What is the signal voltage in millivolts between the sensor electrodes of an electromagnetic flowmeter?
Thread Content
Can the signal between electrodes be measured with a multimeter? The pipeline valves are closed. There are two flow meters with a 150-inch diameter at different locations; why is there still an MV signal between one of the measurement electrodes when there is no flow, with several hundred MVs with respect to ground? ； The signal between the electrodes fluctuates between 0-4 mv, and there are also fluctuations with respect to ground. What could be the cause of this? ? Is there a problem with this sensor electrode, or can’t it be measured with a multimeter?
Electrode measurements generally involve measuring resistance, and accurate readings can only be obtained when the power is off and the electrodes are dry
The signal between the electrodes is on the order of μV, and it is generally difficult for a multimeter to detect it; presumably, electromagnetic flowmeter manufacturers have methods for measuring it.
Moreover, this signal is neither a DC signal nor a standard AC signal. In the case of electromagnetic flowmeters, those driven by rectangular waves produce a signal that is roughly rectangular in shape, while those driven by triangular waves yield a signal that is roughly triangular in shape; therefore, ordinary multimeters with AC measurement functions are unable to detect it.
As mentioned above, on-site multimeter tests generally only measure the resistance values related to the coils and electrodes.