An increase in temperature causes the oil in the transformer to expand. The conservator provides space for this expansion of the oil. The oil level indicator in the conservator needs to be monitored to ensure that the level of oil does not fall below the alarm limit.
As the level of oil rises and falls inside the conservator, air enters and leaves the chamber. The air may carry moisture which may cause the oil to deteriorate. Breathers filled with silica gels are provided to separate moisture from the aspirated air.
The silica gel turns blue when it becomes saturated with moisture after which it needs to be replaced.