T2Crit limits incorrect in T2Range evolution plots with phase iterations (Q890)

Summary:

When using a SIMCA^® 15 project that has phase iterations (new feature in SIMCA^® 15) in SIMCA^®-online 15 you notice that the values for T2Crit are much higher compared to the values seen in SIMCA^®, or completely missing, in T2Range plots.

T2Crit is are used in SIMCA^®-online as a horizontal control limit in batch evolution T2Range plots. As a result, these plots are scaled incorrectly, which makes it hard to see the T2Range evolution data.

T2Crit is also used in the project configuration wizard when configuring batch evolution alarm limits for T2Range.

Symptoms:

The scaling of the T2Range batch evolution plot is adjusted according to T2Crit making it difficult to see trends.

Cause:

SIMCA^®-online fails to count the number of phase iterations for each batch correctly, resulting in the wrong number of degrees of freedom which affects the calculation of the T2Crit values.

Workaround:

In the T2Range evolution plot, you can turn off T2Crit in plot properties to hide the incorrect values, resulting in that the plot is scaled correctly. You can also turn off the default plot options to show T2Crit by default for a project configuration, by going in to File > Options, and then on the Plot options tab.

If you want to see T2Crit in T2Range evolution plots, you can manually configure alarm limits at the levels you want to use. When you do, you can use the values from SIMCA^® and manually set the alarm limits to the right values.

Status:

Has been fixed in SIMCA^®-online 15.0.1.