The Pump Operational Change Data window is accessed by selecting a pump and selecting the Pump Operation Change button in the Attribute Browser. This function is used to describe the pump/turbine operational changes during transient analysis. A turbine is represented by the pump element with turbine-specific parameters in a surge model. A wicket gate can be specified for the turbine element to simulate the transients due to wicket gate changes.

 

Disturbance Type

Operating speed changes for pumps produce transients. A time dependent change in the speed ratios (operating speed/rated speed) may be defined for all types of the pumps. Pumps can also be tripped (lose power) and the resulting rundown calculated based on the pump and motor inertia and dynamic characteristics described in the Pump File (see Pump File Selector). A trip can be specified with a ratchet, which will prevent reverse rotation. Pump trip and rachet changes require a pump file which is selected in the Pump Surge Data.

There are three types of pump operation changes that can be simulated:

  • Pump Speed - The curve designated in the Speed Curve will dictate the speed of the pump during the surge analysis.

  • Pump Trip - At the Trip Start Time the pump will run down according to the data specified in the pump surge data. Once the pump has lost power it may continue turning (turbining) or be forced to run backwards (reverse turbine).

  • Pump Ratchet - A pump ratchet is a pump trip where there is a one-way bearing installed in the pump. The one way bearing will allow the pump to turbine but will not allow it to spin backwards. The Trip Start Time is the time at which the pump trip will be initiated.

Operating speed changes for turbines and wicket gate opening changes for the associated wicket gate (if applicable) produce transients. A time dependent change in the speed ratio or the wicket gate opening may be defined for turbines. Turbines can also be tripped (lose power) and the resulting rundown is calculated based on the turbine inertia and dynamic characteristics described in the Suter format.

  • Turbine Speed - The curve designated in the Speed Curve will dictate the turbine speed during the surge analysis.

  • Wicked Gate Setting - The curve designated in the Wicked Gate Setting Curve will dictate the wicket gate opening during the surge analysis.

  • Turbine Trip - At the Trip Start Time, the turbine will run down according to the data specified in the pump/turbine surge data.

Speed Curve

Select the name of the curve defining speed change. Select the curve from existing predefined curves or use the Browse button to open the curve editor to create a new curve or edit and existing curve. Select a curve where X = Simulation Time and Y = the Pump Speed Ratio (Operating Speed/Rated Speed).


Wicket Gate Curve

Select the name of the curve defining the wicked gate curve. Select the curve from existing predefined curves or use the Browse  button to open the curve editor to create a new curve or edit and existing curve. Select a curve where X = Simulation Time and Y = percent open.

Trip Start Time

Enter the simulation time when the trip starts. Enter the number of seconds from the start of the simulation to when the pump trip starts.

Purge - Use the Purge button to remove existing Data.

Create/Update - Enter new or changed data and exit the dialog box window.

Cancel - Cancels any new or changed data and closes the dialog box window.