1). What is a synchronous generator and how does it operate?
A synchronous generator is a mechanism that converts mechanical energy into electrical energy using electromagnetic induction. It runs at a constant speed (synchronous speed), with the generated voltage frequency synchronized with the rotor’s spinning speed.
2). What is the synchronous speed in a synchronous generator?
Synchronous speed is the rate at which the rotor of a synchronous generator must rotate in order to produce electricity at the desired frequency. The formula is as follows:
Synchronous Speed = (120 x f) /(Number of Poles)
Synchronous speed (rpm) is calculated by multiplying the number of poles (120) by the frequency.
3). What are the key components of a synchronous generator?
The main components are:
Stator: The stator contains the armature windings that provide the output voltage.
Rotor: The rotating component that generates a magnetic field.
Slip rings : Slip Rings transfer power to & from the rotating rotor.
Exciter: Delivers field current to the rotor.
4). What is the definition of excitation in a synchronous generator?
Excitation is the technique of applying direct current (DC) to the rotor windings to generate the required magnetic field. This can be accomplished using a separate exciter (or) self-excitation.
5). Explain the distinction between a synchronous and asynchronous generator.
A synchronous generator generates electrical power at a consistent frequency and speed, whereas an asynchronous generator (induction generator) uses slip and runs at a variable speed that is slightly slower than synchronous.
6). What is the function of an Automatic Voltage Regulator (AVR) in a synchronous generator?
The Automatic Voltage Regulator (AVR) regulates the generator’s output voltage by regulating the excitation current provided to the rotor. This ensures that the output voltage remains steady even under varying load conditions.
7). Why is it necessary to synchronize a synchronous generator before to connecting it to the grid?
Synchronization guarantees that the generator’s voltage, frequency, & phase sequence correspond to those of the grid. If not properly synced, the system may suffer harm or become unstable.
8). What are the most frequent ways for synchronizing a synchronous generator to the grid?
There are two common methods:
- Lamp method (three-lamp method): Observing lamp brightness to accomplish synchronization.
- Synchroscope method: Using a synchroscope to determine the phase difference between generator and grid.
9). What role do damper windings play in synchronous generators?
Damper windings on the rotor aid to control oscillations and offer damping during transient conditions like synchronization or load fluctuations.
10). What are the advantages & disadvantages of employing synchronous generators?
Advantages:
- Constant-speed operation.
- High efficiency for huge power generation and controllable power factor by stimulation.
Disadvantages:
- More sophisticated than induction generators.
- Synchronization with the grid is required prior to hookup.
- Higher costs for smaller applications.
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