{"id":58872,"date":"2023-02-17T14:59:57","date_gmt":"2023-02-17T06:59:57","guid":{"rendered":"https:\/\/oihelp.corporate.ifs.com\/help\/sentinel\/sentinel-processes\/process-variable-surveillance-process\/"},"modified":"2024-07-09T10:02:46","modified_gmt":"2024-07-09T02:02:46","slug":"process-variable-surveillance-process","status":"publish","type":"page","link":"https:\/\/oihelp.corporate.ifs.com\/help\/sentinel\/sentinel-processes\/process-variable-surveillance-process\/","title":{"rendered":"Process Variable Surveillance Process"},"content":{"rendered":"\n

The Process Variable Surveillance process compares process variable data against defined limits and conditions.<\/p>\n

Process Variable Surveillance is a complex process capable of concurrently monitoring multiple conditions such as transgression of limits, state duration, and movement between states.<\/p>\n

State Transition Rules<\/h2>\n

The Process Variable Surveillance process has clearly defined state transition logic paths. Transition from one state to another is equally dependent on the current evaluation of data, and on the current state.<\/p>\n

State transitions cause events to be raised, allowing for the escalation of actions via the Sentinel framework. Different actions can be assigned to different state outcomes.<\/p>\n

The following table outlines the allowable state transitions of the Process Variable Surveillance process.<\/p>\n\n\n\n\n\n\n\n\n\n\n
This state can transition to<\/strong><\/td>\n\u00a0<\/td>\nThis state<\/strong><\/td>\n<\/tr>\n
Default<\/td>\n<\/td>\nPrimary<\/td>\n<\/tr>\n
Primary<\/td>\n<\/td>\nSecondary<\/td>\n<\/tr>\n
<\/td>\nTertiary*<\/td>\n<\/tr>\n
<\/td>\nDefault<\/td>\n<\/tr>\n
Secondary<\/td>\n<\/td>\nTertiary<\/td>\n<\/tr>\n
<\/td>\nDefault<\/td>\n<\/tr>\n
Tertiary<\/td>\n<\/td>\nDefault<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

*Note: Primary State can only transition to Tertiary State if the Tertiary Limit is breached, and not for any other conditions.<\/p>\n

The following diagram outlines the state transition logic of the Process Variable Surveillance process.<\/p>\n\n\n\n
<\/td>\nD<\/strong> Default
\nP<\/strong> Primary
\nS<\/strong> Secondary
\nT<\/strong> Tertiary<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

Test Outcomes<\/h2>\n

A number of outcomes are possible when the Process Variable Surveillance process is executed:<\/p>\n\n\n\n\n\n\n\n
Default State<\/strong><\/td>\nData is not in an erroneous state and is within the operating envelope.<\/td>\n<\/tr>\n
Primary State<\/strong><\/td>\nData is measured against a primary limit (fixed or variable). If it exceeds the primary limit (for a Maximum Operating Envelope), or if it is lower than the primary limit (for a Minimum Operating Envelope), a Primary State is reached.<\/td>\n<\/tr>\n
Secondary State<\/strong><\/td>\nA number of possible conditions can cause a secondary state. These are explained in more detail in the Secondary State section.<\/td>\n<\/tr>\n
Tertiary State<\/strong><\/td>\nAs with the secondary state, a number of conditions can cause a tertiary state. These are explained in more detail in the Tertiary State section.<\/td>\n<\/tr>\n
Suppressed State<\/strong><\/td>\nThe monitor has been suppressed. For example, if the precondition has not been met.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Output Status Tag<\/h3>\n

For tertiary and secondary states, you can set an output status tag.<\/p>\n

This tag is an entity attribute, or a tag, either as it is, or as part of a calculation. If a secondary output status tag is set, the tag will show a status of one within Explorer when a secondary state is reached, and zero for any other state. Similar behaviour applies to the tertiary output status tag (one for tertiary state, zero for any other state). Within Explorer, the status tag can be observed, for example altering a shape's appearance to indicate whether the monitor's data item is in a secondary \/ tertiary state or not.<\/p>\n

Conditional Logic<\/h2>\n

The Process Variable Surveillance process provides the following conditional logic.<\/p>\n

Note: All of the example graphs in the following sections show tests that have used the Last Known Value sample method.<\/p>\n

Rolling Sum Period<\/h3>\n

A secondary state rolling sum period can be defined for evaluating some of the secondary state conditions; likewise, a tertiary state rolling sum period can be defined for evaluating some of the tertiary state conditions.<\/p>\n

The rolling sum period is a defined period (specified in days and hours). At every sample interval, the rolling sum period is that period preceding the sample interval. So, for example, if the secondary state rolling sum period is set at 1 day 2 hours then at 3pm on Friday 3 August, the secondary state rolling sum period is from 1pm on Thursday 2 August (covering the last 1 day and 2 hours). Any evaluations relating to that sample interval's secondary state rolling sum period conditions must fall within that time.<\/p>\n

Operating Envelope<\/h3>\n

Defines whether the maximum or minimum operation envelope is used for all conditions of the process.<\/p>\n

    \n
  • If a minimum operating envelope is used, then excursions occur when values drop below a defined limit.<\/li>\n
  • If a maximum operating envelope is used, excursions occur when values exceed the defined limits.<\/li>\n<\/ul>\n

    Primary State Limit<\/h3>\n

    The primary limit must be set for the process to work.<\/p>\n

    If the configured primary state limit is breached, a primary event occurs, and a primary state is reached.<\/p>\n

    The following chart demonstrates a breach of the primary limit, causing a primary event to occur. The operating envelope is set to minimum.<\/p>\n\n\n\n
    <\/td>\n Data Item
    \n Primary Limit
    \n Sample Interval
    \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
    <\/td>\nData is below the primary limit. A default state is reached, and a default<\/strong> event is raised.<\/td>\n<\/tr>\n
    <\/td>\nData is above the primary limit. A primary state is reached, and a primary<\/strong> event is raised.<\/td>\n<\/tr>\n
    <\/td>\nData is below the primary limit. A default state is reached, and a default<\/strong> event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Secondary State<\/h3>\n

    There are several ways to reach the secondary state outcome, in the Process Variable Surveillance process:<\/p>\n

      \n
    • Limit<\/li>\n
    • Duration<\/li>\n
    • Integration<\/li>\n
    • Rolling Sum Total Duration<\/li>\n
    • Rolling Sum Total Integration<\/li>\n
    • Rolling Sum Total Breach Occurrences<\/li>\n<\/ul>\n

      You can choose to set one or more conditions to set the secondary state.<\/p>\n

      For example, a test may have a variable secondary limit defined, as well as configured variables for determining secondary state rolling sum breach occurrences.<\/p>\n

      Secondary State Limit<\/h4>\n

      If the configured secondary limit is breached, a secondary event occurs, and a secondary state is reached.<\/p>\n

      The graph demonstrates a breach of the secondary limit (with an Operating Envelope of Maximum), causing a secondary event to occur.<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Secondary Limit
      \n Sample Interval
      \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
      <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Secondary State Duration<\/h4>\n

      Monitor for a specified continuous duration of the primary state.<\/p>\n

      If the primary state endures for longer than specified in the secondary state duration limit, a secondary event occurs, and a secondary state is reached.<\/p>\n

      The graph demonstrates how the duration of the primary limit causes a secondary event to occur:<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Primary State Duration
      \n Primary State
      \n Secondary Limit
      \n Secondary State Duration Limit
      \n Sample Interval
      \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
      <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nThe continuous primary state duration exceeds the secondary state duration limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Secondary State Integration<\/h4>\n

      Monitor the data integral (from the primary limit as a base) while data is continuously in the primary state, for transgression against a configured limit.<\/p>\n

      The integral is calculated as the area under the data line, between a data point and its preceding data point if both data points are above the primary limit, as shown in the diagram below:<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Primary State Integration
      \n Sample Interval
      \n Trigger Interval
      \n Data Point
      \n Calculating Data from one point backwards to the previous point.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      An explanation of whether or not the different segments are used in integration.<\/p>\n\n\n\n\n\n\n\n
      <\/td>\nData points in this segment fall below the primary limit, therefore there is no integration.<\/td>\n<\/tr>\n
      <\/td>\nThe first data point in this segment falls below the primary limit, therefore there is no integration.<\/td>\n<\/tr>\n
      <\/td>\nIn this segment, data points and their respective preceding data points are above the primary limit, therefore there is integration.<\/td>\n<\/tr>\n
      <\/td>\nFor this segment, the data point is below the primary limit, even though its preceding data point is above the limit, therefore there is no integration.<\/td>\n<\/tr>\n
      <\/td>\nAll data points in this segment fall below the primary limit, therefore there is no integration.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      If the integral exceeds the configured secondary state integration value, a secondary event occurs, and a secondary state is reached.<\/p>\n

      The following graph demonstrates the data integral exceeding the secondary state integral limit.<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Primary State Total Integral
      \n Primary State Integration
      \n Secondary State Integral Limit
      \n Sample Interval
      \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
      <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nThe total primary state integral exceeds the secondary state integration limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Secondary State Rolling Sum Total Duration<\/h4>\n

      Monitor for a specified accumulated duration of all periods of primary state within the preceding specified secondary state rolling sum period.<\/p>\n

      If the accumulated duration of all primary states within the rolling sum period is longer than the specified secondary state rolling sum total duration, a secondary event occurs, and a secondary state is reached. Note how each sample interval has its own rolling sum period.<\/p>\n

      The following chart demonstrates how a secondary state can be reached by secondary state rolling sum duration.<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Primary State Accumulated Duration
      \n Primary State\u00a0
      \n Secondary Rolling Sum Duration Limit
      \n Sample Interval
      \n Trigger Interval
      \n Secondary State Rolling Sum Period
      \n Previous Rolling Sum Period
      \n Next Rolling Sum Period<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n\n
      <\/td>\nData falls below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nThe primary limit is exceeded. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData falls below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nThe primary limit is exceeded. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nThe rolling sum accumulated duration over this sample interval\u2019s preceding rolling sum period exceeds the rolling sum duration limit. A secondary state is reached, and a secondary<\/strong> event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Secondary State Rolling Sum Total Integration<\/h4>\n

      Monitor for a specified accumulated integration of all periods of primary state within the preceding specified secondary state rolling sum period.<\/p>\n

      The integral is calculated as the area under the data curve, where both data points are above the primary limit.<\/p>\n

      If the integral exceeds the configured secondary state rolling sum total integration value, a secondary event occurs, and a secondary state is reached.<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Rolling Sum Accumulated Integral
      \n Rolling Sum Integration
      \n Rolling Sum Total Integral
      \n Sample Interval
      \n Trigger Interval
      \n Rolling Sum Period
      \n Previous Rolling Sum Periods
      \n Next Rolling Sum Period<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n\n
      <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nIn the preceding secondary state rolling sum period, the secondary rolling sum accumulated integral exceeds the secondary state rolling sum total integral limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Secondary State Rolling Sum Breach Occurrences<\/h4>\n

      Monitor whether a set number of values has traversed the configured breach limit, during the preceding specified secondary state rolling sum period.<\/p>\n

      The process counts the number of times that the secondary state rolling sum breach limit is breached within a secondary state rolling sum period. If this number is equal to the secondary state rolling sum breach occurrences number, and if the current state is primary, a secondary event occurs, and a secondary state is reached.<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Secondary State Breach limit
      \n Sample Interval
      \n Trigger Interval
      \n Rolling Sum Period
      \n Previous Rolling Sum Periods
      \n Next Rolling Sum Periods
      \n Breach Occurrences Counter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
      <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData has traversed the breach limit three times during the preceding rolling sum period. In this example, the secondary state breach occurrences is set to 3. Thus, a secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following scenario demonstrates how the current value of the data item does not need to be over the secondary state breach limit in order for the secondary state to be triggered.<\/p>\n\n\n\n
      <\/td>\n Data Item
      \n Primary Limit
      \n Secondary State Breach limit
      \n Sample Interval
      \n Trigger Interval
      \n Rolling Sum Period
      \n Previous Rolling Sum Periods
      \n Next Rolling Sum Periods
      \n Breach Occurrences Counter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
      <\/td>\nData is below the primary limit. A default State is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
      <\/td>\nData is above the secondary state breach limit. In this example, secondary state breach occurrences is set to 1. Because the current state is default and the data is over the primary limit, a primary state is reached, and a primary <\/strong>event is raised. This follows the State Transition Rules, whereby the state cannot transition from default to secondary.<\/td>\n<\/tr>\n
      <\/td>\nData has traversed the breach limit once during the preceding rolling sum period. In this example, secondary state breach occurrences is set to 1.\u00a0
      \nThus, a secondary state is reached, and a secondary <\/strong>event is raised, even though the data is currently below the secondary state breach limit. The transition from primary state to secondary state is allowable according to the state transition rules.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Tertiary State<\/h3>\n

      There are several ways to reach the tertiary state outcome, in the Process Variable Surveillance process:<\/p>\n

        \n
      • Limit<\/li>\n
      • Duration<\/li>\n
      • Integration<\/li>\n
      • Rolling Sum Total Duration<\/li>\n
      • Rolling Sum Total Integration<\/li>\n
      • Rolling Sum Total Breach Occurrences<\/li>\n<\/ul>\n

        Depending on the complexity required, you can set one or more conditions to set the tertiary state. For example, a test may have a variable tertiary limit defined, as well as configured variables for determining tertiary state rolling sum breach occurrences.<\/p>\n

        Tertiary State Limit<\/h4>\n

        If the configured tertiary limit is breached, a tertiary event occurs, and a tertiary state is reached.<\/p>\n

        The following chart demonstrates a breach of the tertiary limit (with an Operating Envelope of Maximum), causing a tertiary event to occur:<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Secondary Limit
        \n Tertiary Limit
        \n Secondary State Breach limit
        \n Sample Interval
        \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        The following events are depicted in the graph:<\/p>\n\n\n\n\n\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the tertiary limit. A tertiary state is reached, and a tertiary<\/strong> event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Note: In this example, the state has transitioned from primary to tertiary. This transition is allowed when the tertiary limit has been breached, according to the State Transition Rules.<\/p>\n

        Tertiary State Duration<\/h4>\n

        Monitor for a specified continuous duration of the secondary state.<\/p>\n

        If the secondary state endures for longer than specified in the tertiary state duration limit, a tertiary event occurs and a tertiary state is reached.<\/p>\n

        The following graph demonstrates how the duration of the secondary state causes a tertiary event to occur:<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Secondary Limit
        \n Secondary State Duration
        \n Tertiary State Duration Limit
        \n Secondary State
        \n Sample Interval
        \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary<\/strong> event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe continuous secondary state duration exceeds the tertiary state duration limit. A tertiary state is reached, and a tertiary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Tertiary State Integration<\/h4>\n

        Monitor the data integral (from the primary limit as a base) while data is continuously in the secondary state, for transgression against a configured limit.<\/p>\n

        The integral is calculated as the area under the data line, only if both data points are in a secondary state, as shown in the diagram below:<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Secondary Limit
        \n Primary State Integration
        \n Sample Interval
        \n Trigger Interval
        \nData Point
        \n Calculating data from one point backwards to the previous point.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        An explanation of whether or not the different segment are used in integration.<\/p>\n\n\n\n\n\n\n\n
        <\/td>\nData points in this segment fall below the secondary limit, therefore there is no integration.<\/td>\n<\/tr>\n
        <\/td>\nThe first data point in this segment falls below the secondary limit, therefore there is no integration.<\/td>\n<\/tr>\n
        <\/td>\nIn this segment, data points and their respective preceding data points are above the secondary limit, therefore there is integration (calculated from the primary limit as a base).<\/td>\n<\/tr>\n
        <\/td>\nFor this segment, the data point is below the primary limit, even though its preceding data point is above the limit, therefore there is no integration.<\/td>\n<\/tr>\n
        <\/td>\nAll data points in this segment fall below the primary limit, therefore there is no integration.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        If the integral exceeds the configured tertiary state integration value, a tertiary event occurs and a tertiary state is reached.<\/p>\n

        The following graph demonstrates the data integral exceeding the tertiary state integral limit.<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Secondary Limit
        \n Secondary State Total Integral
        \n Tertiary State Integral Limit
        \n Secondary State Integration
        \n Sample Interval
        \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe total secondary state integral exceeds the secondary state integration limit. A tertiary state is reached, and a tertiary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Tertiary State Rolling Sum Total Duration<\/h4>\n

        Monitor for a specified accumulated duration of all periods of secondary state within the preceding specified tertiary state rolling sum period.<\/p>\n

        If the accumulated duration of all secondary states within the rolling sum period is longer than specified in the tertiary state rolling sum total duration, a tertiary event occurs and a tertiary state is reached. Note how each sample interval has its own rolling sum period.<\/p>\n

        The following graph demonstrates how a tertiary state can be reached by tertiary state rolling sum duration.<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Secondary Limit
        \n Secondary State Accumulated Duration
        \n Rolling Sum Duration Limit
        \n Secondary State
        \n Sample Interval
        \n Trigger Interval
        \n Rolling Sum Period
        \n Previous Rolling Sum Period
        \n Next Rolling Sum Period<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n\n\n\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default<\/strong> event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe primary limit is exceeded. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe secondary limit is exceeded. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default<\/strong> event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe primary limit is exceeded. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe secondary limit is exceeded. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nThe rolling sum accumulated duration over this sample interval\u2019s preceding rolling sum period exceeds the rolling sum duration limit. A tertiary State is reached, and a tertiary<\/strong> event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Tertiary State Rolling Sum Total Integration<\/h4>\n

        Monitor for a specified accumulated integration of all periods of secondary state within the preceding specified secondary state rolling sum period.<\/p>\n

        The integral is calculated as the area under the data curve, for periods of secondary state.<\/p>\n

        If the integral exceeds the configured tertiary state rolling sum total integration value, a tertiary event occurs and a tertiary state is reached.<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Secondary Limit
        \n Rolling Sum Accumulated Integral
        \n Rolling Sum Integration Limit
        \n Rolling Sum Total Integral
        \n Sample Interval
        \n Trigger Interval
        \n Rolling Sum Period
        \n Previous Rolling Sum Periods
        \n Next Rolling Sum Period<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n\n\n
        <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary <\/strong>event is raised. The integral is calculated from this point, until the state changes again.<\/td>\n<\/tr>\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary <\/strong>event is raised. The integral is calculated from this point, until the state changes again.<\/td>\n<\/tr>\n
        <\/td>\nIn the preceding tertiary state rolling sum period, the tertiary rolling sum accumulated integral exceeds the tertiary state rolling sum total integral limit. A tertiary state is reached, and a tertiary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Tertiary State Rolling Sum Breach Occurrences<\/h4>\n

        Monitor whether a set number of values has traversed the configured breach limit, during the preceding specified tertiary state rolling sum period.<\/p>\n

        Counts the number of times that the tertiary state rolling sum breach limit is breached within a tertiary state rolling sum period. If this number is equal to the tertiary state rolling sum breach occurrences number, and if the current state is secondary, a tertiary event occurs and a tertiary state is reached.<\/p>\n\n\n\n
        <\/td>\n Data Item
        \n Primary Limit
        \n Tertiary State Breach limit
        \n Secondary Limit
        \n Sample Interval
        \n Trigger Interval
        \n Rolling Sum Period
        \n Previous Rolling Sum Periods
        \n Next Rolling Sum Period
        \n Breach Occurrences Counter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n
        <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n
        <\/td>\nData has traversed the breach limit twice during the preceding rolling sum period. In this example, the tertiary state breach occurrences is set to 2. Thus, a tertiary state is reached, and a tertiary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Additional Scenarios<\/h3>\n

        This section describes scenarios that are more complex than the ones previously shown. The Process Variable Surveillance process is capable of assessing multiple conditions, whilst still following the state transition rules.<\/p>\n

        Multiple Ways to Reach a State<\/h4>\n

        This example demonstrates how a secondary state is reached in 3 different ways:<\/p>\n

          \n
        • Secondary State Limit<\/li>\n
        • Secondary State Duration<\/li>\n
        • Secondary State Rolling Sum Breach Occurrences<\/li>\n<\/ul>\n

          The conditions are configured as follows:<\/p>\n

          Primary State<\/p>\n

            \n
          • Operating Envelope<\/strong>: Maximum is selected.<\/li>\n
          • Primary State Limit<\/strong>: A fixed limit, set at 35.<\/li>\n<\/ul>\n

            Secondary State<\/p>\n

              \n
            • Secondary State Limit<\/strong>: A fixed secondary state limit is set at 50.<\/li>\n
            • Secondary State Duration<\/strong>: A fixed secondary state duration limit is set at 5 minutes.<\/li>\n
            • Secondary State Rolling Sum Breach Occurrences<\/strong>:\n
                \n
              • Rolling Sum Period is set at 1 hour.<\/li>\n
              • A fixed breach limit is set at 40.<\/li>\n
              • Breach occurrences is set to 2.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n

                <\/p>\n\n\n\n
                <\/td>\n Data Item
                \n Primary Limit
                \n Primary State
                \n Primary State Duration
                \n Secondary Limit
                \n Secondary State Breach limit
                \n Secondary State Duration Limit
                \n Sample Interval
                \n Trigger Interval
                \n Rolling Sum Period
                \n Next Rolling Sum Periods
                \n Breach Occurrences Counter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                The following events are depicted in the graph:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
                <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nThe continuous primary state duration exceeds the secondary state duration limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData has traversed the breach limit twice during the preceding rolling sum period. In this example, the Secondary State Breach Occurrences value is set to 2. Thus, a secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\n<\/tr>\n
                <\/td>\nData is above the secondary limit. A secondary state is reached, and a secondary <\/strong>event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                Demonstrating Allowable State Changes<\/h4>\n

                The following graph shows how states cannot change unless the State Transition Rules are followed.<\/p>\n

                <\/p>\n

                The graph demonstrates a breach of the secondary limit (with an Operating Envelope of Maximum), causing a secondary event to occur:<\/p>\n\n\n\n
                <\/td>\n Data Item
                \n Primary Limit
                \n Secondary Limit
                \n Tertiary Limit
                \n Sample Interval
                \n Trigger Interval<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n\n\n\n\n\n\n
                 <\/td>\nThe following events are depicted in the graph<\/strong>:<\/td>\nState transition rule affecting state outcome<\/strong>:<\/td>\n<\/tr>\n
                <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\nAny state can move to the default state.<\/td>\n<\/tr>\n
                <\/td>\nData is above the tertiary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\nDefault to tertiary is not allowed. Default can transition to the primary state.<\/td>\n<\/tr>\n
                <\/td>\nData is above the tertiary limit. A tertiary state is reached, and a tertiary <\/strong>event is raised. Note that the data has not changed, but a new state is reached at this interval.<\/td>\nTransition from primary state to tertiary state is allowed where the tertiary limit is in breach (and for no other conditions).<\/td>\n<\/tr>\n
                 <\/td>\nAt the next few sample intervals, there are no events, and the tertiary state persists.<\/td>\nA state cannot move to a lower state, unless it moves to a default state.<\/td>\n<\/tr>\n
                <\/td>\nData is below the primary limit. A default state is reached, and a default <\/strong>event is raised.<\/td>\nAny state can transition to the default state.<\/td>\n<\/tr>\n
                <\/td>\nData is above the primary limit. A primary state is reached, and a primary <\/strong>event is raised.<\/td>\nTransition from default state to primary state is allowed.<\/td>\n<\/tr>\n
                <\/td>\nData is above the tertiary limit. A tertiary state is reached, and a tertiary <\/strong>event is raised.<\/td>\nTransition from primary state to tertiary state is allowed where the tertiary limit is in breach (and for no other conditions).<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
                \n

                Adding a Process Variable Surveillance Process<\/h2>\n

                The Process Variable Surveillance Process compares process variable data against defined limits and conditions. If a limit or condition is breached when the process is executed, a new state is reached and an event is raised.<\/p>\n

                Setting Process Limits<\/h3>\n

                Part of setting up the Process Variable Surveillance process involves selecting limits, such as the primary limit, secondary state limit, tertiary limit, breach limits and so on. Limits can either be fixed values, or they can be variable data taken from entities.<\/p>\n

                The following limits are available. Select a limit type from the drop-down list, then type in or select a limit.<\/p>\n