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An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. In normal motor operation, the stator flux rotation is faster than the rotor rotation. This causes the stator flux to induce rotor currents, which create a rotor flux with magnetic polarity opposite to stator.
What are the limitations of induction generator?
The major limitation of an Induction Generator is that it requires reactive volt-amperes from the auxiliary equipment. An Induction Generator cannot generate reactive volt-amperes. It requires reactive volt-amperes from the supply mains for the excitation process.
What is the difference between induction generator and synchronous generator?
Difference between synchronous generator and induction generator. In a synchronous generator, the waveform of generated voltage is synchronized with (directly corresponds to) the rotor speed. Induction generator takes reactive power from the power system for field excitation.
Which of the following is NOT advantage of induction motor?
Induction Motor Disadvantages: 3 phase induction motors have poor starting torque and high have in rush currents. Therefore these motors are not widely used for applications which require high starting torques like traction systems. Squirrel cage induction motor have poor starting torque.
How do you determine the speed of a generator?
If you know the AC frequency then RPM = 60*( frequency/(number of poles/2)). Most generators have two poles, so if your generator produces 60 Hz AC, then it must turn at 3600 RPM. If 50 Hz, then 3000 RPM.
Is induction generator is self excited machine?
Induction generator is self excited machine. Induction generator can only work at leading reactive power. Explanation: Because it can not supply any lagging power factor.
Do wind turbines generate AC or DC?
The generator in a wind turbine produces alternating current (AC) electricity. Some turbines drive an AC/AC converter—which converts the AC to direct current (DC) with a rectifier and then back to AC with an inverter—in order to match the frequency and phase of the grid.
How voltage build up of an isolated induction generator takes place?
A small EMF is induced in the stator at a frequency proportional to the rotor speed. The voltage appearing across the three phase capacitor bank gives rise to a leading current drawn by the capacitor bank. As a result, the voltage is increased.
Which is better synchronous or asynchronous generator?
Synchronous generators (large ones at least) are more efficient than asynchronous generators. Synchronous generators can more easily accommodate load power factor variations. Synchronous generators can be started by supplying the rotor field excitation from a battery.
Which of the following is the advantage of induction generator?
There are some advantages of induction generator which are given below. The induction generator is smaller in size per kilowatt output power. It needs less auxiliary equipment. Parallel operation is possible without hunting.
What are the advantages and disadvantages of an asynchronous generator?
The main disadvantage: large-capacity induction generator must operate in parallel with the synchronous generator or grid run by the synchronous generator or grid required to provide their own excitation reactive, so asynchronous generator is reactive power load, although in principle said capacitor isolated Nov 1, 2013
Under what condition can an induction machine be operated as a generator?
The Induction Motor becomes a generator when it is connected to an electrical power system and then driven above its synchronous speed by some prime mover.
How does a Dfig generator work?
The principle of the DFIG is that stator windings are connected to the grid and rotor winding are connected to the converter via slip rings and back-to-back voltage source converter that controls both the rotor and the grid currents. Thus rotor frequency can freely differ from the grid frequency (50 or 60 Hz).
Can I use an AC motor for a wind turbine?
Simply take any old AC motor, add magnets to the rotor, put it in the wind and you have power. A fan motor, no matter if its a box fan, table fan or a huge gigantic barn fan, will work perfectly well for this. Take any AC motor with fan blades on it.
Why an induction generator is not a self-excited generator?
If the torque becomes greater than the pushover torque, the generator will over speed. The induction generator is not a self-excited generator. Since the speed of the induction generator is different from the synchronous speed, it is known as an Asynchronous generator.
How is induction generator self excited?
Self-excited induction generator A capacitor bank can be connected across the stator terminals to supply reactive power to the machine as well as to the load. When the rotor is rotated at an enough speed, a small voltage is generated across the stator terminals due to residual magnetism.
How can 3 phase induction motor be used as a generator?
How to Use a Three Phase Induction Motor as a Generator
- Note the three-phase induction motor’s nameplate information including voltage, horsepower rating, and rpm (revolutions per minute).
- Connect the motor’s L1, L2, and L3 (and the ground terminal leads) to the three 208-volt, three-phase power leads and ground, just as if it were a motor application.
Can a motor be used as a generator?
You can generate an alternating current with a fractional horsepower motor. For convenience, the motor should be mounted on a board, as shown, with 4 mm sockets allowing connections to the rotor and stator windings. Connect the field (stator) windings to the low-voltage supply.
Why the torque is negative during generator mode?
Similarly in a generator, an external mechanical system is driving the rotation, therefore the mechanical torque from the driving system will be in the direction of motion (positive, counter-clockwise) and in steady state the electrical machine will produce an equal and opposite torque (negative, clockwise).
What is the use of generator?
Electric generator, also called dynamo, any machine that converts mechanical energy to electricity for transmission and distribution over power lines to domestic, commercial, and industrial customers. Generators also produce the electrical power required for automobiles, aircraft, ships, and trains.
What are the applications of induction generators?
Induction generators are useful in applications such as mini hydro power plants, wind turbines, or in reducing high-pressure gas streams to lower pressure, because they can recover energy with relatively simple controls. An induction generator usually draws its excitation power from an electrical grid.
Why capacitor is used in induction generator?
The function of the capacitor bank is to provide the lagging reactive power to the induction generator as well as load. There is generation of small terminal voltage oa (as in figure given below) across the stator terminal due the residual magnetism when the rotor of the induction machine runs at the required speed.
