The cooler of each oil immersed power transformer is equipped with a 水 洩漏 detector. As the pipeline of oil immersed power transformer cooler is a double-layer pipeline, when the pipeline inside the cooler heat exchanger leaks, the 水 洩漏 monitoring device will send an alarm signal, and observe whether there is water leakage by observing the inspection window on the water leakage detector during rotation.