ECE-320 CH02.pdf - Unix.eng.ua.edu

G. Rizzoni, Principles and Applications of Electrical Engineering Problem solutions, Chapter 2vx( x)out=→ 500110x( x 0.02) + ( 200e∞)( 1−x 0.02)( = 5 V) = 10 cmv out________________________________________________________________________Solution:Problem 2.54Known quantities:Meter resistance of the coil; meter current for full scale deflection; max measurable pressure.Find:a) The circuit required to indicate the pressure measured by a sensorb) The value of each component of the circuit; the linear rangec) The maximum pressure that can accurately be measured.Assumptions:Sensor characteristics follow what is shown in Figure P2.54Analysis:a) A series resistor to drop excess voltage is required.b) At full scale, meter:IrmFS ˆmˆ= 200Ω0. L.:= 10µAVmFS ˆ= ImFS ˆrmˆ= 2 mV.at full scale, sensor (from characteristics):P FS= 100V TFS= 9. 5kPamVKVL : −V+ V + V ˆ = 0VITFS RFS mFSRFS= VTFS−Vmˆ FS= 9.5 mV − 2 mV = 7. 5RFS= ITFS= Imˆ FS= 10µAOhm law:VRFS7.5 mVR = = = 750 ΩI 10 µ ARFSc) from sensor characteristic: 30 kPa –110 kPa.________________________________________________________________________Solution:Problem 2.55Known quantities:Meter resistance of the coil; meter current for full scale deflection; max measurable pressure.Find:a) Redesign the circuit to meet the specification.b) The value of each component of the circuit.c) The linear range of the system..mVx2.42