Presence of ozone owning to corona

Question

Examoogle · Accepted Answer

Option C: Corrodes the material

Explanation & Concepts:
The phenomenon of corona discharge in high-voltage transmission lines ionizes the surrounding air, leading to the formation of ozone ($O_3$) and other chemical compounds. These chemical byproducts, particularly when combined with atmospheric moisture, form corrosive substances that attack the surface of transmission line conductors and hardware.

Working Principle: When the electric field strength at the conductor surface exceeds the dielectric strength of air, air molecules ionize, creating a glow known as corona. This ionization process provides the energy required for oxygen molecules to dissociate and recombine into ozone. Ozone is a highly reactive oxidizing agent that chemically interacts with metallic surfaces, leading to surface degradation or corrosion over time.

Key Formulas: $E_{max} = \frac{V}{r \cdot \ln(\frac{D}{r})}$ — The maximum electric field intensity at the conductor surface causing corona

Key Points: Corona loss is non-linear and increases significantly as voltage rises above critical disruptive voltage.; Ozone production is a direct byproduct of the air ionization process during corona discharge.; Corrosion is specifically exacerbated when the local environment has high humidity, creating nitric acid ($HNO_3$) in the presence of nitrogen.; Corona also causes audible noise and radio interference.

Advantages: Corona provides a natural discharge path to prevent extreme overvoltage spikes; Acts as an indicator of critical stress levels on high voltage lines

Disadvantages: Power loss; Radio interference; Audible noise; Ozone induced corrosion

Applications: Used in electrostatic precipitators; Used in ozone generators for water purification

Additional Info: Option A and B are incorrect as corona loss itself is a power loss, but it does not directly 'improve' or 'reduce' power factor in the context of electrical system compensation; it acts as a resistive load.. Option D is incorrect as regulation is determined by the $R$ and $L$ parameters of the line, whereas corona is a discharge phenomenon.

Answer: C is correct — The formation of ozone due to the ionization of air during corona discharge is chemically reactive and leads to the corrosion of transmission conductors and supporting hardware.

Exam Tip: Always remember that corona is a lossy phenomenon; in competitive exams, prioritize 'Power Loss', 'Radio Interference', and 'Corrosion' as the primary technical consequences.

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Option A: Improves the power factor

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Option B: Reduces the power factor

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Option D: Improves regulation

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