The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to

lubricate the contacts
insulate the contacts from switch body
extinguish the arc
all of the above E. none of the above

The correct answer is D. all of the above.

The oil in high voltage switches serves three main purposes:

  • To lubricate the contacts, which helps to reduce wear and tear and improve the switch’s performance.
  • To insulate the contacts from the switch body, which prevents electrical arcing and ensures that the switch can operate safely.
  • To extinguish the arc, which is created when the contacts open. The oil helps to cool the arc and prevent it from reigniting.

Without the oil, the contacts would wear out more quickly, the switch would be more likely to arc, and it would be less safe to operate.