Operating speed changes for pumps produces transients. A time dependent change in the speed ratio(s) (operating speed/rated speed) may be defined for all types of pumps. A ratio of 1 means the pump is working with the full speed and 0 implies the pump is stopped). The procedure below describes how to assign a curve to a pump:

  1. Click on the Select Menu  button of the Attribute Browser window, and then click on the Select Pump button and select the desired pump in the map window.

  2. Click on the Pump Operation Change  button from the Surge toolbar. The Pump Operation Change Data dialog box appears on the screen.

  3. If no Pump Surge Data has been entered, the only Disturbance Type available for selection is "0:Speed". You can choose either an existing Speed Curve from the drop-down list or click on the Browse button to the right to create a new curve or edit an existing one. The Pump Speed Curve contains a curve of the pump speed factor over the time of the simulation.

  4. If it is necessary to install a bypass line and/or a check valve with the pump, click on the Pump Surge Data button to access the Pump Surge Data dialog box.

Example - The pump is running at full speed (1.0) for 2 seconds and then the speed ramps down to half over the next 2 seconds.