Improvements in or relating to electromagnetic flowmeters

1,104,207. Electromagnetic flowmeters. MAWDSLEY'S Ltd. Feb. 13, 1967 [March 4, 1966], No. 9573/66. Heading G1N. In an electromagnetic flowmeter, a voltage measuring circuit 15 is connectable by a switch 14 either to the output terminals 6 of the measuring electrodes 3, or to an adjustable phase and amplitude circuit 7, which is adjusted to provide an output equal in phase and magnitude to the residual voltage produced by the electrode 3 under zero flow conditions. This residual voltage is due to mutual inductance between the field coils 4 and the connections 5 to the measuring electrodes, and the voltage measuring circuit 15 is adjusted to read zero with the switch 14 in the position shown, to compensate for this. The adjustable circuit 7 is energized by a current transformer 8 in the A. C. supply to the field coils 4. The potentiometer P1 adjusts amplitude, and P2 phase.