Test results on an electromagnetic current sensor with an open design

An electromagnetic current sensor with a unique 'open' design was tested for steady flow accuracy and cosine response in the horizontal and vertical planes. The sensor's configuration was designed to minimize hydrodynamic disturbances of the current flow and to offer good linearity and directivity response. Test data revealed the sensor's steady-flow measurement uncertainty to be + or -2.5 percent of full scale. Horizontal directivity errors were less than + or -4 cm/s and 5 cm/s for half-and one-knot test flows. The major contributor of error for the cosine response was determined to be an imbalance in amplifier gain between the sensor's two measuring axes.