 Welcome to this video, the Ziegler-Nickels Reaction Curve Tuning Calculations. Please note, it is recommended that you view the learning object, Ziegler-Nickels Reaction Curve Process Identification Procedure, before watching this video. A popular procedure for tuning a controller is called the Ziegler-Nickels Reaction Curve Tuning Method. This mathematically based operation was developed in the 1940s. The method begins by putting the controller into the manual mode, which causes the system to be put into an open loop condition. Next, a step change is made by changing the set point to cause a 5-10% change in the controller output. The feedback signal from the sensor that measures the controlled variable is displayed on the computer monitor to show the rate at which the process responds. Called the reaction curve, three different values are obtained from the graph on the monitor. These include the process reaction rate, the unit reaction rate, and the effective delay. Viewing the graph and obtaining the values for the process reaction rate, the unit reaction rate, and the effective delay is called the process identification procedure. The process identification procedure values are used to calculate the proper PID, or proportional integral derivative, settings when tuning a controller. Three control modes of operation are commonly performed by the controller. These include proportional, or P, proportional integral, or PI, and proportional integral derivative, or PID. Using the process identification values, different calculations are performed to determine the proper setting for each mode. The controller has the ability to amplify the amount to which its output changes in proportion to the change applied to its input. Controllers can adjust the amplification either by a proportional gain setting or a proportional band setting. The proportional gain and proportional band formulas are shown here. When making calculations for the proportional integral mode, the proportional settings are different than the ones made for the proportional only mode. Therefore, different proportional formulas are used. These are the formulas for proportional gain and proportional band when in the proportional integral mode. Two different types of integral settings are commonly used on controllers. Reset time, which is measured in minutes per repeat, and reset rate, which is measured in repeats per minute. When the process is very slow, reset time is used because the repeat is measured over a period of minutes. When the process is faster, reset rate is used as the controller's integral setting. These are the formulas for the reset time and reset rate settings in the proportional integral mode. When making calculations for the proportional integral derivative, or PID mode, the proportional and integral settings are different than the ones made for the proportional only or proportional integral modes. Therefore, different proportional and integral formulas are used. The formulas for proportional gain and proportional band settings for the PID mode can be seen here. The reset time and reset rate formulas while in the PID mode can be seen here. The calculation for the proper derivative setting using the PID mode is seen here. The formulas required for performing calculations based on the modes of operation that are performed by the controller are shown in this table. Congratulations! You have completed this video, the Ziegler-Neckels Reaction Curve Tuning Calculations.