tf^AL LADJRATOIIY, 1 



FACULTY OF APPLIED SCIENCE. \ 



g_BJ CIRCLE DIAGRAM. 285 



not necessary to calculate their values in watts, which may prove 

 a convenience. 



20. Torque. Torque is equal to the secondary input divided 

 by the synchronous speed; see 54, Exp. 8-A. The secondary 

 input, in Fig. I, is seen to be SP, being the primary input MP, 

 less the no-load losses MN and primary copper loss NS. 



21. In synchronous watts, torque is equal to SP, in watts, 

 divided by the synchronous speed of the motor in revolutions 

 per minute. 



If this is multiplied by 7.04, we have the torque in pounds at 

 one foot radius. (Compare 3b, Exp. 2-A.) 



To get torque in synchronous horse-power, SP is measured in 

 horse-power and divided by the synchronous speed in revolutions 

 per minute. 



22. The maximum or " pull-out " torque is seen to occur at 

 P Q where a tangent to the circle is parallel to AG. The maxi- 

 mum occurs at such a slip, s, that R 2 = sX 2 ; ga, Exp. 8-A. 



23. Ratios. The following results, being ratios usually ex- 

 pressed as percentages, are independent of scale. They may be 

 found by division, or graphically as in Appendix I. 



24. Power Factor. The power factor at an^ load is equal 

 to CO divided by OP ; it is a maximum at F 4 , where a line from 

 O is tangent to the circle. 



25. Efficiency. The efficiency is equal to the output divided 

 by the input, namely, KP divided by MP. 



26. Slip. The slip is equal to the secondary copper loss, 

 divided by the secondary input (see 54, 54a, Exp. 8-A) ; 

 namely, SK divided by SP. 



