Electrical and Instrumentation Engineering: Unit III: AC Rotating Machines
Equation of Induced EMF in Alternator
Derivation of Equation of induced emf
EQUATION OF INDUCED EMF
Let,
Zph
= number of conductors or coils sides in series/phase
Zph
= 2Tph, where Tp is the number of coils or turns per
phase
P
= number of poles
f
= frequency of induced emf in Hz
φ
= flux/pole in webers
Kc
or Kp = pitch factor or coil span factor = cos (α/2)
Kf
= form factor = 1.11 (If e.m.f is assumed sinusoidal)
N
= rotor speed in r.p.m.
For
one revolution of the rotor, each stator conductor is cut by a flux of φP
webers
dφ
= φР
dt
= 60/N Second.
Average
emf induced per conductor = dφ/dt = φР / (60/N) = φΡΝ / 60
We
know that f = PN / 120 (or) N = 120f / P
Substituting
this value of N, we get average emf per conductor as
If
there are Zph conductors in series/phase, then
Average
e.m.f / Phase = 2fφ Zph volts = 4fφ Tph volts
RMS
value of e.m.f / Phase = 1.11 × 4fφ Tph = 4.44fφ Tph
Volts.
The
above equation is true only if the winding concentrated in one slot. But
practically it is not true, as the winding for each phase under each pole is
distributed and for such cases kp and kd must be
considered.
Actually
available voltage/phase = 4.44 kp kd fφ Tph
Volts
Kp
kd = kw = winding factor.
If
the alternator is star connected, then the line voltage is √3 times the phase
voltage.
Electrical and Instrumentation Engineering: Unit III: AC Rotating Machines : Tag: : - Equation of Induced EMF in Alternator
Electrical and Instrumentation Engineering: Unit III: AC Rotating Machines
Under Subject
Electrical and Instrumentation Engineering
BE3254 - 2nd Semester - ECE Dept - 2021 Regulation | 2nd Semester ECE Dept 2021 Regulation
Related Subjects
Professional English II
HS3251 2nd Semester 2021 Regulation | 2nd Semester Common to all Dept 2021 Regulation
Statistics and Numerical Methods
MA3251 2nd Semester 2021 Regulation M2 Engineering Mathematics 2 | 2nd Semester Common to all Dept 2021 Regulation
Engineering Graphics
GE3251 eg 2nd semester | 2021 Regulation | 2nd Semester Common to all Dept 2021 Regulation
Physics for Electrical Engineering
PH3202 2nd Semester 2021 Regulation | 2nd Semester EEE Dept 2021 Regulation
Basic Civil and Mechanical Engineering
BE3255 2nd Semester 2021 Regulation | 2nd Semester EEE Dept 2021 Regulation
Electric Circuit Analysis
EE3251 2nd Semester 2021 Regulation | 2nd Semester EEE Dept 2021 Regulation
Physics for Electronics Engineering
PH3254 - Physics II - 2nd Semester - ECE Department - 2021 Regulation | 2nd Semester ECE Dept 2021 Regulation
Electrical and Instrumentation Engineering
BE3254 - 2nd Semester - ECE Dept - 2021 Regulation | 2nd Semester ECE Dept 2021 Regulation
Circuit Analysis
EC3251 - 2nd Semester - ECE Dept - 2021 Regulation | 2nd Semester ECE Dept 2021 Regulation
Materials Science
PH3251 2nd semester Mechanical Dept | 2021 Regulation | 2nd Semester Mechanical Dept 2021 Regulation
Basic Electrical and Electronics Engineering
BE3251 2nd semester Mechanical Dept | 2021 Regulation | 2nd Semester Mechanical Dept 2021 Regulation
Physics for Civil Engineering
PH3201 2021 Regulation | 2nd Semester Civil Dept 2021 Regulation
Basic Electrical, Electronics and Instrumentation Engineering
BE3252 2021 Regulation | 2nd Semester Civil Dept 2021 Regulation
Physics for Information Science
PH3256 2nd Semester CSE Dept | 2021 Regulation | 2nd Semester CSE Dept 2021 Regulation
Basic Electrical and Electronics Engineering
BE3251 2nd Semester CSE Dept 2021 | Regulation | 2nd Semester CSE Dept 2021 Regulation
Programming in C
CS3251 2nd Semester CSE Dept 2021 | Regulation | 2nd Semester CSE Dept 2021 Regulation