What are the disadvantages and advantages of corona ?

The Disadvantages of Corona in Power Lines are as follows

1. Corona results in loss of power due to the discharge along the surface of the conductors.  
2. Corona results in damage to the conductor surface over a period of time.  
3. Corona results in the production of ozone in the atmosphere.  
4. This leads to cracking of elastomeric components like O-rings, gaskets, etc due to the chemical action of ozone. 
5. Insulation of Electric Equipments can be damaged. 
6. The audible noise from the power lines may be annoying. 

While Corona has many disadvantages, it also has an advantage. 

1. Since the corona dissipates energy, the magnitude of steep surges caused by lightning or surges is mitigated as they pass through the lines.