14 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
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erate dimensions, and a cast iron frame or carcase of ample 
cross section has the necessary rigidity in itself to bear 
its own and the weight of the armature core, so with- 
standing any possible one-sided magnetic pull, due to an 
eccentric position of the magnet wheel inside the station- 
ary armature. 
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Fie. 7.—Revorvinc ARMATURE TYPE, 60 CycLE, PoLYPHASE. 
ALTERNATOR OF ENGLISH-AMERICAN Design. (See Table 4.) 
TABLE 4.—DIMENSIONS OF REVOLVING ARMATURE TYPE, 60 
CYCLES, POLYPHASE ALTERNATORS. (SKE FIG. 7.) 
KVA.| REM.) VERB sy e | ef e M N oe 
50 | 900 4,100} 70147 | 292” | 12” | 18” | 463” | 233 | 4687 | 187 } 
75 | 720 | 7,660} 82% |362 | 15° | 25 55k || O72 | 5S 25 
120 | 720 |10,600| 914 |40¢ | 17 | 25 654 =| 34 644 | 25 
180 | 515 |13,800|}1002 | 424 | 25 | 35 T1Z | 35 72 35 
250 | 450 | 22,750 | 155 534 | 38 | 40 85% | 46 98 40 
400 | 400 | 41.000 | 162 584 | 50 | 45 | 109 |54 | 113 45 
600 | 327 |62,000}168$ |614 | 46 | 60 | 134 72 | 142 60 
750 | 327 | 82,000 | 190 704 | 66 | 60 | 147 794 | 142 60 
For an overall diameter not exceeding five feet, the cast 
iron frame is preferably cast in one piece and is pro- 
vided with the necessary ventilating holes. 
Armature frames with an overall diameter of above five fect 
are divided in two, four or more parts, according to the 
size, and are usually of box section, as shown in Fig. 8. 
For very large generators, the question of transportation 
