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What is excitation and why is it needed for start up in an AC generator?
An alternator is just another name for a synchronous generator. Excitation is needed to create a magnetic field in the rotor. When to rotor is spun with excitation the magnetic field will cut through the stator field and produce an AC voltage in the stator field. In terms of an alternator with built in rectifier the stators AC voltage in the rectified to DC. The strength of excitation will determine the alternators output voltage. The AVR Automatic Voltage Regulator built into almost every alternator controls field current to maintain a constant output voltage.
Where does the voltage that is necessary for field excitation on the rotor originates from?
The excitation current is provided by a small self-excited pilot generator, attached to the same shaft as the alternator's rotor.
If the excitation of generator changes what happens to the terminal voltage?
By Decreasing the excitation voltage the terminal voltage will decrease and similarly by increasing the excitation voltages the terminal voltage will also increases.
What is exitation voltage?
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What is characteristics of LVDT?
1.Null Voltage 2.Resolution 3.Linearity 4.Sensitivity 5.Excitation voltage and excitation frequency 6.Dynamic response
How do you calculate the excitation voltage and current of an alternator?
formals to calculate exciation voltage of alternator
Why The Excitation current is non-sinusoidal when applied voltage is sinusoidal?
excitation voltage is sinusoidal because it is taken from the terminal of alternator but excitation current is non-sinusoidal because it always dc.
What is excitation and why is it needed for start up in an AC generator?
An alternator is just another name for a synchronous generator. Excitation is needed to create a magnetic field in the rotor. When to rotor is spun with excitation the magnetic field will cut through the stator field and produce an AC voltage in the stator field. In terms of an alternator with built in rectifier the stators AC voltage in the rectified to DC. The strength of excitation will determine the alternators output voltage. The AVR Automatic Voltage Regulator built into almost every alternator controls field current to maintain a constant output voltage.
Where does the voltage that is necessary for field excitation on the rotor originates from?
The excitation current is provided by a small self-excited pilot generator, attached to the same shaft as the alternator's rotor.
In what situation is the generated voltage at its maximum?
On auto alternator 1000 rpm
What is meant by regulation or an alternator?
Regulation of an alternator is varying or adjusting the d.c. current flow (excitation current) in the revolving field coil to control the output voltage. When an alternator is subject to varying load conditions, and therefore changing load resistance at the output, the output voltage will vary in response. When output voltage is reduced in response to increased load (reduced output resistance), the "voltage regulator" will respond by increasing the excitation current to increase the voltage output. If load is reduced, the generator will momentarily become over-excited and the ouput voltage will increase. The voltage regulator responds by decreasing excitation current, returning the generator output voltage to its nominal level.
How is the output voltage of an alternator regulated?
The output voltage of an alternator is regulated primarily through a device called a voltage regulator. This regulator monitors the output voltage and adjusts the excitation current supplied to the rotor windings, ensuring that the output voltage remains within a specified range. By increasing or decreasing the excitation current, the regulator can control the magnetic field strength, thus stabilizing the alternator's voltage output under varying load conditions. Additionally, some systems use feedback mechanisms to maintain consistent voltage levels despite fluctuations in demand.
If the excitation of generator changes what happens to the terminal voltage?
By Decreasing the excitation voltage the terminal voltage will decrease and similarly by increasing the excitation voltages the terminal voltage will also increases.
Generator excitation voltage?
the voltage which is given for creating magnetic field in a generator is known as excitation voltage.
Why the rotor of an alternator at rated power dissipates more heat at a low power factor load?
In an alternator, the load current is supplied by the stator and the excitation is applied to the rotor. When the power factor is low (lagging), more excitation is required to maintain rated output voltage at rated current. More excitation is also required to maintain rated output voltage with increased output current. Increased excitation current means increased rotor losses that must be dissipated as heat. (akash)
How do you derive alternating current from car alternator?
The car's alternator is a three phase generating system. Inside the alternator is a three phase full wave diode bridge that changes the AC generated voltage to a DC voltage.
Why does the no-load characteristic differ for increasing and decreasing excitation current?
The no-load characteristic of a generator differs for increasing and decreasing excitation current due to magnetic hysteresis, residual magnetism, and core saturation effects. When the excitation current increases, the magnetic domains in the iron core gradually align with the applied magnetic field, resulting in a higher generated electromotive force (EMF). However, as the excitation current decreases, these magnetic domains do not immediately return to their original unaligned state. This lag in realignment causes the generated voltage to remain higher during the decreasing phase of excitation than during the increasing phase at the same level of excitation current. This phenomenon is known as magnetic hysteresis. Even when the excitation current is zero, the magnetic core retains some level of magnetisation, known as residual magnetism. This residual magnetic field means that when the excitation current starts increasing again, it takes additional current to overcome this residual alignment before the generated voltage rises significantly. As a result, the voltage is initially lower when increasing the excitation current from zero. Conversely, during the decreasing phase, the residual magnetism keeps the voltage higher than it would be if the core were fully demagnetised, further contributing to the difference between the increasing and decreasing curves. As the excitation current increases, the magnetic core of the generator approaches saturation. Near saturation, any further increase in excitation current results in only a small increase in generated voltage because the core's magnetic domains are almost fully aligned. When the excitation current decreases from this saturated state, the magnetic domains gradually return to a less aligned state. This gradual realignment causes the generated voltage to decrease differently than it increased, contributing to the asymmetry between the increasing and decreasing excitation phases.
