| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electromagnetic flowmeter having both a disconnection detecting function and a short-circuit detecting function at low cost without increasing the number of components in a circuit element. <P>SOLUTION: An electromagnetic flowmeter comprises an excitation circuit 7 including a controlling unit (CPU) 5 and a monitoring circuit 4. The controlling unit (CPU) 5 is provided with an abnormality determining unit 5-2. The abnormality determining unit 5-2, when taking one cycle of switching timing of an excitation current as one excitation cycle, determines a disconnection abnormality and a short-circuit abnormality of the excitation circuit 7, based on behavior of a monitoring signal Vc from the monitoring circuit 4 during the one excitation cycle. The monitoring circuit 4, configured based on a circuit configuration of a disconnection detecting function, compares a voltage Vb generated at a connection point between an excitation switching unit 2 and a constant current circuit 3 with a reference voltage Vrf, to output a signal of a level "H" as the monitoring signal Vc when satisfying Vb>Vrf and to output a signal of a level "L" as the monitoring signal Vc when satisfying Vb≤Vrf. <P>COPYRIGHT: (C)2013,JPO&INPIT |
