Effect Of Load and Field Current Changes in
Synchronous Motor
Presentation -01
Name
:Mir Rafsan
Student ID :1711013
Synchronous motor are Synchronous
machines used to convert electrical
power to mechanical power
Objective:
For Load and Field Current Changes We
will see how Internally Generated Voltage
(EA ) power factor (Pf) and Armature
current (IA ) changes
Vϕ
Phasor Diagram
θ
δ
J IA X s
IA
EA
For lagging condition Phasor Diagram
Effect Of Load Changes in Synchronous Motor:
We know Internally Generated Voltage,
E A =K ϕ ω ω and ϕ Constant So E A =Constant
where ω =synchronous speed of Motor and ϕ =Flux
Leading power factor
Unity Power factor
Lagging Power Factor
Vϕ
IA2
IA1
Vϕ
θ2
θ1
θ3
θ4
IA4
IA3
Vϕ
IA5
δ5
δ3
δ4
EA5
δ1
EA1
δ2
EA3
EA2
Load δ IA θ
EA4
Cosθ
Load δ IA θ Cosθ
Locus
point
Effect Of load changes in Leading ,Unity
and Lagging Power factor
Effect on Field Current Changes:
Real Power Supply ∝ Load on synchronous Motor (As Load=Constant So
P=Constant)
3 Vϕ E Sin δ
p=
Xs
EA Sin∝=K
E=K ϕ ω ω=constant
P=√3 VICos θ
ϕ ∝ If
E A ∝ If
IA Cos θ=k
P=Real Power
ϕ = Flux
IA Cos θ
IA Cos θ
θ1 θ2
θ4
IA2
E A Sinδ
E A2
IA5
Vϕ
E A3
E A1
E A Sinδ
Vϕ
E A Sinδ
E A5
E A4
Lagging
If
IA3
θ3
Vϕ
IA1
IA Cos θ
IA4
EA I A θ Cosθ
Unity PF
Leading PF
PF
If
EA I A θ
Cos θ
Figure:Effect on Field Current Changes
Effect of Field
Current in
Leading ,Unity
and Lagging
Power factor
V curve
Synchronous
Motor
Thank You