EE 372 Final Exam 100% Correct Answers


1.  In process control the desired value of a system is referred to as the__________?



2.  In process control, the term the “process”, whatever it may be, may also be referred to as the ______________.



3.  The device that exerts a direct influence on the process is called the _____________.


4.  Control system objectives should include:


5.  The response criterion that specifies that the amplitude of each peak of each cyclic response be a quarter of the preceding peak is called_________.


6.  The mathematical relationship between the input of a block and the output of that block is known as the __________ __________.


7.  The equation below describes the response of a __________________ order system.
8.  The current through a RTD can cause the RTD to heat up. This factor is accounted for by use of the ____________________.


9.  Type J, T, K, E, S, and R are all thermocouple types. The letter designates_______________.


10.  Since Thermocouple voltages are small, great care should be taken to protect against electrical noise by_________________.



11.  Strain gauges operate based on the change in ___________________ of a metal under stress.


12.  The primary form of ____________ sensor is the accelerometer.


13.  Flow across an orifice plate varies proportionally with the ___________ of the differential pressure.


14.  A rotameter, a moving vane flow meter and a turbine flow meter all place ________________ in the flow of the material.


15.  Elements of final control are:_______________.


16.  A _________________ is required to condition the signal from a computer so that it might interact with process control equipment.


17.  A simple device that can convert mechanical motion to pneumatic pressure levels is the __________________.


18.  Control valve sizing is done by choosing the valve size with the appropriate ___________________.


19.  A process that can be controlled by reading on or off conditions and responding with other on or off conditions is called a _____________ state system.


20.  Alarm conditions can best be described by_________________________.



21.  Programmable logic controllers can replace electromagnetic relays in control systems.


22.  The below schematic symbol is a _________________.
23.  Could the below circuit be used to control a motor starter?
24.  The process the PLC uses to read the inputs, solve the ladder logic, and drive the outputs is the PLC_____________ for that specific application.



25.  In order for the PLC to interact with the process inputs and outputs the I?O must be compatible with the input signal and output signal __________.


26. Sensor resistance varies from 25 to 1.5 kΩ as a variable changes from cmin to  cmax. Design a signal-conditioning system that provides an output varying from –2 to +2 V as the variable changes from min to max. Power dissipation in the sensor must be kept below 2.5 mW.



The circuit could be implemented as under:



27. A 10-bit unipolar ADC with a reference of 5.00 F and a 44-μs conversion time will be used to collect data on time constant measurement. Thus, the input will be of the form V (t) = 4(1− et/τ ) . What is the minimum value of τ for which reliable data samples can be taken if no Sample-and-Hold circuit is used?



28. A type K thermocouple with a 0°C reference will be used to measure temperature between 200°C and 350°C . Devise a system that will convert this temperature range into an 8-bit digital word with conversion from 00H to 01H at 200°C and from FEH to FFH at 350°C . An ADC is available with a 2.500-V internal reference. At 200°C a type K TC produces 8.13 mV. At 350 °C a type K TC produces 14.29 mV.




 29. A strain gauge has a GF=2.14 and a nominal resistance of 120 Ω . Calculate the resistance change resulting from a strain of 144μin / in .


30. Consider the phototransistor with IV curves below left and used in the circuit below right. Calculate the output voltage when the light intensity is equal to 20 W /m2 .

31. A 4- to 20-mA control signal is loaded by a 100-Ω resistor and must produce a 20- to 40-V motor drive signal. Develop the equation relating the input current to the output voltage. Implement the equation if a power amplifier is available that can output 0 to 100V and has a gain of 10.