How Many Types Of Exciter Are There?

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Advantages of Static Excitation System

Since excitation energy is directly taken from generator output terminals therefore excitation voltage is directly proportional to the Generator speed. This improves the overall system performance.

Do all generators have exciters?

Many variety of exciters are available, but the most popular today is brushless exciter. In a brushless exciter, excitation power is generated by a small alternator whose armature is driven by the main generator shaft. … The DC output of rectifier is fed to the rotating field winding of the main generator.

What are generator exciters?

A Exciter. The exciter supplies direct current to the field winding of the generator, at whatever voltage is required to overcome the resistance of the winding. … Over the years, many types of exciters have been used, but the type most commonly used was the comutator-type dc generator.

Why DC is used for excitation?

Why only D.C is used for Excitation in Alternators? Excitation voltage or current is supplied to the field windings of a rotor to produce a static magnetic field. If we use alternating current instead of direct current; we will get a fluctuating magnetic field.

How does a static exciter work?

Static Exciter

A number of high power thyristors rectify the AC current to produce a DC current which feeds to the rotor through slip rings. This eliminates the operation and maintenance problems associated with having another rotating machine.

Why do generators need excitation?

Generators turn mechanical energy into electrical energy by moving electrical conductors in a magnetic field. Excitation creates the electromagnetic field to make this mechanical to electrical conversion occur.

What is self excitation?

a kind of excitation of generators where the magnetic field of the main poles is excited by a current supplied to the windings of the main poles from the armature (rotor) winding. … Self-excitation is made use of most often in DC generators.

Why does DC excitation is used rather than AC excitation?

So if we give AC supply the pole created in the rotor winding will be alternating and it not be created any magnetic locking with the stator field. So if we give AC supply, the rotor will stop rotating after removing the prime mover. This was the reason Why DC is used not AC for excitation of Synchronous Motor.

Does alternator need excitation?

Without the excitation system the AC alternator would have no way of building its voltage as it starts to rotate, nor would not be able to regulate its voltage to the pre-set nominal level while running at its rated speed. So, without an excitation system, an AC alternator would be useless for its purpose.

What is AVR?

An automatic voltage regulator (AVR) is an electronic device that maintains a constant voltage level to electrical equipment on the same load. … Without an automatic voltage regulator, voltage can sag, spike or surge and damage electrical devices.

What is excitation AC excitation and DC excitation?

The DC excitation system has two exciters – the main exciter and a pilot exciter. The exciter output is adjusted by an automatic voltage regulator (AVR) for controlling the output terminal voltage of the alternator. The current transformer input to the AVR ensures limiting of the alternator current during a fault.

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What are the elements of excitation system?

The main components of excitation system are voltage regulators, excitation system stabilizers, power system stabilizers, voltage sensing and load compensator, under-excitation limiters, over-excitation limiters, and volts-per-hertz limiters.

What happens when exciter fails?

Again when loss of field occurs due to failure of exciter but not due to problem in the field circuit (field circuit remains intact) there will be an induced current at slip frequency in the field circuit. This situation makes the relay to pick up and drop off as per slip frequency of the induced current in the field.

What does excitation mean?

: excitement especially : the disturbed or altered condition resulting from stimulation of an individual, organ, tissue, or cell.

What is separate excitation?

: having the field magnets excited by a current from a separate source —used of a machine.

What is excitation in psychology?

n. the electrical activity elicited in a neuron or muscle cell in response to an external stimulus, specifically the propagation of an action potential.

How do you control the excitation of a generator?

All methods use an Automatic Voltage Regulator (AVR) to supply DC output to the exciter stator. The exciter rotor AC output is rectified to a DC input for the main generator rotor.



Excitation Systems

  1. Shunt or Self Excited.
  2. Excitation Boost System (EBS)
  3. Permanent Magnet Generator (PMG)
  4. Auxiliary Winding (AUX).

What is PMG excitation?

In PMG excitation systems, the AVR power supply voltage is generated by a permanent magnet generator (PMG) that is mounted on the shaft extension at the non-drive end of the alternator. The PMG delivers a constant voltage, regardless of the main alternator winding.

What is the purpose of excitation system?

The basic function of an excitation system is to provide a continuous (DC) current to the field winding of a synchronous machine. This is achieved through the use of closed-loop control (or feedback control).

What is field excitation?

The process of generating a magnetic field by means of an electric current is called excitation. Field coils yield the most flexible form of magnetic flux regulation and de-regulation, but at the expense of a flow of electric current.

What does flashing the field mean?

Flashing the field is simply a process to pass some DC current through the field windings. When dis. A self excited DC generator requires some residual magnetism in the field poles to begin generating a voltage. However if it has not been used for a long time this residual magnetism sometimes disappears.

Why AVR is used in generator?

An automatic voltage regulator (AVR) is a device used in generators with the purpose of automatically regulating voltage, which means that it will turn fluctuating voltage levels into constant voltage levels.

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