Performance Study

A pump performance study is used to compare model values of pump head and efficiency curves with field data from a SCADA system or pump test. It can be accessed by right clicking on a pump in the model and picking Performance Study.

To compare pump head curves, the user must have data on flow and the corresponding pump head for each point. The pump head is calculated as the difference between the measured suction and discharge head. There are two ways to calculate these heads:

Pressure plus elevation of pressure gauge.
Level plus reference elevation. Reference is usually the elevation of the bottom of the tank (or whatever elevation correspond to zero level).

Submersible pumps do not have a suction pressure so the level of water in the suction tank is used as the suction head.

If a comparison of pump efficiency is also desired, it is necessary to provide data for power. In most cases, this will be the electrical (wire) power and the value displayed will be the wire-to-water efficiency.

The dialog for entering the data is shown below:

Page 1 – Performance Study Settings

After starting the pump performance study, the user will see the dialog above. The performance study requires configured SCADA signals to retrieve data from the SCADA system. Only historical SCADA data is supported.

Note: If there are no SCADA signals configured, the user can click on the […] button next any of the signal fields in the dialog. This will open the SCADA Signals dialog. See SCADA Signals on how to configure signals.

Note: To find SCADA signals more easily, click on the Find button to the right of each SCADA Signal field. The find signal dialog will open. Enter in a string to search for signals containing that value. Once found, select it in the results list and click OK.

The performance study provides a flexible way of using multiple formats of SCADA data. If SCADA data provides both suction and discharge pressures, then select the appropriate signals for suction and discharge pressure.

Data Type defines whether the suction and discharge head are based on a pressure gauge reading or a wet well level.

If the SCADA data has discharge pressure data but the suction data is recorded as a tank level, then change the Data Type for suction to Level. Enter the elevation of the suction signal. For the discharge pressure, enter in the gauge elevation of the pressure gauge.

The gauge elevation is initialized to the pump’s elevation. Using an accurate elevation for both fields is key to calculate the correct head. Level reference elevation is the elevation corresponding to the zero value for level (depth) in a tank or wet well.

If the level is known as the distance below a known level (e.g. the distance to the water surface from the ground in a well), then the ground elevation is entered as the Elevation and the level would be a negative number since it is the vertical distance below the ground.

The user can also calculate the efficiency of the pump using power data from SCADA. To calculate efficiency from SCADA data, the user must check the Compute Efficiency box. This requires a signal representing the power. The power is assumed to be in kilowatts.

Not all pump data needs to come from the SCADA system. In some cases, a pump test is conducted where the flow is adjusted by throttling valves to and the corresponding heads and power are measured. If the user has data for a pump test but the data is not time stamped, the user can simply enter any valid time stamp data in a field in the file (e.g. Excel file) and this time stamped data is not displayed in the graphs (but only in a tool tip).

Validation

When the user clicks the Next button to continue to the next page, the settings are checked for validity. Signal selection for flow, suction pressure and discharge pressure are required. If Level is specified as the data type, then the level signal is required. If data are missing or invalid, then the user is presented with a message stating what data is missing or invalid.

If the user opts to compute the efficiency, the power signal selection is required.