Zone B Limit Alarm
Alarm rule 6 is triggered when multiple points (in a series) are in or beyond Zone B (upper or lower Zone B).
For alarm rule 6, the limit and length values are used for both the upper and lower charts. The data points on the chart are checked for the specified number of points in or beyond Zone B. For alarm rule 6, an alarm is triggered when there are <Limit> number of data points in the <Length> that are either in or beyond Zone B. You can also use other alarms, 36, 37, 38, or 39.
Features
General guidelines to detect instability in Zone B for different chart types are as follows:
Chart Types | Maximum Points to apply Rule |
|---|---|
X-bar | 4 of 5 successive points in or above upper or lower Zone B |
Individual Chart | |
Median | |
R-chart when the minimum subgroup size is 4 | |
R-chart when the minimum subgroup size is less than 4 | 3 successive points in or above upper Zone B |
Following are the alarm properties defined for Zone B limit Alarm
:
Alarm Name | Property Name | Parameter | Data Type | Description |
|---|---|---|---|---|
Allow Upper Chart Zone B Limit Alarm |
| Boolean | Enables Zone B alarm points for upper charts | |
Allow Lower Chart Zone B Limit Alarm |
| Boolean | Enables Zone B alarm points for lower charts | |
Alarm 6 | Limit of Zone B Limit Alarm |
| Integer | Sets the limit and length values to check data points within Zone B |
Length of Zone B Limit Alarm |
| Integer | ||
Alarm 36 | Limit of Upper Chart Upper Zone B Limit Alarm |
| Integer | Defines the limit and length values to check points in upper Zone B of the upper chart |
Length of Upper Chart Upper Zone B Limit Alarm |
| Integer | ||
Alarm 37 | Limit of Upper Chart Lower Zone B Limit Alarm |
| Integer | Defines the limit and length values to check points in lower Zone B of the upper chart |
Length of Upper Chart Lower Zone B Limit Alarm |
| Integer | ||
Alarm 38 | Limit of Lower Chart Upper Zone B Limit Alarm |
| Integer | Defines the limit and length values to check points in upper Zone B of the lower chart |
Length of Lower Chart Upper Zone B Limit Alarm |
| Integer | ||
Alarm 39 | Limit of Lower Chart Lower Zone B Limit Alarm |
| Integer | Defines the limit and length values to check points in lower Zone B of the upper chart |
Length of Lower Chart Lower Zone B Limit Alarm |
| Integer |
Example
If you define alarm rule 36 with limit and length as 4 and 5 respectively, the alarm rule 36 is violated if only 4 points in a string of 5 adjacent points in the upper chart are lower than or beyond Zone B.
Graphical representation of Zone B Limit Alarm
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