| 摘要 |
Instrument system including an electronic transmitter for a vibrating-wire differential-pressure sensor at a field location and connected by a two-wire line to a control room. The transmitter includes an oscillator to produce vibrations of the wire at its resonant frequency, and applies to the two-wire line a corresponding alternating voltage signal. The control room equipment converts this raw measurement data to an analog measurement signal. The control room equipment provides for adjustment of the zero and span of this signal, and for linearization with respect to the input differential pressure. The two-wire line carries a direct-current component the average value of which is automatically adjusted at the control room to match the scaled and linearized analog measurement signal. This line current passes through a meter at the transmitter to provide field service personnel with a visual indication of the value of the scaled and linearized measurement signal.
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