Process Control Quiz Questions With Answers

Process control is popular because it offers benefits in terms of safety, profitability, and operability. By implementing process control, companies can ensure the safety of their operations by monitoring and controlling various parameters to prevent accidents and hazards. Additionally, process control helps optimize processes, leading to increased profitability by reducing waste, improving efficiency, and maximizing production output. Moreover, process control enhances operability by providing real-time data and control capabilities, allowing operators to make informed decisions and quickly respond to changes in the process. Therefore, all of these factors contribute to the popularity of process control.

The measure of acidity or alkalinity is pH, which stands for "potential of hydrogen". It is a scale ranging from 0 to 14, with 7 being neutral. A pH value below 7 indicates acidity, while a value above 7 indicates alkalinity. The lowercase "ph" is incorrect as it is not the standard abbreviation for pH.

Process control can be achieved either in the open or closed-loop mode. In the open-loop mode, the control system does not receive feedback from the process being controlled. It simply sends commands or inputs to the process based on a predetermined set of instructions. This mode is commonly used when the process is simple and does not require constant monitoring or adjustment. In contrast, the closed-loop mode involves the use of feedback from sensors to continuously monitor the process and make adjustments as needed. This mode is more commonly used in complex processes where accuracy and stability are critical.

Process instrumentation refers to the set of devices used in industrial processes to measure, record, and control various parameters. These devices include primary sensing elements, which directly sense the process variables, indicators that display the measured values, and transmitters that transmit the measured data to a control system. Process instrumentation plays a crucial role in ensuring the efficiency, safety, and reliability of industrial processes by providing accurate and real-time data for monitoring and control purposes.

It is the open-loop mode that does not take the actual value of the controlled variable into account as there is no feedback loop.

The primary purpose of process control is to maintain some physical variable. Process control is used to regulate and maintain specific physical parameters such as temperature, pressure, flow rate, or level within a system or process. By monitoring and adjusting these physical variables, process control ensures that the desired conditions are met and maintained, leading to efficient and effective operation of the process.

The setpoint is the desired value of the variable being controlled. It can be set manually or automatically, or programmed by the operator.

Voltage, current, and air pressure are the three analog controller signals.

A current range of 4 to 20 mA is used for analog controller signals because it allows transmitter devices to be powered by the same loop, as there is always a minimum current of 4 mA. This ensures that the devices receive sufficient power for operation. Additionally, a 0 mA current allows us to detect failures in the loop, as any deviation from the expected current range indicates a fault or malfunction. Therefore, both of these reasons justify the use of a current range of 4 to 20 mA for analog controller signals.

Disturbances refer to varying conditions that can cause the controlled variable to deviate from the setpoint. These conditions can be external factors or internal changes within the system that disrupt the desired state. By understanding and managing disturbances, control systems can adjust and maintain the controlled variable closer to the setpoint, ensuring stability and optimal performance.

The term "process" refers to an operation or sequence of operations that brings about a change in the controlled variable. It implies a series of steps or actions that are undertaken to achieve a desired outcome or result. In the context of this question, the process is the means by which the controlled variable is altered or modified. It could involve various actions, procedures, or methods that are followed to bring about the desired change.

ISA stands for Instrument Society of America. This organization is a global, nonprofit professional association that sets standards and provides education and training in the field of automation and control systems. The society focuses on promoting the understanding and application of instrumentation and automation technologies in various industries. The other options, Industrial Safety Authority, Industrial Safety Act, and Industrial Standards Association, do not accurately represent the acronym ISA in this context.

A control element is a device that is used to manipulate a variable which directly affects the controlled variable. It is responsible for making adjustments or changes to the controlled variable in order to maintain a desired outcome or setpoint. The control element can be a physical device, such as a valve or a motor, or it can be a software component in a control system. Its purpose is to ensure that the controlled variable remains within a specified range or target value by adjusting the variable that has an impact on it.

The controller in a control loop continuously compares the setpoint (desired value) to the measured variable (actual value) and makes adjustments to the control element to minimize the difference between the two. This process continues until the loop reaches a state of equilibrium where the setpoint and measured variable are equal, known as the steady state. In this state, the controller no longer needs to make corrections as the system is operating as desired.

The term "tag number" refers to a combination of letters and numbers that is used to identify and represent the function and nature of a component. This alphanumeric code helps in categorizing and organizing different components, making it easier to locate and understand their purpose. By using a tag number, individuals can quickly identify and refer to specific components without confusion or ambiguity.

The controlled variable is a function of the manipulated variable and the disturbances. In a control system, the controlled variable refers to the quantity or condition that is being regulated or controlled. It is influenced by both the manipulated variable, which is the input or action taken to control the system, and the disturbances, which are external factors that can affect the system's behavior. The controlled variable is the output of the system and its value is determined by the interaction between the manipulated variable and the disturbances.

A feedback loop is a system component that includes a sensing element to measure the actual value of the controlled variable. It then generates a proportional signal that is sent back to the controller. This allows the controller to continuously monitor and adjust the controlled variable based on the feedback received, ensuring that it stays at the desired value. The feedback loop plays a crucial role in maintaining stability and accuracy in control systems.

When many variables must be controlled simultaneously, this is known as multiloop control. Multiloop control refers to a control system that involves multiple feedback loops, where each loop is responsible for controlling a specific variable. This approach allows for more precise and efficient control of complex systems by considering the interdependencies between different variables. By implementing multiloop control, it becomes possible to optimize the overall performance of the system and ensure that all variables are maintained within desired ranges.