The Speed Of Rotation On Electric Machines
Synchronous generators are by definition synchronous, meaning that the electrical frequency produced is locked in or synchronous with the mechanical rate of rotation or the generator.
The rate or rotation of the magnetic field
nsyn = ns = ( 120 * fc ) / p
fc → electrical frequency, in Hz
nsyn → ns → synchronous speed, rpm
p → H of poles
if the speed of rotor n, for synchronous machine
nsyn = ns = nm
The Internal Generated Voltage
The magnitude of the voltage induced in a give stator phase
Ea = 2 * ? * Nc * ⲫ * f
Ea = K * ⲫ * ⍹
if ⍹ is expressed in electrical radians per second
K = Nc /2
if ⍹ is expressed in mechanical radians per second
K = Nc * p /2
The Equivalent circuit of a synchronous generator
Ea is the internet generates voltage
Vⲫ is the terminal voltage of the generator
There are a number of factors that cause the difference between Ea and Vⲫ
- The distortion of the air gap magnetic field by the current flowing in the stator, called armature reaction – AR
- The self inductance of the armature coils
- The resistance of the armature coils
- The effect of salient pole rotor shapes
Vⲫ = Ea – jXs*Ia – Ra*Ia
Ra -> winding resistance
Xs -> synchronous reactance
Xs = XAR + XAl
XAR → inductance due to AR
XAl →self inductance
The Speed Of Rotation On Electric Machines
there phase can be either Y – Δ
Y → VTLL = 3 *Vⲫ
Δ → VTLL = Vⲫ
SYNCHRONOUS GENERATORS ON ELECTRİC MACHİNES
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