Transformer pressure-maintaining exhaust device

The utility model relates to a pressure maintaining and exhausting device of a transformer. The device comprises a floating ball mechanism, an inflating mechanism and a control unit, the floating ballmechanism comprises a sliding block moving cavity and a moving rod; the lower part of the sliding block movement cavity is provided with a vent hole interface which is butted with a vent hole of thetransformer expansion tank; a sliding block capable of sliding up and down along an internal track of the sliding block moving cavity is arranged at the upper end of the moving rod; the lower end of the moving rod extends out of the vent hole interface; a floating ball capable of floating up and down along with the oil level in the oil conservator is arranged at the lower end; an inflation closinglimiter capable of being triggered by the sliding block is arranged at the upper part of the inner side of the sliding block moving cavity; the inflation mechanism comprises an inflation pipeline, one end of the inflation pipe