Dose the indoor transformer protected by water sprinklers , if yes so how we should apply this and ensuring that no sparking will happen during water fighting with live parts such as bushings
Water us not used in case of transformer fires.
Instead, the vault where indoor transformer is located is made explosion proof. This way, the building and its occupants / equipment are protected against fire.
Water is used in case of outdoor installations to create a blanket over the transformer (to cut-off Oxygen). The system is called Mulsifyer system.