How does alternator excitation work?
This method of excitation consists of a smaller direct-current (DC) generator fixed on the same shaft with the alternator. The DC generator generates a small amount of electricity just enough to excite the field coils of the connected alternator to generate electricity.
Why a field current excitation is necessary for the alternator operation?
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.
How is field excitation achieved in a generator?
The rotor or the field coils in a generator produce the magnetic flux that is essential to the production of the electric power. The rotor is a rotating electromagnet that requires a DC ( Direct Current) electric power source to excite the magnetic field. This power comes from an exciter.
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 excitation voltage?
An excitation voltage or current is the amount of electric energy ( D.C ) feed into the field winding of an alternator rotor to produce magnetic flux / field. The output voltage of an alternator depends upon the magnetic field and so the excitation voltage.
What are excitation methods?
Excitation systems can be defined as the system that provides field current to the rotor winding of a generator. Well-designed excitation systems provide reliability of operation, stability and fast transient response. The four common excitation methods include: Shunt or Self Excited.
What are the requirements of excitation system?
The main requirement of an excitation system is reliability under all conditions of service, a simplicity of control, ease of maintenance, stability and fast transient response. The amount of excitation required depends on the load current, load power factor and speed of the machine.
What are the types of excitation system?
Three main types can be distinguished:
- DC excitation system,
- AC excitation system,
- Static excitation system.
- Block Schematic of Excitation Control:
- STATIC EXCITATION SYSTEM.
- BRUSHLESS EXCITATION SCHEME.
- AC EXCITATION SYSTEM.
- DC EXCITATION SYSTEM.
What is excitation current and what are its components?
A transformer exciting current is the current or amperes required to energize the core. The excitation current is made up of two components. The real component in the form of losses that are commonly referred to as no-load losses. The second form is reactive power measured in KVAR.
What is the main aim of doing open and short test for transformer?
The open circuit and short circuit test are performed for determining the parameter of the transformer like their efficiency, voltage regulation, circuit constant etc. These tests are performed without the actual loading and because of this reason the very less power is required for the test.
What is field current?
: the current supplied to the field windings of a generator or motor to establish the magnetic field for its operation.
What is load current?
The Load Current can be defined as 1) Full load current: the maximum current that an electrical machine can operate; 2) Rated Current: the current rated on the nameplate of an electrical machine; 3) Nominal Current: is generally mentioned in the specification documents that is normally the same value as the rated one; …
How is load current measured?
Electric current is measured in amperes, but actually in most electronics work, you’ll measure current in milliamps, or mA. To measure current, you must connect the two leads of the ammeter in the circuit so that the current flows through the ammeter.
What is the function of the load?
Load affects the performance of circuits with respect to output voltages or currents, such as in sensors, voltage sources, and amplifiers. Mains power outlets provide an easy example: they supply power at constant voltage, with electrical appliances connected to the power circuit collectively making up the load.
What is maximum load current?
The maximum load current is the smallest amount of current in amps that must be drawn from a particular output for that output to function.
When Zener current is maximum load current is?
It’s knee current, breakdown current, or minimum current is 0.25 mA. The maximum current is calculated by dividing the power rating by the Zener voltage: I=P/V = 3W/12V = 0.25A.
What is the formula of full load current?
Full load current I = P / (V x Cos pi) Amps KW = output power in Watts……. All are given at the motor’s nameplate details.
When load current is zero the zener current will be?
Answer: When load current is zero, the zener current will be 0.
What is the minimum Zener current?
2 Answers. The minimum current for reasonable regulation is Izk, but this parameter is not always shown in the datasheet. It is the current in the zener at the corner where it is just starting to break over.
What happens to zener diode after the breakdown voltage is exceeded?
This is important because once the voltage across a Zener diode exceeds its breakdown voltage, the voltage across the Zener remains constant. This means that even if the current going through the diode continues to increase, the voltage remains the same.