In which of the following type of circuit breaker the interrupters are supported on porcelain insulators?

Option 4 : Live tank design

Live tank circuit breaker:

• In this type of circuit breaker, the switching unit is located in an insulator bushing which is live at line voltage.
• The interrupters are supported by porcelain insulators.
• Tank circuit breakers are cheaper than the dead tank and require less space.
   

Dead tank circuit breaker:

• The switching unit is located within a metallic container which is kept an earth potential. 
• As the incoming/outgoing conductors are taken through insulated bushings, it is possible to place current transformers on these circuit breakers.
   

Single pressure puffer type circuit breaker:

• In these types of circuit breakers, an arc-extinguishing gas is compressed in conjunction with a braking operation to extinguish the arc generated between contacts.
• A puffer cylinder is a movable hollow cylinder that acts as a bridge between the two fixed contacts. It slides upward and downward axially along the contacts to make and break the contact between the two fixed contacts.
   

Double pressure type circuit breaker:

• The double pressure circuit breaker utilizes a pressurized SF₆ gas chamber that is released into the arcing chamber during operation of the breaker. 
• The puffer type has good breaking properties for all current levels but requires more mechanical force to operate and thus a bigger operating mechanism.