Control System Diagram Labeling and Sequencing Quiz

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What are the three tasks that are always present in control loops?

Measurement, Comparison, Adjustment

Define Process Variable.

The condition of a variable being observed in a process that can change the manufacturing process.

Give examples of common process variables.

Pressure, Flow, Level, Temperature, Density, pH, Liquid interface Mass, Conductivity

What is a Set-point?

A value for a process variable that is desired to be maintained. Signup and view all the answers

Explain Measured Variable.

The condition of a process that must be kept at the designated set-point. Signup and view all the answers

Provide an example where the measured variable is different from the process variable.

Measuring flow into and out of a storage tank to determine tank level. Signup and view all the answers

What is the manipulated variable in a control system?

The variable that is changed to keep the measured variable at setpoint. Signup and view all the answers

Define 'controller' in the context of process control.

The element that decides and commands actions to reduce the error. Signup and view all the answers

Explain what 'controller output (CO)' represents.

The signal from the controller to the final control element. Signup and view all the answers

What is meant by a 'loop' in process control?

The signal flow from measurements to error detector, controller, and final control element. Signup and view all the answers

Define 'instrument' as used in process control.

Any device used for indicating or measuring physical quantities or conditions. Signup and view all the answers

What are 'sensors' in the context of process control?

Devices that detect physical variables and provide measurable outputs. Signup and view all the answers

What is the Process variable in the context of a pressure sensor measuring the level of liquid?

Level of liquid Signup and view all the answers

Identify the Measured variable when a pressure sensor is used to measure the liquid level.

Pressure of liquid Signup and view all the answers

What is the Manipulated variable when controlling the liquid flow based on the pressure measured by a sensor?

Liquid flow Signup and view all the answers

What device is used to change the value of the Manipulated variable in a control system?

Final control element Signup and view all the answers

What is the variable that is changed to maintain the Measured variable at a specific setpoint in a control system?

Manipulated variable Signup and view all the answers

In the context of controlling a loop in a process, what is the proper sequence of Adjustment, Comparison, and Measurement?

Measurement, Comparison and Adjustment Signup and view all the answers

What is the purpose of an Error Detector in a control system?

Detects the difference between actual (measured) values and the corresponding set points (desired values). Signup and view all the answers

In a process control system, what is the role of the Manipulated Variable?

To control the process by adjusting a factor such as steam flow or fluid flow. Signup and view all the answers

What is the feedback path in a control system and how does it contribute to the control process?

The feedback path includes the measured variable, which provides information to the controller for adjustments. Signup and view all the answers

Define the Process Variable in the context of process control.

The process variable is the parameter being controlled, like fluid temperature or flow rate. Signup and view all the answers

What is the final control element in a control system and how does it impact the process?

The final control element, like a valve or pump, directly affects the process variable based on controller inputs. Signup and view all the answers

Explain the role of a Sensor in a process control system.

The sensor, like a temperature sensor, measures the process variable and provides feedback to the controller. Signup and view all the answers

What is the range of a sensor or measurement?

The lowest and highest values it can measure within its specification. Signup and view all the answers

Define the span of a sensor.

The high end of the Range minus the low end of the Range. Signup and view all the answers

How is accuracy of an instrument determined?

By comparing an indicated reading to that of a known standard. Signup and view all the answers

How is accuracy typically specified?

As a plus-or-minus deviation from true, normally specified as a percentage of reading, span, or full-scale reading or deflection (% FSD). Signup and view all the answers

What is the range of a pressure sensor that has a range of 25 to 150 psi?

25 to 150 psi Signup and view all the answers

Why should instruments be selected with a range that includes expected disturbances and possible failures?

To ensure that the sensor can measure all values a process will normally encounter. Signup and view all the answers