| 摘要 |
PROBLEM TO BE SOLVED: To prevent an output from being changed due to the contamination of an electrode part and to prevent a noise from being generated due to the contact of the electrode part with a fluid floating object by a method wherein a magnetic field is generated in water by a coil and the electrode part which detects an electromotive force generated in the magnetic field is covered with an insulator. SOLUTION: In an electromagnetic log sensor, a coil 40 is wound on a core 30, and one pair of right and left electrode parts 50 are arranged with reference to the advance direction of a ship. Then, an exciting current is made to flow to the coil 40, and a magnetic fieldΦis generated in water. At this time, when a fluid such as water, seawater or the like flows in the direction of an arrow, an electromotive force which is proportional to a flow velocity V is generated from the electrode parts 50. At this time, the electrode parts 50 at the tip part of the electromagnetic log sensor are covered with an insulator 10 such as, e.g. a ceramic or the like. Consequently, the electrode parts 50 do not come into direct contact with the fluid, and they are not contaminated with a stuck substance. As a result, it is possible to prevent an output from being changed due to a contamination and to prevent a noise from being generated due to the contact of the electrode parts 50 with a fluid floting substance.
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