{"id":58873,"date":"2023-02-17T15:00:20","date_gmt":"2023-02-17T07:00:20","guid":{"rendered":"https:\/\/oihelp.corporate.ifs.com\/help\/sentinel\/sentinel-processes\/steady-state-process\/"},"modified":"2024-07-09T10:03:07","modified_gmt":"2024-07-09T02:03:07","slug":"steady-state-process","status":"publish","type":"page","link":"https:\/\/oihelp.corporate.ifs.com\/help\/sentinel\/sentinel-processes\/steady-state-process\/","title":{"rendered":"Steady State Detection Process"},"content":{"rendered":"\n

The Steady State Detection evaluates up to four separate data inputs to determine whether the asset under surveillance has reached a steady state. This process can also evaluate whether data is continuously transient, that is: if it does not reach the steady state for longer a specified duration.<\/p>\n

The standard deviation of each input is evaluated at every sample interval. Each input\u2019s standard deviation is calculated over the duration specified for that input, and measured against the deviation threshold specified for that input.<\/p>\n

For example: for Input 1, the process is configured to calculate the standard deviation for all samples collected within the last two hours; it then determines whether this figure exceeds the current deviation threshold value. Simultaneously, the standard deviation for Input 2 for all samples collected over the last hour (Input 2\u2019s configured deviation duration) is evaluated to determine whether it has exceeded the current deviation threshold for Input 2. The combined outcome for all configured inputs is used to determine the test outcome for that sample interval.<\/p>\n

Steady State Detection is used for scenarios where fluctuations of values are expected initially (transient state), but where these variations should subside over time, leading to a steady state.<\/p>\n

If the data continues to fluctuate for one of more of the inputs (that is, if it continues to be in the transient state) for longer than a specified duration, this triggers a continuous transient state.<\/p>\n

\n

State Transition Rules<\/h2>\n

The Steady State Detection process has clearly defined state transition logic paths. Transition from one state to another is 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 Steady State Detection process.<\/p>\n\n\n\n\n\n\n\n
This state can transition to<\/strong><\/td>\n <\/td>\nThis state<\/strong><\/td>\n<\/tr>\n
Transient<\/td>\n<\/td>\nSteady<\/td>\n<\/tr>\n
<\/td>\nContinuous Transient<\/td>\n<\/tr>\n
Continuous Transient<\/td>\n<\/td>\nSteady<\/td>\n<\/tr>\n
Steady<\/td>\n<\/td>\nTransient<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The following diagram outlines the state transition logic of the Steady State Detection process.<\/p>\n\n\n\n
\n

<\/p>\n<\/td>\n

\n

T<\/strong>\u00a0 \u00a0 Transient State
\nCT<\/strong>\u00a0 Continuous Transient State
\nS<\/strong>\u00a0 \u00a0 Steady State<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\n

Test Outcomes<\/h2>\n

A number of outcomes are possible when the Steady State Detection process is executed:<\/p>\n\n\n\n\n\n\n
Steady State<\/strong><\/td>\nFor all inputs, the standard deviation for that input is at or below the input\u2019s deviation threshold.<\/td>\n<\/tr>\n
Transient State<\/strong><\/td>\nFor one or more inputs, the standard deviation for that input is above the input\u2019s deviation threshold.<\/td>\n<\/tr>\n
Continuous Transient State<\/strong><\/td>\nThe transient state persists for up to or longer than the defined continuous transient duration.<\/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
\n

Using Standard Deviation<\/h2>\n

Sentinel uses the statistical standard deviation method to calculate dispersion of the different input values over a given duration.<\/p>\n

\n

Conditional Logic<\/h2>\n

The Steady State Detection 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

Output Status Tag<\/h3>\n

An Output Status Tag can be set for both the Continuous Transient State and the Steady State. In each case, this tag can be an entity attribute, either as it is, or as part of a calculation.<\/p>\n

If an output status tag is set for the continuous transient state, the tag will show a status of one within Explorer when a continuous transient event is raised, and zero for any other state.<\/p>\n

Similar behaviour applies to the output status tag for steady state (showing a status of one for steady state, and zero for any other state). Within the Server Browser, the status tag can be observed, for example altering a shape's appearance to indicate whether the monitor's data item is in a particular state or not.<\/p>\n

Transient State<\/h3>\n

The Transient State can be considered the default state of the Steady State Detection Process.<\/p>\n

Every input is evaluated. If any one of the inputs\u2019 standard deviation is above that input\u2019s deviation threshold, a transient event is raised and the process goes into a transient state.<\/p>\n

The following example demonstrates how a steady state moves to a transient state. Three inputs are used. In this example, the following settings are used:<\/p>\n

    \n
  • All three inputs have fixed deviation thresholds.<\/li>\n
  • All three inputs have a deviation duration of five hours.<\/li>\n
  • The sample interval is 1 hour.<\/li>\n<\/ul>\n\n\n\n
    Data item<\/td>\n Deviation threshold<\/td>\n Sample interval<\/td>\n Standard deviation (calculated for the 5 hours preceding the sample interval)<\/td>\nThe sample interval being reported on.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n\n\n
     <\/td>\n <\/td>\nCollective Evaluation of Inputs<\/strong><\/td>\n<\/tr>\n
    Input 2 <\/strong><\/td>\n At 11:00am <\/strong>the standard deviation for Input 2 goes above the deviation threshold for Input 2.<\/td>\nAt 11:00am <\/strong>one of the three inputs has breached the primary deviation limit. A transient event is raised, and a transient state is reached.<\/td>\n<\/tr>\n
    Input 1<\/strong><\/td>\n At 11:00am<\/strong> the standard deviation for Input 1 is still below the deviation threshold for Input 1. (This input has not caused the transient event.)<\/td>\nAt 11:00am <\/strong>one of the three inputs (Input 2) is above the primary deviation limit.<\/td>\n<\/tr>\n
    Input 3<\/strong><\/td>\n At 11:00am<\/strong> the standard deviation for Input 3 is still below the deviation threshold for Input 3. (This input has not caused the transient event.)<\/td>\nAt 11:00am <\/strong>one of the three inputs (Input 2) is above the primary deviation limit.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Continuous Transient State<\/h3>\n

    A continuous transient event occurs when the transient state persists for up to or longer than the defined continuous transient duration.<\/p>\n

    The following example demonstrates the continued duration of the transient state, which causes a continuous transient event to occur. In this example, the following settings are used:<\/p>\n

      \n
    • Both inputs have a deviation duration of five hours.<\/li>\n
    • The continuous transient state duration is 2 hours.<\/li>\n
    • Both inputs use a fixed deviation threshold.<\/li>\n
    • The sample interval is 1 hour.<\/li>\n
    • \u00a0<\/li>\n<\/ul>\n\n\n\n
      Data item<\/td>\n Deviation threshold<\/td>\n Sample interval<\/td>\n Standard deviation (calculated for the 5 hours preceding the sample interval)<\/td>\nThe sample interval being reported on.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n\n\n
       <\/td>\n <\/td>\nCollective Evaluation of Inputs<\/strong><\/td>\n<\/tr>\n
      Input 2<\/strong><\/td>\n At 11:00am <\/strong>the standard deviation for Input 2 goes above the deviation threshold for Input 2.<\/td>\nAt 11:00am <\/strong>one of the three inputs has breached the primary deviation limit. A transient event is raised, and a transient state is reached.<\/td>\n<\/tr>\n
      Input 2<\/strong><\/td>\n At 1:00pm<\/strong> the standard deviation for Input 2 is still above the standard deviation threshold for Input 2.<\/td>\nAt 1:00pm<\/strong> the transient state has a duration of 2 hours. A continuous transient state is reached, and a continuous transient event is raised.<\/td>\n<\/tr>\n
      Input 1<\/strong><\/td>\n At 1:00pm<\/strong> the standard deviation for Input 1 is still below the standard deviation threshold for Input 1. Therefore, Input 1 has not caused or affected either the transient event or the continuous transient event.<\/td>\nAt 1:00pm<\/strong> the transient state has a duration of 2 hours, due to the continued high standard deviation for Input 2.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Steady State<\/h3>\n

      For all inputs, the standard deviation is at or below that input\u2019s deviation threshold.<\/p>\n

      The following example demonstrates how a transient state changes to a steady state. Three inputs are used. In this example, the following settings are used:<\/p>\n

        \n
      • The sample interval is 1 hour.<\/li>\n
      • Input 2 uses a fixed deviation threshold.<\/li>\n
      • Input 1 and input 3 use variable deviation thresholds.<\/li>\n
      • All three inputs have a deviation duration of five hours.<\/li>\n<\/ul>\n

        In the example, all three inputs have a deviation duration of five hours. For each input, at each sample interval: all samples collected over the previous five hours are used to calculate the standard deviation for that input.<\/p>\n\n\n\n
        Data item<\/td>\n Deviation threshold<\/td>\n Sample interval<\/td>\n Standard deviation (calculated for the 5 hours preceding the sample interval)<\/td>\nThe sample interval being reported on.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n\n\n
         <\/td>\n <\/td>\nCollective Evaluation of Inputs<\/strong><\/td>\n<\/tr>\n
        Input 1<\/strong><\/td>\n At 9:00am<\/strong> the standard deviation for Input 1 goes below the deviation threshold for Input 1.<\/td>\nAt 9:00am<\/strong> one out of three inputs has its standard deviation below its deviation threshold.<\/td>\n<\/tr>\n
        Input 2<\/strong><\/td>\n At 10:00am<\/strong>, the standard deviation for Input 2 goes below the deviation threshold for Input 2.<\/td>\nAt 10:00am<\/strong> two out of three inputs have their standard deviation below their respective deviation thresholds.<\/td>\n<\/tr>\n
        Input 3<\/strong><\/td>\n At 11:00am<\/strong> the standard deviation for Input 3 goes below the deviation threshold for Input 3.<\/td>\nAt 11:00am<\/strong> all three inputs have their standard deviation below their respective deviation thresholds. A steady state is reached, and a steady state event is raised.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
        \n

        Adding a Steady State Detection Process<\/h2>\n

        The Steady State Detection Process evaluates the standard deviation of one or more defined inputs. Based on the combined outcome of these evaluations, a state persists or a new state is raised.<\/p>\n

        Setting Process Values and Limits<\/h3>\n

        Setting up the Steady State Detection process involves selecting inputs and deviation thresholds. Deviation thresholds can either be fixed values, or they can be variable data taken from entities. Inputs can only be defined as variable data taken from entities.<\/p>\n

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

          \n
        • Fixed Value<\/strong>: Type in a numerical value.<\/li>\n
        • Source Tag<\/strong>: This option is only available if the Source Type<\/strong> is Tag<\/strong>.<\/li>\n
        • Attribute<\/strong>: This option is only available if the test\u2019s Source Type<\/strong> is Entity <\/strong>or Hierarchy<\/strong>. Click the ellipsis button to select an attribute of the source entities.<\/li>\n
        • Calculation<\/strong>: Click the ellipsis button to open the Edit Calculation window.\u00a0\n
            \n
          • If the Source Type is Entity<\/strong> or Hierarchy<\/strong>: Type a calculation, prefixed by \u2018this\u2019 as the Source Entity<\/strong> token, for example: {this:THP} + 34<\/strong>.<\/li>\n
          • If the Source Type is Tag<\/strong>: Type a calculation, prefixed by \u2018this\u2019 as the Source<\/strong> Tag<\/strong> token, for example: {this} * 2<\/strong>.<\/li>\n<\/ul>\n<\/li>\n
          • Tag<\/strong>: Click the ellipsis button to select a tag.<\/li>\n
          • Entity Attribute<\/strong>: Click the ellipsis button to select an entity. From here, select an attribute, or attribute value, for the selected entity.<\/li>\n<\/ul>\n

            Adding the Process<\/h3>\n

            As with all Sentinel processes, the Steady State Detection Process is defined within a Sentinel Test<\/strong> page.<\/p>\n

            In the Sentinel Test<\/strong> page:<\/p>\n

              \n
            1. Expand the Process<\/strong> panel.<\/li>\n
            2. Select Steady State Detection<\/strong> from the Process<\/strong> drop-down list.<\/li>\n<\/ol>\n

              \"C:\\Users\\gxl1129\\AppData\\Local\\Temp\\SNAGHTML6c0ba4a7.PNG\"<\/p>\n

              Continuous Transient State<\/h4>\n

              The duration specified here is used to determine the transition from transient state to continuous transient state. An output status tag can reflect this state transition on a Server Browser page.<\/p>\n

              1. Type integer values in the days<\/strong>, hours<\/strong>, mins <\/strong>(minutes), and secs <\/strong>(seconds) Duration <\/strong>boxes to define a duration period. The default value is zero.<\/p>\n

              \"C:\\Users\\gxl1129\\AppData\\Local\\Temp\\SNAGHTML6c0cf235.PNG\"<\/p>\n

              2. Optionally set the Output State Tag.<\/p>\n

                \n
              1. Select the Output Status Tag<\/strong> check box.<\/li>\n
              2. Select one of the options from the drop-down list, then click the ellipsis button to select.\n