About the armature reaction on DC machines

1. Field MMF (Fm)
A
d- axis
O
Flux due to field
current alone
GNA
MNA (At no load)
Main Field Flux produced by field m.m.f at no load
d- axis

2. N
S
O
d- axis
Armature MMF
(Fa)
q - axis
GNA
BFlux due to
Armature
current alone
d- axis
Armature Field Flux produced by
Armature m.m.f with field unexcited
q - axis
GNA

3. d - axis
Fa
m
A
d-
axis
F
GNA
MNA (At on load )
O
FR
θ
Resultant of Main Field Flux and Armature Field Flux

4. Generator
Direction
x x x x x x
N S
Polar Axis Interpolar Axis
GNA
MNA
Polar AxisMotor
Direction
Bm Fa
Ba
ϕ
Flux distribution and Flux waveforms due to Field and
Armature currents
ϕm
ϕa

5. Peaky
wave
Mmf
& B
Resultant Flux waveform
ϕ

6. Demagnetizing and Cross-magnetizing Conductors:

8. Calculation of Cross-magnetizing Amp-Turns