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