How does the screw turbine connect to the grid?

  1. Assume the grid power is down.
  2. Grid power comes back on.
  3. Time delay relay in our controls waits 6 minutes to turn our control panel on.
  4. Panel verifies that frequency and voltage of the grid are okay.
  5. If frequency and voltage are okay, the panel releases the turbine brake .
  6. Automated sluice gate then starts to open to let water to the screw and the screw starts to turn.
  7. When the control panel sees the generator (not the screw) is turning at 1800 rpm (60 Hz, 4 pole motor), it then connects the generator to the grid. The generator just starts to generate at 1801 rpm.
  8. If the frequency or voltage of the grid are outside set parameters, the controls will turn off the generator by engaging the brake and disconnecting the contactor and closing the sluice gate.
  9. If the grid goes down again, (the contactor is diconnected), the brake is engaged and the sluice gate closes.