The Development Of A Spherical, Electromagnetic Current Meter

This paper describes a totally new concept in water current measurement using proven electromagnetic technology in an instrument which is totally enclosed within the sensors. This configuration results in an instrument which does not introduce errors in the measurement due to disturbance of the flow by the instrument. The instrument is spherical in shape with a diameter of 25 cm. Electrodes are located on the surface of the sphere; the compass and all electronics including data storage as well as the power supply are located within the sphere. Mooring attachment is by means of pad eyes located on the North and South poles. The geometrically symmetrical sensor configuration affords inherently cosinusoidal directional response. The spherical configuration with no protuberances results in an exceptionally simple and robust instrument. EPROM - formatted micro-processor design permits flexibility and simplicity of user interface. Data are stored in a one megabit solid state memory. The data may be retrieved without opening the instrument thus improving reliability and durability. Development, testing, and field deployment of the current meter is described.