For the heavy power generation, the stator of the synchronous generator design for voltage ratings between 6. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content Definition: The synchronous generator or alternator is an electrical machine that converts the mechanical power from a prime mover into an AC electrical power at a particular voltage and frequency.
Leave a Comment Cancel Reply Your email address will not be published. Thus a 4-pole generator will run idle at rpm if it is attached to a grid with a 50 Hz current. If the generator is producing at its maximum power, it will be running at rpm. It is a very useful mechanical property that the generator will increase or decrease its speed slightly if the torque varies.
This means that there will be less tear and wear on the gearbox, because of lower peak torque. This is one of the most important reasons for using an asynchronous generator rather than a synchronous generator on a wind turbine which is directly connected to the electrical grid.
Automatic pole adjustment of the rotor The clever thing about the cage rotor is that it adapts itself to the number of poles in the stator automatically. The same rotor can therefore be used with a wide variety of pole numbers. Grid connection required On the page about the synchronous generator we showed that it could run as a generator without connection to the public grid.
An asynchronous generator is different, because it requires the stator to be magnetised from the grid before it works. However, an asynchronous generator in a stand alone system can be used if it is provided with capacitors which supply the necessary magnetisation current. It also requires that there be some remanence in the rotor iron, i. Otherwise a battery and power electronics will be needed, or a small diesel generator to start the system.
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What emergency Supplies is suitable for us when power off? How to choose the brand of diesel generator set. It is the oldest of all due to various problem. Now a days it is not conventionally used for large Alternator s.
It consists of AC generator and thyristors. The rectifier bridge directly connected to the Alternator shaft or driven by separate motor. It is further divided in to two types:. There is no rotating part in this excitation system. It is small in size. The prime mover will rotate the rotor. This makes the rotor flux also rotate along with it at the same speed. Such revolving magnetic flux now intersects the armature coils which is fitted around the rotor this will generate an alternating electromagnetic force across the winding.
Since for polar rotor has got two pairs of NS pole when the rotor turns of half revolution the induced EMF takes one complete cycle. So it is clear that frequency of the induced EMF is directly proportional to the number of poles in rotor speed. It can be easily established that frequency of induced EMF rotor speed and number of poles are connected through the following relationship:. It is clear from this relationship that frequency of electricity produced is synchronized with mechanical rotational speed for producing three-phase AC current.
Two more such armature coils are placed at the phase difference of degree in the stator winding. Generally one end of these three coils are star connected and three-phase electricity is drawn from the other ends neutral cable can be drawn from the star connected end.
It is clear from equation that in order to produce 60 Hertz electricity a four pole rotor should run at following speed of and rpm. Centrifugal force on poles of the rotor will be generated through such huge rpm.
So salient polar rotors are generally having 10 to 40 poles which demands lower rpm. Salient and polar rotors are used when the prime mover rotates at relatively lower speed from to rpm. Otherwise, it would be just like a synchronous motor. Starting of the synchronous motor using the DC generator creates a magnetic field.
Alternator and ac generator is equal. It is conducting OC and SC tests on the given three phase alternator and determining the regulation by synchronous impedance method. It may be called a generator, alternator or dynamo. An electric device that produces an electric current that reverses direction many times per second.
Also called a synchronous generator. Nope, you are confused. Click the link. Turn the DC generator inside out and you have an alternator. Electrical generators are also called dynamos.
The "generator" in a modern car is properly called an alternator. The starting of synchronous motor using a DC generator as a load of work generates the magnetic field.
Because if speed was used, the power system frequency would be changed. A synchronous generator spins at synchronous speeds.
Synchronous generators A typical synchronous generator will have a field winding typically on the rotor, or rotating part and a stator winding the stationary part where power is supplied to the power grid. Current is injected into the field winding, turning it into an electromagnet. The more current supplied to the field winding, the stronger the electromagnet becomes, and the more power is required from the prime mover whatever is supplying the power - steam turbine, for example to keep the generator spinning at synchronous speeds.
Because it produces alternating current which is then converted to DC. Synchronous generators.
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