Electromagnetic flowmeter
First Claim
1. An electromagnetic flowmeter excited by a rectangular waveform, comprisingexcitation means for providing excitation to said flowmeter through repeated cycles, each comprising a first quiescent period, a first excitation period, a second quiescent period, a second excitation period for excitation with a polarity opposite to that of said first excitation period, and a third quiescent period;
- sampling means for sampling a signal from electrodes of said flowmeter at equal sampling intervals in each of the periods except said second quiescent period; and
arithmetic means for effecting an arithmetic operation indicated by (Z01 -2M1 +2M2 -Z03) using a sampled value Z01 in said first quiescent period, a sampled value M1 in said first excitation period, a sampled value M2 in said second excitation period, and a sampled value Z03 in said third quiescent period.
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Accused Products
Abstract
An electromagnetic flowmeter is energized by a tri-state excitation system having a first quiescent period, a first excitation period, a second quiescent period, a second excitation period for excitation with a polarity opposite to that of the first excitation period, and a third quiescent period. The electrode signals are sampled at equal intervals in each period except the second quiescent period and combined to provide an output which eliminates noise due to residual magnetic flux, electrochemical effects and commercial frequency.
6 Citations
7 Claims
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1. An electromagnetic flowmeter excited by a rectangular waveform, comprising
excitation means for providing excitation to said flowmeter through repeated cycles, each comprising a first quiescent period, a first excitation period, a second quiescent period, a second excitation period for excitation with a polarity opposite to that of said first excitation period, and a third quiescent period; -
sampling means for sampling a signal from electrodes of said flowmeter at equal sampling intervals in each of the periods except said second quiescent period; and arithmetic means for effecting an arithmetic operation indicated by (Z01 -2M1 +2M2 -Z03) using a sampled value Z01 in said first quiescent period, a sampled value M1 in said first excitation period, a sampled value M2 in said second excitation period, and a sampled value Z03 in said third quiescent period. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification