Page 5 - Instrumentation and Measurement
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5. CORRECTION ELEMENTS 67
5.1 Introduction……………………………………………………………………………...67
5.1.1 The Range of Actuators………………………………………………………….67
5.2 Pneumatic and Hydraulic Systems………………………………………………………68
5.2.1 Current to Pressure Converter…………………………………………………...68
5.2.2 Pressure Sources…………………………………………………………………68
5.2.3 Control Valves…………………………………………………………………...70
5.2.4 Actuators…………………………………………………………………………70
5.3 Directional Control Valves………………………………………………………………73
5.3.1 Sequencing……………………………………………………………………….76
5.3.2 Shuttle Valve……………………………………………………………………..78
5.4 Flow Control valves……………………………………………………………………...79
5.4.1 Fail-Safe Design………………………………………………………………….81
5.5 Motors……………………………………………………………………………………82
5.5.1 D.C. Motors………………………………………………………………………82
5.6 Case Studies………………………………………………………………………………86
5.6.1 A Liquid Level Process Control System…………………………………………86
5.6.2 A Robot Control System…………………………………………………………86
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