ALTERNATING GUNERATORS AND SYNCHRONOUS MOTORS. 23 
For high tension, the triple covering of thicknesses as per 
Table ¥ has been found sufficient. 
TABLE 7.—INSULATION THICKNESSES OF ROUND 
WIRES AS USED FOR HIGH TENSION. 
Double Cotton Covering 
Triple Cotton Covering. and One Braiding 
.012 inch. .027 inch. 
ts ¢. ae Es | 6 Blin 
1020... ** ga. )** 
,0B8:  ** 036 
46. Arrangement of Conductors.—The arrangement of 
wires inside the slots is a matter of importance, and the 
proper arrangement and succession of the turns will add 
much to the safety against breakdown. Fig. 11 shows a 
slot with its high tension winding. The armature coil has 
been formed on a mould, taped over with cloth, 0.008 ineh 
in thickness and placed inside the slots, which are insulated 
from the armature coil by suitable material. 
In modern practice it is required that any defective coil 
may readily be taken out and replaced by a sound coil; 
that a defective coil can be temporarily cut out of cireuit 
Fie. 11.—Stor WIinpInG or ExtrRA HiGgu TENSION ALTERNATOR. 
and bridged over until repairs are possible; that any 
shifting of the coils shall be practically impossible, and 
that the potential difference between any two neighboring 
eoils of different phase shall be reduced to a minimum. 
