4A - I - Energy Plant Instrumentation and Controls Questions and Answers 100% Correct

4A - I - Energy Plant Instrumentation and Controls Questions and Answers 100% Correct When a process variable has no method of sending information to the final control element the system is known as a) an automatic system b) an open loop system c) a cascading system d) feedback system e) feedforward system b) an open loop system An open loop control system requires a) a transducer and a recorder b) minimum deviation from set point c) a very small amount of dead time or lag d) constant attention e) two final control elements d) constant attention A process variable which is adjusted in order to maintain or achieve some desired value of another variable is termed the a) process variable b) final variable c) manipulated variable d) controlled variable e) transmitting variable c) manipulated variable A control loop controller a) does not require a set point value b) sends a signal to a primary element c) measures the manipulated variable value, eliminating the need of a primary element d) will always eliminate deviation e) constantly compares input signals to the set point e) constantly compares input signals to the set point A common air pressure range for pneumatic control systems is a) 3 to 15 kPa b) 20 to 100 psi c) 20 to 30 kPa d) 40 to 60 psi e) 20 to 100 kPa e) 20 to 100 kPa A very important requirement for a pneumatic control system is a) maximum transmitter output signal pressure must be maintained b) air supply must be clean and dry c) tubing diameters must be kept large d) noise attenuation must be used at each bleed device e) a proper sized compressor which will run continuously b) air supply must be clean and dry The apparatus which converts