TERM 1
Stator
DEFINITION 1
Has a laminated design to reduce eddy current lossesSilicon
steel to reduce losses due to hysteresisHas slots distributed
around the circumference3 phase windings embedded in
slots which are shifted by 120 degsSerial connection of
windings in slots
TERM 2
Rotor
DEFINITION 2
Not a laminated designCylindrical with a uniform air
gapSalient poles with a non-uniform air gapPermanent
magnetExcited by DC current2 poles of DC magnetic field
TERM 3
Air gap
DEFINITION 3
Between the stator and rotorThe larger the air gap the better
the quality of the machineAs poles and diameter decrease,
the length and air gap increase
TERM 4
Principles of Ops
DEFINITION 4
1) Exciter provides DC current to the rotor win dings which creates static
magnetic field in rotor windings2) Rotor is ro tated mechanically by prime mover
with synchronous speed (nsyn). As the roto r rotates the magnetic field also
rotates.3) Rotating magnetic field of rotor indu ces emf in the stator windings
which are 3 phase windings4) If we have a balanced load connected to stator
terminal current flows through the windings and this current is 3 phase5) Current
in the stator windings produces the armature reaction magnetic field (ARMF)
which according to Lenz law tries to slow do wn the rotor by creating a torque in
the rotor (more power supplied). Therefore m ore mechanical power is needed to
counter this torque. As power demand incre ases, current increases which means
ARMF increases.6) For a balanced load, if n's yn is the speed of the ARMF, then we
have nsyn = n'syn = 120f/p. Thus the ARM field rotates in sync with the rotor for
balanced load.7) SG is a (V,P) source. We ca n control the peak voltage and peak
power of SG, but cannot control the phase.
TERM 5
Full Pitch
DEFINITION 5
(phi)bottom - (phi)top = pislots 1 2 3 4 5 6 7 8 9 10 11 12top
A A A A B B B B C C C Cbot B B C C C C A A A A B B
