32 PROBLEMS IN ALTERNATING CURRENT MACHINERY 



that the current is lagging and has a value of 0.80 of its maximum 

 value in any phase when that phase is opposite the center of 

 the poles. 



42. A 25-cycle alternating-current generator has an armature 

 core with slots that are 1 .35 in. wide and 2.625 in. deep. There are 

 four inductors in series per slot, (a) Calculate the slot reactance 

 per inch of slot on the assumptions that the path of the leakage 

 flux across the inductors is parallel to the bottom of the slot, 

 that the permeability of the iron is great and that the inductors 

 completely fill the slot. 



(b) If the slot reactance is calculated on the assumption that 

 all of the leakage flux per slot is linked with all of the inductors 

 in that slot, what value of leakage flux per ampere per inch of 

 inductor will give the same slot reactance as calculated by the 

 preceding method? 



43. A 125-cycle alternating-current generator has an armature 

 core with slots that are 1.0 in. wide and 3.5 in. deep. Each slot 

 holds 12 inductors in series which completely fill it. (a) Calculate 

 the leakage reactance per inch of slot on the assumption that the 

 path of the leakage flux across the inductors is parallel to the 

 bottom of the slot, and that the permeability of the iron is great. 



(b) If the 12 inductors fill the slot to a depth of but 2.5 in. 

 calculate the leakage reactance per inch of slot on the same 

 assumptions. 



44. A 60-cycle alternating-current generator has an armature 

 core with slots that are 1.1 in. wide and 2.75 in. deep and 15 in. 

 long. There are 6 inductors in series per slot which fill it to a 

 depth of 2.0 in. (a) Calculate the slot reactance on the assump- 

 tion that the path of the leakage flux between the sides of the 

 slot is parallel to the bottom of the slot, and that the permea- 

 bility of the iron is great. 



(b) If the slot reactance is calculated on the assumption that 

 all of the leakage flux per slot is linked with all of the inductors 

 in that slot, what value of leakage flux per ampere per inch of 

 inductor will give the same slot reactance as calculated by the 

 preceding method? 



45. A 3-phase, 25-cycle altenator is rated to deliver 850 

 kv.-a. at 5000 volts. The slots in the armature core are 1.31 

 in. wide and 3 . 625 in. deep. The gross length of the armature 

 core is 14.5 in. and the effective length, deducting for the ven- 

 tilating ducts and the insulation on the laminations, is 10.75 



