286 



APPENDIX B 



TABLE B SINGLE-PHASE AND THREE-PHASE SYNCHRONOUS 

 MOTORS OF AMERICAN MANUFACTURE 



All these machines have rotating poles and open slot stationary 

 armatures. The field-poles are equipped, in addition to the standard 

 field-coils, with a short-circuited winding similar to an induction- 

 motor, which is utilized to make the machine self-starting as an 

 induction-motor, and also as a " damper " to prevent " hunting " 

 when running in synchronism. When starting, polyphase machines 

 will develop from 20 to 50 per cent of their normal torque with 

 from 100 to 250 per cent of the normal input in kilovolt-amperes. 

 The single-phase machines are not self-starting. 



