Why does DC excitation is used rather than AC excitation?

In the alternator, as the rotor conductor changes its position as the rotor rotating so constant flux is to be produced in the rotor winding and it is possible only when the DC supply is given to the rotor winding. As we need constant flux that is why DC is used instead of AC for excitation of Synchronous Alternator.

Why do we get an output voltage at the alternator terminals without the DC excitation?

This is caused by residual magnetisation within the rotor of the machine. Even when no DC excitation is absent there is enough magnetism to generate voltage on the alternators output terminals .

What is AC excitation?

The excitation system on a AC alternator refers to the way the alternators voltage is initially built when rotated and controlled while in use. The excitation system is responsible for supplying the field current to the main rotor.

What is DC excitation system?

What is an Excitation System? Definition: The system which provides DC to the synchronous machine field winding to perform protective & control functions of the power system. This system consists of exciter, PSS (Power System Stabilizer), AVR (Automatic Voltage Regulator), processing unit, and measuring elements.

Why excitation is required for alternator?

The excitation system is responsible for supplying the field current to the main rotor. The requirements of an excitation system include reliability under all conditions of service, a simplicity of control, ease of maintenance, stability and fast transient response.

What changes AC to DC in the alternator?

Rectifier. The rectifier is used to convert current from alternating current (AC) to direct current (DC) during the charging process.

What is the function of the AC excitation winding?

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 the function of exciter?

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.

What is ac excitation?

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 is the excitation current in a transformer?

Transformer Excitation Current Vectors Typical core loss current (I c) is around 1\% of the full load current. Typically magnetizing current (I m) can vary from about 0.25\% to about 5\% of full load current (0.05 pu) and can be as high as 10\% in some special transformers.

What is the difference between core loss and excitation current?

Note that core loss current (I c) is largely in phase with the supply voltage (V oc ) while the magnetization current (I m) lags voltage by 90 0 . The total excitation current I ex can be calculated to be: Typical core loss current (I c) is around 1\% of the full load current.

Can alternating current be converted to direct current?

However, in some electronic appliances, the alternating current is first converted into direct current. The alternating current not only reverses its direction but also changes its magnitude. In simple words, the magnitude of the alternating current or voltage changes with respect to time.

How long does it take to convert from AC to DC?

Many household items are designed to operate on AC, however, some items such as battery chargers, electric trains, and other toys are designed to operate on DC. Diodes are used as rectifiers, to convert AC to DC. Time: 20-30 minutes Materials and Supplies: