What is the definition of "proportional band"?
A type of closed-loop feedback control in which a constant value is multiplied with the error in order to adjust the output. Also known as gain and proportional gain.

Learn more about proportional band in the class PID for PLCs 350 below.


PLCs Training


Class Information
Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:PID for PLCs 350
Description:This class covers the effects of PID control in closed-loop systems as well as methods for tuning your controller in order to achieve the desired performance.
Prerequisites: none
Difficulty:Advanced
Number of Lessons:13
Language:English, Spanish
 
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Class Outline
  • Objectives
  • Industrial Control Systems
  • The Parts of a PID Control System
  • Open-Loop Control Systems
  • Closed-Loop Control Systems
  • Proportional Gain
  • The Effects of Adding Proportional Gain
  • Adding the Integral
  • Adding the Derivative
  • Controller Tuning
  • System Alarms
  • Pros and Cons of PID
  • Summary
  
Class Objectives
  • Describe PID industrial control systems.
  • Describe the basic aspects of a PID control system.
  • Describe open-loop control systems.
  • Describe closed-loop control systems.
  • Describe proportional gain.
  • Calculate the effects of adding proportional gain.
  • Describe the effects of adding integral action to proportional gain.
  • Describe the effects of adding derivative action to integral action and proportional gain.
  • Describe controller tuning.
  • Describe system alarms for PID control systems.
  • Describe the pros and cons of using PID control.

Class Vocabulary

Vocabulary TermDefinition
auto mode A system that is set for closed-loop control.
automatic feedback Feedback that is controlled by an electronic or electromechanical mechanism rather than a person.
autotune A feature in some motor control devices that automatically adjusts the PID control system at start-up.
bias A value between 0 and 100% that is added to the output after the gain calculation brings the controller to the steady state mode. Bias is sometimes used to stabilize a control system.
closed-loop system A type of control system that automatically changes the output based on the difference between the feedback signal to the input signal.
constant value A value that does not change.
control mechanism A system or device that operates or manipulates another system or device.
control system A manual or automatic mechanism used to manage dynamic processes by adjusting or maintaining physical variables such as temperature, speed, or flow rate.
controller A processor driven device that uses logic based software to provide electrical control to machines. Also known as controller or PLC.
controller tuning A system of adjusting the controller's response to error by adjusting values in the PID algorithm.
cruise control A control mechanism for automatically regulating the speed of a vehicle. Cruise control allows the driver to maintain the speed of a car without continually holding down the accelerator pedal.
deadtime The delay between a change in the PV and a change in the output.
delta A mathematical operator used to indicate a change in a value. It is represented by the Greek letter Δ.
derivative control A variable that allows a controller to anticipate whether the PV will overshoot the SP, and reduces the output as needed.
deviation alarm An alarm that alerts the operator that the output is nearing its minimum or maximum allowed value.
error The difference between the SP and the PV. When errors are detected, the controller sends instructions to the control system to adjust the output to compensate.
feedback signal The actual value detected by a sensor as a process is taking place. Also known as the process variable.
gain A type of closed-loop feedback control in which a constant value is multiplied with the error in order to adjust the output. Also known as proportional gain and proportional band.
gain-only control A type of closed-loop system control that uses only the proportional aspect of the PID algorithm.
inner alarm band An alarm system configuration that allows for an early warning as the temperature approaches a minimum or maximum allowed value.
integral A small part of a larger whole. In PID, the integral is a variable time period used to adjust an output.
integral action The time it takes a control system to adjust output once it reaches the setpoint. Adding the integral causes the output to change more rapidly or more slowly based on the integral time specified.
integration The process of dividing an area into small parts and using the sum of those parts to determine the total value.
manual mode A system that is set for open-loop control.
maximum error signal The highest or strongest possible error signal.
open-loop system A type of control system that uses only an input signal to actuate an output. There is no automatic feedback to adjust the process, so adjustments must be made manually by the operator.
oscillate To waver back and forth. Excessive oscillation in a signal can cause a control system to become unstable.
outer alarm band An alarm system configuration that alerts the operator when the output has exceeded its mimimum or maximum allowed value.
overshoot To exceed a set value.
PID One of the most common types of process control. Proportional, integral, derivative control adjusts system outputs when there is a difference between the setpoint and process variable.
PID algorithm A mathematical formula used to control and stablize the outputs of closed-loop control systems. The equation for PID is: Output = Gain (Error + l/Integral Time ∫ Error x deadtime + Derivative Time Constant x ΔError/ ΔTime).
process variable The actual value detected by a sensor as a process is taking place. Also known as the feedback signal.
proportional band A type of closed-loop feedback control in which a constant value is multiplied with the error in order to adjust the output. Also known as gain and proportional gain.
proportional gain A type of closed-loop feedback control in which a constant value is multiplied with the error in order to adjust the output. Also known as gain and proportional band.
proportional, integral, derivative control One of the most common types of process control. PID adjusts system outputs when there is a difference between the setpoint and process variable.
PV Process variable.The actual value detected by a sensor as a process is taking place.
rate A variable that allows a controller to anticipate whether the PV will overshoot the SP, and reduces the output as needed.
reset The time it takes a control system to adjust output once it reaches the setpoint. Reset causes the output to change more rapidly or more slowly based on the integral time specified.
setpoint A preset value such as a specific temperature, speed, or flow rate that the control system is supposed to reach. Also known as the target value.
SP Setpoint. A preset value such as a specific temperature, speed, or flow rate that the control system is supposed to reach.
summing junction The part of a PID control system in which the SP and PV are compared to each other. The difference between the SP and PV is called error.
target value A preset value such as a specific temperature, speed, or flow rate that the control system is supposed to reach. Also known as the setpoint.
undershoot To fall short of a set value.