The Magnetic Flux does not move through a Coil or passes through a Coil. Unlike Current, Flux does not move. We say that the Flux is linking the Coil. When the Direction of Flux is perpenducular to the Plane of Coil, we say that the Flux is linking the Coil. When the Direction of Flux is in the Plane of Coil, we say that the Flux is not linking the Coil.
When Maximum Flux is linking the Coil, the rate of change of Flux is Zero, hence Induced EMF is Zero. When Flux linking the Coil is Minimum, the rate of change of Flux is Maximum, hence Induced EMF is Maximum.
When a Pure Inductive Load is connected to the Generator, Current lags Voltage by 90 degree, hence Induced Current is Maximum when Poles are ahead by 90 degree. When a combination of Inductive and Resistive Load is connected, Maximum Current is Induced when Poles are in advance by fi + delta where delta is Load Angle between Induced EMF and Terminal Voltage.
In case of a Pure Resistive Load, Maximum Current is Induced in a Coil when Poles are ahead by delta.
In case of Capacitive and Resistive Load, Maximum Current is Induced when Poles are behind the Coil. In case of a Pure Capacitive Load, Maximum Current is induced when Poles are behind by 90 Degrees.
As per Faraday's Second Law of Electromagnetic Induction, Induced EMF = -Ndfi/dt. Solving we get EMF = N fim omega sin(omega t - 90). Thus the EMF, Voltage and Voltage Drop due to Armature Reaction lags Main Flux, Resultant Flux and Armature Reactance respectively by 90 degrees.
Thus Phasor Diagram of Flux and Voltage is drawn.
As the Load increases, Terminal Voltage decreases due to decrease in Resultant Flux.
As the Load changes from Resistive and Inductive to Resistive, Resultant Flux increases and thus Terminal Voltage increases.
Негізгі бет Phasor Diagram of Flux and Voltage in Synchronous Generator
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