DIRECT-CURRENT DYNAMCGS AND MOTORS. 
84. 
85. 
86. 
87. 
88. 
89. 
90. 
Make'a similar comparison between the two 150 K. W. low- 
speed machines given in the same table. 
From the data given in Table 11, Instruction Book, com- 
plete the following table of approximate average speeds 
of high, medium, and low speed ring dynamos: 
TABLE OF AVERAGE RING ARMATURE SPEEDS. 
Output, in Kilowatts.|| High Speed. Medium Speed.| Low Speed. 
2.5 2 1600 |. 1100 500 
5 1400 1000 400 
10 
50 
100 
150 
250 
500 ae 
1000 
From the figures of Table 12 compile a similar table of. 
average drum armature speeds for .5, 1, 2,5, 10, 25, 50, 
100, and 200 K. W. machines. 
State the limits between which it is customary to choose the 
specific cross-section of the armature conductor. 
What is the specific conductor cross-section usually allowed 
in armatures for ordinary dynamos? 
In what class of machines is it expedient to use the lower 
limit referred to in Question 8%, and in what class of 
machines is the upper limit of specific cross-section em- 
ployed? 
What portion of the total current flows through each arma- 
ture conductor in a bipolar armature? 
