Process Control & PID Controllers : Principles Design Tuning

Explore core concepts of process control and pid controllers through practical examples, tuning guidelines, and process dynamics, guided by the Ziegler Nicole method for optimum performance.

Explore the fundamentals of automatic controls for process and HVAC systems, focusing on valve-controlled flow control, measurements of temperature, pressure, level and flow, and time-dependent responses.

Explore why process plants need automatic controls to ensure safety, stability, and accuracy, delivering steady, predictable operations and reducing unplanned shutdowns, while improving quality and production efficiency.

Explore standard control terminology used in process engineering, including manipulated variable, control device, controlled variable, set point, and deviation, as operators regulate water level with an inlet valve.

Apply the elements of automatic control to regulate water level toward a set point. Map the eye as a sensor, brain as a controller, and inlet valve as control device.

Assess how a typical process manages safety and stability by avoiding water overflow or starvation, with accuracy limited as the operator relies on visible errors and constant attention.

Define key terms in process control, including set point, desired value, control value, deviation, and offset, and show how sensors, controllers, actuators, and valves regulate the controlled medium.

Automatic temperature control replaces manual valve operation, handling varying flow and rapid heat changes from steam to heat water from t1 to t2, with alarms for safety.

Explore automatic process control by linking a controlled condition such as temperature with a measuring element like a temperature sensor, using valves as the control device.

Identify the basic control system components: sensor, controller, actuator, and valves; explain how electrical, pneumatic, hydraulic, and mechanical energy power them, and classify valves by action and configuration.

Master the principles of process control and the design and tuning of PID controllers, and learn key steps to take before proceeding to the next section.

Explore two control modes in process control: on-off and continuous control, demonstrated by an automatic temperature control system with a valve, actuator, controller, and sensor set to the set point.

Explore on/off control, a two-step thermostat action with 59 and 61 degrees switching, covering switching and operating differentials, heat transfer delays, and its heating system applications.

Explore continuous control, where a valve modulates opening rather than on-off, and proportional, integral, and derivative actions form PI, PD, or PID configurations.

Learn proportional control (P) as the foundational continuous control action, detailing how the proportional band affects stability and offset through a water tank analogy.

Demonstrates proportional temperature control of a building using a water heating system, with a 6 percent proportional band around 18 degrees celsius set point, showing load effects and sustained offset.

Explore gain in proportional control, the reciprocal of the proportional band, and how output scales with error and how the band affects sensitivity, stability, and oscillation risk.

Explain reverse and direct acting control signals in proportional control, showing how a rise in temperature lowers or raises the control signal and how the pneumatic dial inverts valve action.

Explain how the Foxboro 43AP pneumatic indicating controller uses proportional, integral, and derivative settings in a closed-loop control with pneumatic output up to 1.4 bar, regulators, and manual/auto operation.

Explore how proportional control creates an offset between set point and temperature, with a 6 °C band and a 2 °C offset, illustrating proportional effect when the set point shifts.

Apply manual or automatic removal of set-point offset. Manual reset shifts the set point by two degrees, matching room temperature at 18 degrees with 83% valve opening.

Explore how integral action automatically resets a proportional controller to eliminate steady-state error by integrating the control deviation over time.

Explore integral control (i) in pid systems, addressing overshoot and integral wind-up caused by time lags and large errors, and learn strategies to prevent wind-up in proportional and pid controllers.

Explore how derivative control (D) measures the rate of change of the process signal to minimize overshoot and deviation from the set point during changes, especially with time lags.

Explain the three-term controller, detailing proportional, integral, and derivative actions with adjustable gain for stability, offset compensation for load changes, and rate action to speed valve movement during rapid changes.

Explain the time constant in process control by comparing two definitions: time to reach final value from initial, and time to change 63.2% due to a step load.

Identify how hunting causes instability in temperature control. Explain hunting stems from a narrow proportional band, short integral time, long derivative time, or dead times, and PID tuning stops it.

Explore hunting in a steam-to-water heat exchanger control system, where a sudden load drop drives valve action, causing outlet temperature spikes and unstable cycling, accelerating wear.

Lag is a delay in response in both the control system and the process, such as control lag and thermal lag in heating a room with a thermostat.

Explore rangeability, the ratio of maximum to minimum controllable flow. Learn fast opening, linear, and equal percentage valve characteristics and their relation to opening under constant pressure.

Explore process control and PID controllers, focusing on principles, design, tuning, as you prepare to proceed to the next section.

Explore complete control systems comprising the valve, actuator, sensor, and controller, and examine the dynamics of the process.

Identify the two types of control loops: open loop and closed loop control systems, and examine each type in detail across upcoming videos.

Explain open loop control as a system with no feedback from the room. Demonstrate outside temperature sensing and a remote set point that provide coarse control.

Describe closed loop control with room-temperature feedback. Enable valve and actuator control via the internal temperature sensor to regulate the space.

Explore feedback control as a closed-loop approach that compensates disturbances such as load changes and external influences by feeding back information to the controller and applying corrective action.

Apply feedforward control to anticipate disturbances and act before the event. In a steam boiler, raise the boiler to high fire before opening the steam valve, enabling a controlled startup.

Understand single loop control for a steam to water heat exchanger. A thermocouple or platinum resistance thermometer senses water temperature and compares it to the set point, driving the valve.

demonstrates multi-loop humidity control for a slow moving timber product, with a primary loop adding water and a secondary loop offsetting the local set point to improve control.

Explain cascade control with a master and slave controller and two sensors, guiding the valve to regulate a steam jacketed vessel so product temperature stays within limits and rises safely.

Demonstrate ratio control by maintaining a two-to-one acid-to-water mix through flow measurements, ratio calculations, and setpoint-driven valve signals, and illustrate furnace air–fuel balance with louvres.

Understand split range control, where a single controller splits the 0–100% output to multiple valves. Explore non symmetrical splitting, overlap, disjointed areas, and three areas in a tank pressure control.

Explore how electric, pneumatic, and digital control systems perform operations on signals—addition, subtraction, multiplication, ratio, square root, and max/min—applied to process variables and set points in a heat exchanger example.

Explore process control principles and PID controller design and tuning as you prepare to advance to the next section.

Explore process dynamics and time constants, including sensor and transmission delays, pneumatic versus electric actuation, and how time lag shapes controller choice, tuning, and system response.

Analyze how step input reveals a process's dynamic characteristics, including dead time, time constant, and first-order and second-order responses, and explain control challenges when dead time dominates.

Explore the principles of process control and PID controllers, focusing on design and tuning concepts, with guidance before proceeding to the next section.

Explore available process control choices and the decisions before selection, noting that guidance rather than rules applies as factors like costs, personal preferences, and current fashions influence choices.

Align safety, stability, and accuracy with valve selection and control strategy. Assess application details—set points, variable loads, process type, fluids, differential pressure, materials, and motive power—to choose loop type.

Self-acting controls derive power from an enclosed hydraulic or gas system, delivering maintenance-free, robust proportional control with high range and easy installation, but lack integral/derivative functions and valve position indication.

Utilize pneumatic controls to drive rack and pinion or scotch yoke actuators, enabling fast, robust, and precise valve operation with fail open/close options.

Electric controls power actuators to achieve high accuracy positioning, using on off or combined modes, while installation, wiring, and hazardous area safety demands intrinsically safe or explosion proof controls.

Explore how electro pneumatic controls merge electronic precision with pneumatic actuation in a temperature control system, using a numerically actuated valve, sensor, and positioner with fail-safe and intrinsic safety options.

Identify how load changes and set value criticality influence controller choice, with self acting, electric, or electro pneumatic controls for constant loads, slow load variations, or changing demands.

Different applications require different control systems; self acting and pneumatic are for slow load variations with offset tolerance, while electro pneumatic or electric with electronic programmable controllers suit tighter requirements.

Select valve types based on power mode and medium, balancing actuator speed, accuracy, and differential pressure, with steam favoring two-port valves and liquids allowing two- or three-port options.

Assess safety during power failures, decide valve fail-safe position, and choose direct or reverse acting control, with on-off, proportional, integral, or pid actions, avoiding set-point isolation.

Explore core principles of process control, pid controller design and tuning, and apply them as you prepare to proceed to the next section.

Install valves with proper size, rating, and support; fit upstream strainers to prevent dirt damage. Maintain access, observe bypass options, and follow manufacturer instructions for installation, testing, and steam conditioning.

Follow manufacturer guidelines for actuators mounted above the valve, away from heat, humidity, and corrosive fumes, and use sensor pockets to ensure immersion and minimize response delays, considering enclosure ratings.

Ensure dry, oil-free, dirt-free and leak-tight compressed air and signal lines in a nomadic system, and locate the controller near the valve and actuator to minimize delay and ensure valve stroke.

Ensure proper electrical wiring for electric, electronic, and electro-pneumatic controls to prevent damage from incorrect connections and noise; use screened cables, earth conduit, and protect cables per local regulations.

Tune the proportional band, integral time, and derivative time to fit each application, balancing offset, set point return, and stability against load changes.

the lecture introduces the ziegler-nichols method for tuning pid controllers, using the instability point to obtain the critical period and proportional band, then determine starting p, pi, and pid settings.

Explain bumpless transfer in process control by detailing auto to manual handover, how to match outputs, and maintain flow control without interrupting the loop.

Self-tuning controllers replace commissioning engineers by using on-off control to analyze responses and set pid terms, with adaptive functions that monitor and reset terms during normal operation.

Review the core principles of process control and PID controllers, and explore design and tuning concepts before proceeding to the next section.

Explore how computers power control systems, reading sensors against the set point, using single and multi-loop controllers to determine the corrective action and output signal.

Trace the evolution of process control from nomadic analog controllers to digital systems, I/O devices, distributed control, and field bus bridges shaping modern PID tuning.

Understand that field based protocols are not directly compatible, making integration costly. Users then adopt one system exclusively, with signals interfaced to the field through input-output units.

Explore how fieldbus technology reduces hardware and wiring, enhances safety with local bridges, improves process information and proactive maintenance, and enables flexible, scalable installation and plant integration.

Explore the principles of process control and PID controllers, with design and tuning insights, and prepare to complete this online course.

Explore the principles of process control and PID controller design and tuning with a bonus lecture addressing advanced topics in automation.