When running as a turbine, the performance of the pump acts very differently than when it was running as a pump:

  • The discharge of the pump becomes the inlet of the turbine and the suction becomes the outlet of the turbine.
  • The pump impeller will turn in the opposite direction and becomes the runner of the turbine.
  • The impeller orientation is the same in both the pump and turbine mode.
  • It is difficult to predict actual the turbine performance of a reverse running pump. You really need specific test data on the pump you intend to use as a turbine, if you want predictable results

The following equation can be used to make an estimate:

Some things to consider when you run the pump as a turbine:

  • You will have a narrow operating band compared to variable nozzle turbines
  • At constant speed, the power developed and efficiency drop to zero at approximately 40% of the hydraulic turbine best efficiency rate of flow.

You will also want to look at:

  • Over speed trip controls
  • Runaway speed possibility
  • The flow rate at runaway speed
  • Abrasives and solids in the fluid.
  • Torque reversals at start-up and shutdown.