Page 653 - Basic Electrical Engineering

or,

Figure 7.30

Example 7.7 A four-pole 220 V dc series motor has 240 slots in the
armature and each slot has six conductors. The armature winding is wave
−2
connected. The flux per pole is 1.75 × 10 Wb when the motor takes 80 A.
The field resistance is 0.05 Ω and the armature resistance is 0.1 Ω. The iron

and friction losses 440 W. Calculate the speed of the motor. Also calculate
the output horse power.

Solution:

In a series motor the armature winding and the field winding are connected in
series across the supply voltage. Thus, the line current, field current, and the

armature current are the same,

i.e., I = I = I = 80 A
L
a
f

The total member of armature conductors, Z = 240 × 6

= 1440

Armature is wave connected, and hence A = 2

No. of poles = 4