| 摘要 |
PURPOSE:To obtain an electromagnetic flowmeter which measures a flow rate in accordance with a measurement range by measuring a signal from an electrode, provided to a pipe where a fluid to be measured flows, through an integrator whose integral time can be switched. CONSTITUTION:Electrodes 4 and 4' are provided to a pipe 3 where a fluid flows, and signals generated at the electrodes 4 and 4' when a current is flowed through an energizing coil 2 from a current source 5 through a switch 7 are amplified by an amplifier 8, whose output is inputted through a switch SS to an integrator IC consisting of an operational amplifier DP2 and a capacitor C which has a reset switch RS. The output of the integrator is passed through a switch and held by a sample holding circuit 10 with sampling pulses P2. The switches 7, SS and RS are controlled by control pulses P1, P4 and P5 from a control circuit 6 and the control pulse P4 is increased in pulse width in accordance with a measurement range, so that a flow rate is measured in accordance with the measurement range. |
