Correct Answer : Option (D) : Protect the transformer form damage when oil expands due to heating.
Explanation : In the transformer, the conservatory provides free space for the expansion of the oil. When the transformer is on full load, the oil heats up and expands. When the load is reduced from the transformer, oil temperature shrinks and oil contracts. Here, the air space in the conservatory enables breathing when oil expands or contracts. It is possible to manufacture a transformer without a conservator, but in that particular case, a tank with a gas cushion is required at the top of the transformer.
