Detailed Reporting Tools Included
Automatically create a detailed analysis report in Microsoft Word format for every loop in your plant. If problems occur later, you have a detailed report for comparison.
After tuning a PID loop, one mouse click creates a detailed loop report with all the analysis graphs and tuning values. You can also select additional analysis options added. For example, the power spectral plots pinpoint the cause of cyclic disturbances. The hysteresis graph helps tell you if your valve is wearing out or sized incorrectly. The robustness plot tells you how sensitive your loop is to process changes with whatever tuning you have.
All these plots and companion analysis information appear within the Word report document. You can completely customize and configure reports. In the Word template, choose the location and size of added analysis pictures or text. It automatically generates a summary and conclusion based on information entered.
The template provided with ExperTune allows you to add all the items below. However the template is completely customizable. You can add to existing loop report or start new one. When you first add an item to a report ExperTune starts Word if it is not already running. Reporting includes detailed analysis of Hysteresis and Linearization.
View a Sample Report: Download Word Document.
View statistics before and after. See how the standard deviation, variability, and valve wear have improved.
Analyze the grouping of your PV, CO, and Errors. The histogram shows the statistical spread of your data. From noisy data determine if there is an offset one side or the other. For example, an inverse bell curve indicates a probable valve stiction problem. Well tuned loops have a tall thin bell curve. Poorly tuned loops have a short fat bell curve.
You can select the IAE (integrated absolute error) and valve wear indicators to select per hour, day, week, month, or year.
The IAE is a measure of performance. It is the area on the time graph between the setpoint and the process variable. Smaller IAEs are better since it means you were running closer to setpoint for that time. IAE is useful since in some plants it can be related closer to dollars and economics of the plant than any other performance indicator.
In many loops, you want to operate as close as possible to specification without straying off. For example, you need to add an expensive ingredient called MTBE to a gasoline so that the final concentration of MTBE is 2%. Adding more than 2% MTBE is giving it away.
But you need to add enough MTBE to reach 2%. So, typically you would have a set point of slightly higher than 2% MTBE. The better the tuning and lower the IAE, the closer to 2% you are able to set your loop and the less MTBE you will use.
The histogram to the right was taken from normal operating data and indicates a stiction cycle in the loop. The two humps, circled in red, show that the PV was usually on either side of the setpoint. If your loop exhibits this type of histogram, you should perform a stiction check on the loop to verify the loop contains stiction.
Time Line Analysis
Use the Time Line Analysis to help understand the relationships between the time of each component in the control loop. For example, the sample interval should always be shorter than the dead time in the loop. If the sample interval is close to the dead time then shortening the sample interval will improve the performance of the loop.
After ExperTune software makes all the necessary conversions, the following time elements of your control loop are plotted on the time line:
ExperTune evaluates the elements on the time line and reports to you. Green bars indicate OK. Yellow is caution and Red indicates you can make improvements that will significantly improve performance.
The following items are evaluated and checked.
- Sample Interval compared to Dead Time
- PV Filter compared to Controller Derivative Time
- Controller Derivative compared to Controller Integral Time
- PV Filter compared to Dead Time
As with all of ExperTune's analysis, with one click ExperTune creates a full report in Microsoft Word including the Time Line plot, all the items on it, and the comparison ratios. The report documents your loop for future records.Video Presentation: Check Control Loop Basics with a Time Line
Tuning is a compromise between performance, robustness and valve wear. You want to increase loop performance, but increasing performance can also reduce robustness and valve wear. ExperTune shows you all the performance indicators in one concise window. So you can view overall trade-offs at a glance.
The Performance Summary Window provides a concise listing of the:
- Performance Increase
- Robustness Increase
- Valve Travel Index
- Valve Reversal Index
- Relative Response Time (RRT) with Current and New Tuning
In one glance you can now easily compare and evaluate the trade-offs in your control loop. (Advanced Loop Optimizer only) Quickly compare:
- Robustness See the tutorial on Robustness Plots.
- Valve wear (travel and reversals)
- Relative response time (RRT)
PID Loop Optimizer Does Much, Much More
Far beyond basic loop tuning, the PID Loop Optimizer Software does much more, including:
- Fast & Easy PID Tuning
- Process Modeling & Advanced Tuning
- Valve & Instrument Diagnostics
- Tools for Specific Applications
- Eliminate Interactions Between Loops
- Advanced Control Tools
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