18 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
in the field winding is about 1,100 amps. per sq. inch, 
for an excitation of 4,300 amperes turns per pole. There- 
fore, with sufficient exactness, the sectional copper area 
of one side of a coil is equal to aa = 3.9 square inches 
and, providing that the space factor is about 0.4, the 
necessary winding space for one side of a coil will be 
3.9 : 
O47) sq. inches. 
If we assume a coil depth of 1.75 inches, the pole core 
height is equal to re = 5.6 inches, consequently for 
convenience we fix it as 5.75 inches (see Fig. 97) with 
a pole shoe height of 1.25 inches. 
469. Dimensions of Magnetic Circuit.—The prin- 
cipal dimensions of the iron body are as follows 
(see Fiz. 98): 
External diameter of the armature...... 80 inches. 
Bore of the armature ........0.y....4. BS us 
Slot width..<. fishin sa Gace hea ee 0.75‘ 
SlOt REN. A ONG wae doe eae ee ee 2.10“ 
Total length of the armature, including 2 
Bir aductes. ... is AL el eee $3 49% 
Length of pole core.............. PR Bee ats AZ ia** 
External diameter of magnet wheel......62.6 “ 
BGR? QkOr hak sa. Ek Ble ahs ae ea eS Be Bing FS 
Pole shoe height...... Fey SONS wae 1.25 * 
Total pole height...... Selby ab eae biel Ge hie ty 
Pole core width ......... bf Mia lad ka 4.75 “ 
Wheel tim-writh.:....0 5 Uo ascise eee twee 1) aed 
Wheel fia Beeb ......c:ss0"aen sa eerie ER 
470. Leakage Factor.—It is necessary to see if the various 
assumptions are sufficiently exact, and the first thing to, do 
is to calculate the leakage factor. 
