The 420 kV outdoor GCB is designed and developed for growing needs of transmission networks. These GCBs are of Live Tank Design with spring-pneumatic mechanism. Closing is through spring and opening through air pneumatic pressure. The breakers are of double break interrupter design and employ dual flow puffer action for current interruption. This ensures high operational reliability and safety of power transmission. 420 kV breakers are employed in the Indian National grid for its reliability and efficient transmission of Power throughout the country.
These breakers are capable of clearing the severe rate of rise of recovery voltage due to short line faults and high recovery voltage peak due to out of phase switching. Small currents such as capacitor bank switching currents, transformer magnetising currents, cable or line charging current are interrupted smoothly without any re-strikes or re-ignition and over voltages are minimized.