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String Protections
- There are 3 types of protections:
- Elements of protection against the arch: Its objective is to keep the electric arc away from the insulators to avoid deterioration. In this group the unloaders are included.
- Elements of electric field distribution: Its objective is to evenly distribute the electric field along the string to avoid the appearance of the corona effect. In this group the rings are included.
- Elements that combine both functions: Rackets and rings with sacrificial elements.
- Pieces made of steel.
- They can be manufactured in stainless steel, suitable solution for very corrosive environments
- The appearance of the corona effect depends on several factors:
- Voltage of the line.
- Atmospheric conditions (humidity, air density).
- Number of conductors and diameter of the conductor.
- Roughness / Irregularity of the surface.
- Although voltage is not the only factor that influences the appearance of the corona effect, we can affirm that:
- The lines <161 kV do not usually cause problems of corona effect being the use of the rackets optional rings
- For lines> 161 kV it may be necessary to install electric field distribution elements.