Contents
What is excitation current in alternator?
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. You may also see transformer controlled alternators.
What is a excitation current?
1 : a current that excites or energizes an electrical apparatus (such as the field magnets of a dynamo) 2 : the current taken by the primary of a transformer on no load.
How do you find the field current of a synchronous generator?
- Armature current. The line current can be found from the apparent power: S=√3VLLILIL=400,000√3480IL=481A.
- Generator efficiency. To find the efficiency it is first necessary to find the input power. Using simpliifed generator power flow:
- Prime mover torque. The input power is mechanically given by. Pin=τωs.
Why excitation is required for alternator?
To produce magnetic flux the rotor of synchronous machine needs a dc field current. This field current is supplied and controlled by excitation system. he amount of excitation required to maintain the output voltage constant is a function of the generator load.
Why exciter is used in alternator?
The main purpose of exciter in a generator(alternator) is to provide stationary rotating magnetic field. Which is used to induce the e.m.f in the armature coil. So, DC power is given to exciter and the exciter is nothing but a coil, and the exciter creates a magnetic field.
How do you measure excitation current?
the exciting current measurement is performed by applying an aC (60hz) Voltage (typically at 10kV) across a primary winding of the transformer while simultaneously measuring the current flowing through the same primary winding (while the secondary and ter- tiary winding(s) of the transformer are open-circuited).
How do you calculate field current?
Calculate the field current for the motor using the formula I = V/R where I is the field current. As an example, assume V is 40 volts and R is 500 ohms: I = 40/500 = 0.08 amps.
How is the excitation current in an alternator or generator controlled?
How the excitation current is controlled in Electrical Alternator or Generator : The excitation current is supplied from the device called AVR (Automatic Voltage regulator). It regulates the excitation current thus controls the generator terminal voltage. AVR (Automatic Voltage regulator) is fed with Alternating current (AC).
How is the voltage of an alternator adjusted?
Excitation current or field current generates magnetic flux in the rotor. Thus, by adjusting the excitation current, the magnetic field can be adjusted. And by adjusting the magnetic field the voltage in alternator or generator terminal can be adjusted or regulated.
How is the excitation current in an AVR calculated?
AVR (Automatic Voltage regulator) is sophisticated device that supply excitation current by real time calculation. It takes data input from various source such as terminal voltage, load condition, load demand etc. Now we know that, the excitation current is nothing but the Direct current (DC) supplied to the rotor circuit to generate magnetic flux.
How is an alternating current induced in an exciter machine?
This machine, called exciter machine, has in the stator an excitation (field) winding connected to direct current. Therefore, an alternating current is induced into the rotor winding. The induced alternating current at the terminals of the rotating 3-phase winding must be rectified.