812 INDEX 



O 



PAGE 



Oil, lubricating 198, 338, 341 



transformer 45, 178, 443, 449, 451 



Oil circuit breakers 496 



bushings - 505 



rating 497 



rupturing capacity '. . .' 470, 497 



selection of type 497 



structures 563 



time of opening 470, 498 



types and design 498 



Oil circuit-breaker batteries 589 



Oil production in United States 15 



Organization and Operation 746 



management 746 



operating force 746 



operating and maintenance instructions 754 



operating records 748 



Oscillations 596 



Outdoor stations 192, 577 



Overspeed of turbines 226 



Over-voltage protection 593 



arcing ground suppressor 613 



classification of over-voltages 593 



lightning arresters 604 



protection of telephone lines 620 



short-circuit suppressor 620 



P 



Parallel operation, generators 318 



transformers 421 



Penstocks. See Pipe lines 114 



Perimeter, wetted 107 



Piezometers 793 



Piping, lubricating oil 339, 343 



transformer oil 456 



transformer cooling water 457 



Pipe lines 114 



anchors 128 



concrete pipe 137 



economic diameter 121 



expansion joints 128 



friction loss ' 116 



gradient 119 



loss of head 116 



number 120 



pressure 126, 246, 250 



