PROBLEMS. 405 



Each coarse wire coil, S, consists of 100 turns of two num- 

 ber seven wires in parallel (B. & S.). Length of mean turn 9^ 

 inches. 



/ = 5 inches, g f = \ inch, F'= f inch (fine wire coil), X'=\ 

 inch (coarse wire coil), and X= lof inches. 



The net sectional area of the iron core is 3.7 square inches, 

 the mean length of the magnetic circuit is 22 inches, and the 

 volume of the iron is 81.4 cubic inches. Thickness of lamina- 

 tions 14 mils. 



124. Find the two components M p and M w of the magnetiz- 

 ing current of each of the above transformers, E f being 1,100 

 volts at 1 3 3 cycles per second. Parts of coils in core-type trans- 

 former being connected in series (N r = 2,000, N ff 200). 



125. Calculate the leakage inductance of each of the above 

 transformers, parts of coils of core-type transformer being con- 

 nected in series. 



126. Determine the regulation of the above shell-type trans- 

 former when it takes current from i,ioovolt 133 cycle mains 

 and delivers current to a receiving circuit of which the resistance 

 is 1.25 ohms and the reactance is 1.3 ohms. 



127. Determine the regulation of the above core-type trans- 

 former when it takes current from 1,100 volt 133 cycle mains 

 and delivers current to a receiving circuit of which the resistance 

 is 1.25 ohms and the reactance is 1.3 ohms. 



CHAPTER XII. THE INDUCTION MOTOR. 



128. The winding of an ordinary ring-wound direct-current 

 armature has 24 sections. These sections are disconnected from 

 the commutator and numbered in order from I to 24. Specify 

 the manner in which these 24 coils are to be connected to two- 

 phase mains to produce in the ring a rotating state of magnetism 

 with four poles, with six poles, and with twelve poles. Specify 

 the connections of the 24 coils to three-phase mains to produce 

 in the ring a rotating state of magnetism with two poles, with 

 four poles, and with eight poles. State the speed of the mag- 



