318 / | HD | ELECTRICITY: MOTIVE POWER SYSTEMS |
700 | DF | SYNCHRONOUS MOTOR SYSTEMS {7} |
705 | DF | .~ Synchronization systems {4} |
706 | DF | .~.~ With armature power removal upon failure to synchronize or loss of synchronism {2} |
708 | .~.~.~ Responsive to thermal electrical element in system |