上游文通大学 2.4 Null and Deflection Methods SHANGHAI JIAO TONG UNIVERSITY Accuracy Dynamic Property Comparison: 1.Accuracy:deflection instrument's accuracy depends on the calibration of the spring;whereas null instrument's accuracy depends on the accuracy of the standard weights. 2.Dynamic Property:null type instruments have difficulties in tracking dynamic changes,but it may be improved considerably by applying automatic servomechanism. 上游充通大学 SHANGHAI JIAO TONG UNIVERSITY 2.5 Input-output Configuration of Instrument Measurement Systems Output component due to Interfering input interfering input and/ The quantities that cause a Quantities to which the change in the input-output instrument is relations for the desired and unintentionally sensitive. FM,I interfering inputs. Modifying input一 + 0 Output Quantities that the >instrument is specifically Desired input intend to measure. Output component due to desired input and im Fig 2.9 Generalized input-output configuration A scheme suggested by Draper,Mckay Lees,19552.4 Null and Deflection Methods Accuracy & Dynamic Property Comparison: 1. Accuracy: deflection instrument’s accuracy depends on the calibration of the spring; whereas null instrument’s accuracy depends on the accuracy of the standard weights. 2. Dynamic Property: null type instruments have difficulties in tracking dynamic changes, but it may be improved considerably by applying automatic servomechanism. 2.5 Input-output Configuration of Instrument & Measurement Systems Fig 2.9 Generalized input-output configuration A scheme suggested by Draper, Mckay & Lees, 1955 Quantities to which the instrument is unintentionally sensitive. Quantities that the instrument is specifically intend to measure. The quantities that cause a change in the input-output relations for the desired and interfering inputs