An electronic actuation system for a pressure equalizing device in a downhole apparatus such as a wellbore plug is described. The system includes a pressure sensor for measuring pressure in the wellbore, and means for setting a reference pressure value using a measurement from the pressure sensor. In a method of use, an applied pressure value is determined using a measurement from the pressure sensor and the reference pressure value, and the device is actuated, or opened, when the applied pressure meets a pre-determined condition, such as falling within a pressure window for certain time period. The invention allows natural changes in wellbore pressure to be accounted for when detecting a pressure actuation event.