize the air, typically when the potential gradient reaches 30 kV/cm.

Why does the air ionize around transmission line conductors?

The air ionizes around transmission line conductors when the electric field intensity exceeds 30 kV/cm. At this point, the air can no longer act as an insulator, and the induced current between the conductor starts to flow through the air, causing it to become conductive and ionized.

What are the consequences of the Corona effect on transmission lines?

The Corona effect leads to energy loss in the form of heat and light, reduced transmission efficiency, and the release of ozone gas. It can also cause audible noise and potentially damage insulators and other equipment over time.

What are Corona Rings and how do they mitigate the Corona effect?

Corona Rings, also known as grading rings or anti-corona rings, are devices installed on high voltage transmission lines to control the electric field distribution. They are typically mounted on transmission line towers and are strategically positioned to modify the electric field surrounding the conductors, reducing the field intensity at critical points and minimizing the likelihood of Corona discharge.

How are Corona Rings constructed and what materials are typically used?

Corona Rings are usually constructed from materials with high electrical conductivity and corrosion resistance, such as aluminum or copper. They are often shaped as concentric rings or cylinders with smooth surfaces to facilitate the redistribution of electric field lines.

What is Corona loss and how does it affect power transmission?

Corona loss is the power loss in transmission lines due to the ionization of air molecules near the conductors. This loss manifests as heat and light energy and is undesirable as it reduces the overall efficiency of the power transmission system.

What factors affect the occurrence of Corona discharge?

Factors affecting Corona discharge include conductor size, surface condition, spacing between conductors, supply voltage, atmospheric conditions, and air density. Rough or irregular surfaces, high voltage, and certain weather conditions can increase the likelihood of Corona discharge.

How can the Corona loss be reduced in transmission lines?

Corona loss can be reduced by using conductors with larger diameters, increasing the spacing between conductors, installing Corona Rings, optimizing conductor design, improving insulator performance, and planning transmission line routing to avoid areas with high pollution levels or adverse environmental conditions.

What is the significance of the corona factor equation in understanding Corona losses?

The corona factor equation, empirically derived by FW Peak, helps in understanding the total amount of power loss in a wire due to the Corona effect. It shows that the power loss is related to the radius of the conductor, among other factors, and is used to optimize transmission line design to minimize losses.

What are the advantages and disadvantages of Corona discharge in transmission lines?

Advantages include the dissipation of excess energy to limit voltage surges and the reduction of audible noise from wind-induced conductor vibrations. Disadvantages include energy losses, insulation damage, potential interference with communication systems, and the production of ozone gas which can cause corrosion.

How does foggy weather impact high voltage power transmission and the occurrence of Corona discharge?

Foggy weather can cause Corona discharge by altering the electric field around conductors as water droplets accumulate on their surface. This can lead to energy loss, audible noise, and increased wear on transmission equipment, as well as challenges in transformer cooling and insulation due to high humidity.