461 



rvu c PAGE 



Ohm, unit of resistance, definition of m 



Ohm'slaw ....................... 



Operation of generator, principle of ......... ....... 24 



of generators in parallel .................... 142-146 260 



of motor, principle of .................. 



Output, calculation of possible, for a c-c. machin e ........ ..... 99 



relative values of, for a given armature used as c-c. 



generator and synchronous converter ............... 379 



Over-compound generator, operation of ............... 134 



use of shunt for series field on ....... 108 



Over-load release .................................... 174 



Pancake coil, use of in transformer ........................ 283 



Panel of a switchboard .......................... 424 



Parallel operation of a-c. generators ................. 260 



c-c. generators ....................... 142-146 



Period, meaning of term ............. . ....................... 196 



natural, of an a-c. circuit ............................. 227 



of a synchronous motor ....................... 328 



Permeability, magnetic ...................................... 19 



Phase characteristics of a synchronous motor .................. 316 



Phase displacement of voltage and current ..................... 203 



Physiological effect of an electrical current ..................... 2 



Pitch of armature windings .................................. 84 



Pole shoe, use of ........................................... 35 



Pole tips ................................................... 35 



Poles, oommutating ..................................... 36, 119 



material and construction .......................... 32, 124 



Polyphase circuit, metering pov, r er in a ........................ 404 



machinery compared to single phase ................. 400 



power, advantage over single phase ................. 398 



transformation ............................. 402 



Potential, meaning of the term .............................. 14 



difference of .............. ........................ 14 



Power, active in an a-c. circuit ............................... 205 



Power factor of an a-c. circuit ................................ 204 



Power, formula for, in a c-c. circuit ........................... 13 



in an a-c. circuit .......................... 204 



, measurement of, in an a.c. circuit ...................... 208 



reactive, in an a-c. circuit ............................. 204 



unit of ............................................. 13 



"Pump-back" test ......................................... 19 3 



