{HEAD ~ A fail safe system} is used in {TAIL ~ a control unit} for opening and closing guide vanes of a pump turbine apparatus operable in both of pump operation mode and turbine operation mode 
is used in
{ HEAD ~ A fail safe system } is used in { TAIL ~ a control unit } for opening and closing guide vanes of a pump turbine apparatus operable in both of pump operation mode and turbine operation mode
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH