Diagnostic Tables

Default factory theme

A useful Theme is supplied: "Run Diagnostics".

The theme can be loaded by pressing "Load" in the Properties and Themes dialog. Go the Factory default and choose "Run Diagnostics" from the drop-down list.

You can go to different rows in the Layer and Themes and adjust the use of this theme.

The Run Diagnostics theme alters the order in which layers are drawn in order to make issues more visible.

Diagnostic variables in the Thematics and SQL Tool

These diagnostic variables are closely related to values seen in the diagnostic tables. This relationship is indicated below.

• Nodes
  • Log: Non convergent solution-Max Abs Err
  • Log: Non convergent solution failures (count)
  • Log: Snapshot failures-percentage
  • Log: Suppressed flow (count of occurrences)
• Reservoirs - see list for nodes, and also:
  • Log: Reservoir Event Type, which may be Deficit or Overflow
  • Log: Suppressed flow (count of occurrences)
  • Log: Non convergent solution-Max Abs Err
  • Log: Non convergent solution failures (count)
  • Log: Snapshot failures-percentage
• Transfer nodes
  • Log: Suppressed transfer flow (count of occurrences)
  • Log: Non convergent solution-Max Abs Err
  • Log: Non convergent solution failures (count)
  • Log: Snapshot failures-percentage
• Valves
  • Log: Valve not regulating (% of time)
  • Log: Valve showing unreliable regulation (% of time)
  • Log: unstable continuous regulators
• Pump Stations
  • Log: Zero flow
  • Log: Flow above pump cure
  • Log: number of starts

Snapshots

• This table lists each "Snapshot number" and "Date/Time". For each snapshot the "Status" column indicates whether convergence achieved.
  • Status = Flow balance - This means that the Engine has found convergence within required limits.
  • Status = No flow balance - Indicates that the Engine cannot approach a solution.
    Note: The relevant settings are in the Run Dialog. The Engine was required to achieve flow balance within a number of iterations "maximum iterations per timestep", and to achieve an error no larger than "computational accuracy".
  • Status = Flow balance achieved but regulation not achieved -This may be seen if the simulation option "Enforce Valve/PST regulation tolerance" option is selected in the Simulation Options dialog. In this case the Engine may attempt to further reduce errors, and it may expend many more snapshots for this error reduction. If flow balance has been achieved, then the engine will allow further iterations; it will use up to ten times the maximum number of iterations to reduce errors. (Tolerance for valves is set on a per-valve basis in the valve control properties. Tolerance for pumps is set globally for pumps in Sim options.)
• "Total iterations" used by the snapshot. Flow balance errors will arrest a snapshot earlier than regulator errors.
• The "Node ID" with the worst error in that snapshot is identified, along with the size of the Error for that asset.

How to use this information:

• In summary, there are two reasons why snapshot failure is shown in this table. The most serious kind of error is that flow balance cannot be achieved. The lesser error is that flow errors are not below the required computational accuracy.
• If flow balance cannot be achieved, or if computational accuracy is not achieved, then the relevant snapshot's results are less trustworthy. Further, the subsequent course of the simulation cannot be fully trusted.
• You should look at nodes with serious errors and consider assets in their immediate vicinity (pumps and valves) and aim to identify reasons for failure. You might wish to accept a less stringent computational accuracy for flow.

Snapshot Failures

• This page describes the node that has the worst failure in each snapshot. For each node listed, the table reports the number of snapshots for which that node gave the worst error.
• This is a different way of expressing the information in the snapshot failures table.

How to use this information:

• This table will draw your attention to th3 nodes that are associated with the most unreliable parts of the model. A good starting point for improving stability could be to examine pumps and valves near these nodes.

Non convergent solution

• The table lists nodes where a non-convergent snapshot is recorded. It includes the number of failed snapshots observed for the node, and the size of errors.
• This table expresses information similar to the Snapshot and Snapshot Failures pages.

How to use this information:

• This table will draw your attention to the nodes that are associated with the most unreliable parts of the model. A good starting point for improving stability could be to examine pumps and valves near these nodes.

Unstable continuous regulators

• This page lists the valves that are unstable and the number of snapshots on which they show instability.
• The threshold for defining instability is the valve's "Regulation Precision (%)" setting.

How to use this information:

• Valves that show instability should be examined closely. Look at valve profiles and valve curves and consider if these are correct.

Valve regulation unreliable

• This table lists valves the operate at the extremes of their curves and so they may be unstable.
• This poor behavior may happen for a portion of simulation time. Time periods are given in minutes and are expressed as percentage of the whole simulation. Also, these "poor periods" are summarized for six-hour sections of the day.

How to use this information:

• Valves that are at the extremes of their capabilities should be examined closely. Look at valve profiles and valve curves and consider if these are correct.

Valve Not Regulating

• The table list valves that are fully open and so not acting as regulators.
• This non-regulation behavior may happen for a portion of the simulation time. The table gives this total and expresses it as a percentage. The table also divides the day into four periods of six hours, and it shows the total non-regulating time in each period.

How to use this information:

• Valves that are not regulating may not be behaving as intended. Look at valve profiles and valve curves and consider if these are correct.

Pump Stations

• This table lists pumps that shows summaries of behavior, and also a variety of potentially undesirable behaviors.
  • The pump's running period and the number of times the pump starts are shown. These values may be intended but it is worth reviewing them. A large number of starts may be undesirable.
  • The "Zero flow" and "Flow above pump curve" columns indicate the number of times that a pump is operating beyond the limits of its pump curve.

How to use this information:

• When observing this table, it is advised to look in the Pump Off Curve table, also, to get detailed information on events relating to the pump curve.
• Give close attention to pumps that are operating at the extremes of their pump curves. Behavior may unstable or unintentional.

Pump Off Curve

• This table lists, in detail, the times when each pump reaches the edge of its specified operating conditions. The following general errors may occur:
  • Head is too high.
  • Flow is greater than the range of the pump curve.

How to use this information:

• This table can be used in conjunction with the Pump Stations table. The characteristics of pumps should be reviewed to ensure a stable and accurate simulation.

WQ Improvements

• The table lists information about timesteps for water quality runs.
• The table shows, for each timestep, how many pipes require a shorter timestep, and a recommendation for that time step.

How to use this information:

• Use this information to understand throughout the simulation how many pipes need a smaller timestep and what that value should be.

Reservoir Events

• Reservoirs may show two kinds of "unsatisfactory" behavior: Overflow (loss of water) or Deficit (apparent creation of water).
• The table lists the volume of water lost or gained, and the number of minutes over which these losses and gains occur.

How to use this information:

• Overflow and Deficit indicate an unsatisfactory behavior in the model and should be examined.

Suppressed Totals

• This table gives a list of objects where demand flow or transfer flow cannot be supplied.
• The table gives the Object ID. the type of flow that is suppressed and the number of occasions when this happens.
• The type of suppressed flow may be:
  • Demand Flow (nodes or reservoirs).
  • Transfer Flow (transfer nodes).

How to use this information:

• You should review the occasions on which flow out of the system is suppressed. The system may not be acting as you expect.
• Use this table in conjunction with the Suppressed Demand Detail and Suppressed Transfer Detail tables.

Suppressed Demand Detail

• This table lists the object (Node or Reservoir) that experiences suppressed demand. It gives the time of the suppression and the value of lost flow.

How to use this information:

• If demand flow is suppressed, then your system may not be behaving as expected.

Suppressed Transfer Detail

• This table lists the Transfer node that experiences suppressed transfer flow. It gives the time of the suppression and the value of lost flow.

How to use this information:

• If transfer flow is suppressed, then your system may not be behaving as expected.