WATER LEVEL-DETECTING APPARATUS AND ABNORMAL WATER LEVEL-ALARMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To prevent a water level from being incorrectly detected because of dust or the like and eliminate a power source facility by judging the water level on the basis of whether a response signal to a microwave inquiry signal is received or not. ;SOLUTION: At a normal time, in a state where a responder 2 is located higher than a water level 5, the responder 2 receives an inquiry signal transmitted by an interrogator 1 which can transmit and receive microwaves and sends back a microwave response signal according to stored data. Therefore, the interrogator 1 can receive the response signal, and a judging part judges and outputs that the water level is not abnormal. On the other hand, when the water level 5 rises because of an increase of water to submerge the responder 2, the microwave inquiry signal transmitted from the interrogator 1 is absorbed by water, and the responder 2 cannot receive the signal and cannot send back the response signal to the interrogator 1. The responder 2 is set to not higher than a water level to be detected and it is judged from the presence/ absence of the response signal whether the water level increases over a fixed level. A malfunction by dust or the like is avoided. Since the responder 2 operates with a built-in battery, a power source facility or the like is eliminated.;COPYRIGHT: (C)2000,JPO