Patent ID: 6804613
Filing Date: 2004-10-12
Classification: G01F

Abstract:
An electromagnetic flowmeter provided with a pipe through which the fluid to be measured is passed, that applies a magnetic field to said fluid driving the excitation coils with an excitation circuit, and thereby measures the flow rate of the fluid passing through said pipe, comprising:a pair of detecting electrodes to detect a flow signal corresponding to the flow rate of the fluid passing through said pipe, an earth electrode whose potential is the reference potential at the time of flow rate measurement, diagnosing signal generators that apply diagnosing signals between said detecting electrodes and said earth electrode, and a diagnosis circuit to detect resistance values between said detecting electrodes and said earth electrode as diagnostic signals, wherein said diagnosing signal generators use alternating signals whose frequency is an integer multiple of the excitation frequency used in said excitation circuit, and wherein said diagnosis circuit synchronizes said excitation frequency with said diagnostic signal frequency.