Link to huaneng
Have you ever noticed a faint humming sound coming from power lines on a windy day? Or perhaps you've seen a purplish glow surrounding a high-voltage transmission tower at night? These phenomena are due to a phenomenon known as corona discharge.
Corona discharge is a type of electrical discharge that occurs when the electric field around a conductor is strong enough to ionize the surrounding air. This ionization creates a faint glow and can produce a crackling or buzzing sound. Corona discharge is typically associated with high-voltage systems, such as power lines, transformers, and transmission towers.
But at what voltage does corona occur? The answer to this question is not as simple as it may seem. Corona discharge can occur at different voltages depending on factors such as air pressure, humidity, conductor size and shape, and the presence of contaminants in the air.
In general, corona discharge is more likely to occur at higher voltages. For example, corona can occur at voltages as low as a few thousand volts in laboratory settings, where the air pressure is controlled and contaminants are minimized. However, in practical applications such as power transmission, corona typically occurs at voltages above 30 kV.
One of the key factors that determine the voltage at which corona occurs is the shape of the conductor. Sharp points or edges on a conductor can produce a higher electric field intensity, making corona discharge more likely to occur. This is why corona discharge is often observed around the edges of transmission towers or on the tips of lightning rods.
Another factor that influences the voltage at which corona occurs is the spacing between conductors. When conductors are close together, the electric field between them is stronger, making corona discharge more likely. This is why corona is often observed on transmission lines with closely spaced conductors, especially on windy days when the conductors may sway closer to each other.
Humidity and air pressure also play a role in determining the voltage at which corona occurs. Higher humidity levels can increase the conductivity of the air, making corona discharge more likely at lower voltages. Similarly, lower air pressure can reduce the breakdown voltage of air, leading to corona discharge at lower voltages.
Contaminants in the air, such as dust, pollution, or salt particles, can also lower the voltage at which corona occurs. These contaminants can create free ions in the air, making it easier for corona discharge to initiate.
In addition to these factors, the frequency of the voltage waveform can also affect the occurrence of corona discharge. At higher frequencies, the skin effect causes the electric field to be concentrated near the surface of the conductor, making corona discharge more likely to occur.
In conclusion, corona discharge can occur at a wide range of voltages depending on various factors such as conductor shape, spacing, humidity, air pressure, contaminants, and frequency. While corona discharge is typically associated with high-voltage systems, it can also occur at lower voltages in certain conditions.
So next time you hear that faint humming sound or see that purplish glow around a power line, remember that you are witnessing the fascinating phenomenon of corona discharge – a complex interplay of electrical, environmental, and physical factors that can occur at a wide range of voltages.
If you want to learn more, please visit our website.
For more types of vibration dampers in transmission linesinformation, please contact us. We will provide professional answers.