The OWK series oil-water alarm detects the oil leakage in the hydrogen-cooled generator units. It has simple structure and is easy to install. It is composed of sheild, float, permanent magnet and magnetic switch. When liquid enters the shell, the float will move. The upper part of the float rod is equipped with a permanent magnet. When the float rises to a certain distance, the magnetic switch will act to turn on the electrical signal, and send out an alarm. When the liquid inside the shell is discharged, the float falls by its own weight, and the magnetic switch acts as a cut-off signal, and the alarm is released. An observation window made of oil-resistant Plexiglas is installed on the shell of the alarm to facilitate the inspection of the liquid level.