What is the use of conservator, buchholz relay, breather in a transformer ?

Buchholz relay - Buchholz relay is to protect the winding from over heat, and the circuit will be tripped off as soon as the coil attains a pre-determined temp .

Conservator - Conservator is to store additional cooling oil, and same oil can be make use later.

Breather - Breather is to absorbe moisture contents from air which sucks in while the oil get expanded.

Conservator Breather buchholz Relay