| 摘要 |
<p>1450472 Measuring differential pressure electrically GENERAL SIGNAL CORP 15 Jan 1974 [15 Jan 1973] 01814/74 Heading G1N A force-balancd differential pressure gauge includes a casing 50 with first and second pressure chambers 62, 64 and a bellows 72 sensing the pressure difference therebetween, a differential transformer 84 with a core 82 movable by the bellows and feeding a position error signal to a coil 100 on a sleeve 102 disposed in the air-gap 103 of a magnet assembly 104, whereby the bellows is restored to its rest position and the current supplied to the coil provides a measure of the pressure difference. The coil current is fed over a two-conductor transmission line which also carries the supply voltage from a remote measuring station having a D.C. supply connected to terminals 200, 202. The feedback circuit may include a capacitor 113 providing integration of the position error signal at the input of amplifier 110 whereby the bellows is restored with a zero steady-state position error. Diodes 210, 212, 230 and transistor 214 are arranged to provide regulated bi-polar voltages for the amplifiers 112, 114, 116. Amplifier 114 is connected as a Colpitts oscillator to energize the transformer primary winding at 2 kilohertz.</p> |
