Conservator is a cylindrical tank mounted on supporting structure on the roof of the transformer’s main tank.
When volume of transformer insulating oil increases due to load and ambient temperature, the vacant space above the oil level inside the conservator is partially occupied by the expanded oil. Consequently, corresponding quantity of air of that space is pushed away through breather. On other hand, when load of transformer decreases, the transformer is switched off and when the ambient temperature decreases, the oil inside the transformer contracts. This causes outside air to enter in the conservator tank of transformer through silica gel breather. Thus it provides a buffer space for the breathing of transformer. Apart from this, it acts as an expansion tank and rides over the transformer tank. This means oil will be replenished from this expansion tank in case of any leak from the transformer tank.