A magnetic flowmeter whose electromagnet is excited by a low-frequency excitation current, the flowmeter including flow tube electrodes yielding a flow rate signal. A reference voltage-detecting transformer is provided in the excitation circuit to produce a reference voltage that reflects fluctuations in the excitation current. Fluctuations in the flow rate signal as a result of fluctuations in the excitation current are eliminated by dividing the flow rate signal by the reference-voltage signal.

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