To reduce oil contamination from moisture in the transformer, which of the following method used?
(1) Use of silica gel breather
(2) Use of rubber diaphragm
(3) Use of gas cushion
(4) Use of thermosyphon filter
1
(1), (3) and (4)
2
(1), (2) and (3)
3
(2), (3) and (4)
4
(1), (2), (3) and (4)