Contents
- 1 What is field excitation?
- 2 What is the meaning of excitation in electrical?
- 3 Why is excitation always DC?
- 4 Why is excitation DC?
- 5 What are the characteristics of an excitation system?
- 6 What is excitation failure?
- 7 How is a field breaker used in an excitation system?
- 8 Why is excitation important in a power plant?
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 meaning of excitation in electrical?
From International Dictionary of Marine Aids to Navigation. 6-4-060. The production of a magnetic field that is used to generate induced current or to provide motive power. The field may be produced by a permanent magnet or by a powered electromagnet.
What is the purpose of excitation?
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 relay?
This relay will operate if the excitation current comes below its predetermined value. If the relay is to operate for complete loss of field along, it must have a setting lies well below the minimum excitation current value which can be 8% of the rated full load current.
Why is excitation always DC?
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 is excitation DC?
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 excitation system work?
The excitation system creates the electromagnetic field in the rotor. The stator has the armature winding that has the electrical energy induced. The stronger the magnetic field created, the stronger the electrical power produced. The strength of the magnetic field is adjusted by controlling the current to the rotor.
How does excitation work?
What are the characteristics of an excitation system?
The dynamic characteristic of the excitation control system refers to the transient process when, in response to an external disturbance (such as a sudden change in the reactive load) or a change in the setting value, the system transits from a stable state to another state at this moment.
What is excitation failure?
Loss Of excitation (LOE) is a very common fault in synchronous machine operating and can be caused by short circuit of the field winding, unexpected field breaker open or LOE relay mal-operation. According to the statistic in China, the generator failure due to LOE accounts for 69.5% of all generator failures [1].
What is a field relay?
The Field Relay provides On/Off control and network connectivity in order to conserve energy and effectively manage the lighting system. The Field Relay uses advanced switching technology specifically designed to handle the large inrush currents and inductive loads found in lighting applications.
What is the definition of an excitation system?
Excitation System. Definition: The system which is used for providing the necessary field current to the rotor winding of the synchronous machine, such type of system is called an excitation system.
How is a field breaker used in an excitation system?
When the field breaker is open, the field discharge resistor is connected across the field winding so as to dissipate the stored energy in the field winding which is highly inductive. The main and the pilot exciters can be driven either by the main shaft or separately driven by the motor.
Why is excitation important in a power plant?
Excitation is an important part of the power plant Electric Generator because it produces the magnetic field required for power generation. This article explains the working of exciters and the types of exciters used.
When do you need more excitation in a machine?
The amount of excitation required depends on the load current, load power factor and speed of the machine. The more excitation is needed in the system when the load current is large, the speed is less, and the power factor of the system becomes lagging.