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Electrical Applications 2 by David W. Tyler

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DC machines 105
Useful output (generator)
1 Tota I
input (motor)
i/Io
Field loss - l//
f
(shunt machine)
\ Power from armature
circuit (generator)
Power to armature
circuit (motor)
f Generator
εΐοϊ
Armature loss Brushresistance
7
a
2
(total
resistance
of the armature
circuit)
Losses due to Friction Windage Iron
Motor
f
Total
input
(generator)
»Useful output
(motor)
Figure 6.49
Typically this will lie between 0.6 and 0.85 according to the rating
of the machine.
PROBLEMS FOR
SECTION 6
11 What is the function of a commutator in a d.c. machine?
12 What is the basic difference between a lap an