Power Transmission Lines should be provided with maximum possible service safety to avoid possible damages to insulators and conductors. Flashover is often the cause of outages due to high arc temperature which may damage the conductors and destroy the insulators. Arcing protections is an important feature of equipment design. They consist of horns, Grading rings, the shapes and sizes of which are in accordance with system voltage and standardised by High Voltage Electrical Tests. Aluminium Corona Control Rings are supplied for High Voltage applications above 330KV.

A properly designed protection device will avoid the flashover damaging the insulator string. It will make the arc start away from the conductor and ensure that during all the flashover time the arc is kept away from the insulator string. The ring shape design gives a more linear voltage distribution all along the insulator string, thus avoiding bottom insulator from Electrical over stress. While for system voltage up to 220KV conventional flat type, ball and rod type and tubular racquet type arcing horns are adequate for UHV lines i.e. 400 KV and above special designs are developed. The arcing / grading rings produced both in steel (HDG) and satin finish aluminium alloy tube (UHV application).