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To improve the power factor
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What is a system that links electricity produced in power stations to deliver it to where it is needed?
Power Systems or Transmission & Distribution
Why use the synchronous generator in power plant?
The electrical power generated must be AC exactly phase synchronized with the AC on the power grid. If it is not synchronized the generators will take power from the grid and try to run as motors and probably severely damage themselves and maybe other parts of the power plant.
When you should use synchronous motor instead of capacitor for power factor correction?
Synchronous motors show some interesting properties, which finds applications in power factor correction. The synchronous motor can be run at lagging, unity or leading power factor. The control is with the field excitation, as described below:When the field excitation voltage is decreased, the motor runs in lagging power factor. The power factor by which the motor lags varies directly with the drop in excitation voltage. This condition is called under-excitation.When the field excitation voltage is made equal to the rated voltage, the motor runs at unity power factor.When the field excitation voltage is increased above the rated voltage, the motor runs at leading power factor. And the power factor by which the motor leads varies directly with the increase in field excitation voltage. This condition is called over-excitation.The most basic property of sycho motor is that it can be use as a CAPACITOR OR INDUCTOR both. Hence in turn it improves the power factor of system.The leading power factor operation of synchronous motor finds application in power factor correction. Normally, all the loads connected to the power supply grid run in lagging power factor, which increases reactive power consumption in the grid, thus contributing to additional losses. In such cases, a synchronous motor with no load is connected to the grid and is run over-excited, so that the leading power factor created by synchronous motor compensates the existing lagging power factor in the grid and the overall power factor is brought close to 1 (unity power factor). If unity power factor is maintained in a grid, reactive power losses diminish to zero, increasing the efficiency of the grid. This operation of synchronous motor in over-excited mode to correct the power factor is sometimes called as Synchronous_condenser.
Why is a synchronous machine not self starting?
A synchronous generator generally requires DC power supplied to the rotor winding to make it into an electromagnet. As the rotor spins, a voltage will be induced in the stator windings (the stationary windings). A synchronous generator needs something to supply this initial DC power to the rotor, so it may be deemed to not be "self starting". "Self starting" may have several different interpretations, though. A "black start" generator could be deemed as being self starting, even though this initial power is (usually) supplied by a set of batteries. Many generators pull this power from the power grid, so if the grid is not energized (black start conditions), these generators cannot start until at least part of the power grid is put back in service with another generator.
What is the role of reactive power in a power system?
To supply the reactive power demand of load and to regulate of output volage at the grid
Why are synchronous generators used in thermal power plants?
For an alternating current (AC) grid, *every* alternator must be exactly in phase with every other. If not, one will attempt to feed power to the other, rather than adding to the power in the system. Synchronous alternators are easily controlled for speed, and therefore, for phase. As well, synchronous alternators can be made with no electrical contacts, so they are very long-lived and reliable. Be aware that *all* power plants connected to a grid use synchronous machines.
Why do power stations use synchronous generators and not induction generators?
This is not entirely true. In small power stations not connected to grids and wind turbines they usually use induction generators instead of synchronous for their capability of producing energy at varying rotor speeds and their price which is lower the synchronous generators. Before I tell you why they use synchronous in big power stations connected to the grid you must know that usually you have more than one power plant connected to the grid. And if you want the power of each power plant to be added to the grid you need the all the alternating currents to be in phase so the frequency must be the same. And as you probably know they are called SYNCHRONOUS generators because the speed of the rotor (the frequency) is the same as the AC supply current. So obviously it will be much easier to control the frequency of a synchronous generator and therefore easier to synchronize with the grid.
What do paper factories use to power their machines?
Mostly Electricity from Grid
Why is speed not normally used to control the armature voltage of a synchronous alternator?
Because if speed was used, the power system frequency would be changed. A synchronous generator spins at synchronous speeds. Synchronous generators 101: A typical synchronous generator will have a field winding (typically on the rotor, or rotating part) and a stator winding (the stationary part where power is supplied to the power grid). Current is injected into the field winding, turning it into an electromagnet. This field current is controlled by the Automatic Voltage Regulator (AVR). The more current supplied to the field winding, the stronger the electromagnet becomes, and the more power is required from the prime mover (whatever is supplying the power - steam turbine, for example) to keep the generator spinning at synchronous speeds.
What is a system that links electricity produced in power stations to deliver it to where it is needed?
Power Systems or Transmission & Distribution
How does national grid make electricity?
The North American national grid does not make the electricity. The grid is a distribution system that transports power throughout the system to homes that are connected to it. The power for the grid is produced elsewhere at generating stations that feed into the grid.
Why use the synchronous generator in power plant?
The electrical power generated must be AC exactly phase synchronized with the AC on the power grid. If it is not synchronized the generators will take power from the grid and try to run as motors and probably severely damage themselves and maybe other parts of the power plant.
When you should use synchronous motor instead of capacitor for power factor correction?
Synchronous motors show some interesting properties, which finds applications in power factor correction. The synchronous motor can be run at lagging, unity or leading power factor. The control is with the field excitation, as described below:When the field excitation voltage is decreased, the motor runs in lagging power factor. The power factor by which the motor lags varies directly with the drop in excitation voltage. This condition is called under-excitation.When the field excitation voltage is made equal to the rated voltage, the motor runs at unity power factor.When the field excitation voltage is increased above the rated voltage, the motor runs at leading power factor. And the power factor by which the motor leads varies directly with the increase in field excitation voltage. This condition is called over-excitation.The most basic property of sycho motor is that it can be use as a CAPACITOR OR INDUCTOR both. Hence in turn it improves the power factor of system.The leading power factor operation of synchronous motor finds application in power factor correction. Normally, all the loads connected to the power supply grid run in lagging power factor, which increases reactive power consumption in the grid, thus contributing to additional losses. In such cases, a synchronous motor with no load is connected to the grid and is run over-excited, so that the leading power factor created by synchronous motor compensates the existing lagging power factor in the grid and the overall power factor is brought close to 1 (unity power factor). If unity power factor is maintained in a grid, reactive power losses diminish to zero, increasing the efficiency of the grid. This operation of synchronous motor in over-excited mode to correct the power factor is sometimes called as Synchronous_condenser.
What countries do have an isolated power grid (islanded power system) and what are the names of these power grids?
Ireland has an isolated power grid, so does Great Britain.
What is difference between feeder and grid?
In an electrical power transmission system: the grid is what the feeder feed into.
What is grid system?
The power grid system is the Electrical utility distribution system which provides power to the consumer (end user.) Beginning at the Power Generation Plant , continuing on thru the transmission lines and to the substation and local distribution network, finally to the individual consumer. Power grids are smaller distinct sections of this system which together make up the entire distribution network.
Why is a synchronous machine not self starting?
A synchronous generator generally requires DC power supplied to the rotor winding to make it into an electromagnet. As the rotor spins, a voltage will be induced in the stator windings (the stationary windings). A synchronous generator needs something to supply this initial DC power to the rotor, so it may be deemed to not be "self starting". "Self starting" may have several different interpretations, though. A "black start" generator could be deemed as being self starting, even though this initial power is (usually) supplied by a set of batteries. Many generators pull this power from the power grid, so if the grid is not energized (black start conditions), these generators cannot start until at least part of the power grid is put back in service with another generator.
