Emergency automatic plugging device for hydropower station unit flow channel manhole

The invention relates to the technical field of water conservancy and hydropower engineering, and discloses a hydropower station unit flow channel manhole emergency automatic plugging device which comprises an outer gallery, a manhole round hole, a water collection tank, an air supply pipe and an electric wire. The manhole round hole is formed in the rear end of the outer gallery, and the water collection tank is formed in the outer gallery; an air supply pipe and an electric wire are installed on the left wall of the interior of the outer gallery, a leaking stoppage air bag is installed at the bottom end of the interior of the outer gallery, and a pressure reducing valve and a normally-closed electromagnetic valve control air valve are installed on the left wall of the inner wall of the outer gallery. A normally-closed electromagnetic valve can be controlled through a liquid level controller to control an air valve to work so as to inflate the interior of a leaking stoppage air bag, meanwhile, a T-shaped rou