ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 3 
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' How are the armature stampings made and arranged for 
armatures up to 2 feet in diameter? State the usual ar- 
_ - rangement of stampings for machines of larger sizes. 
Describe the armature construction which gives good venti- 
Jation. 
State the various kinds of slots ot the ‘icin favorable shapes 
used in modern alternators. 
What is understood by the space factor of a slot? 
Give the average slot space factor of a 600 KVA. 5,000 volt 
alternator. 
What considerations infiuence the choice of the armature con- 
ductors for large current machines? 
_ What are the principal properties of an insulation material 
which is placed between the coils and the iron core? 
What should be the minimum thickness of micanite tubes 
employed for a working pressure of 6,500 volts? 
What principal quality has press board (press spahn) and 
what thickness of same should be used for a pressure of 
4,500 volts? 
What precautions are necessary in arranging the coils which 
are in close proximity to the surrounding iron parts of a 
high tension machine ? 
Show by a sketch the arrangement of the armature conduc- 
tors in a single slot of a high tension alternator; each slot 
is to take 6 wires in radial direction and 3 in width. 
In what cases are cast steel poles advantageously applied ? 
Where and why are laminated poles used? 
~What is the usual thickness of the sheet iron employed in 
laminated poles? 
fy iow are the laminations insulated ee each other ? 
-. State the average: proportion of the effective iron section to 
the total volume of a pole. 
