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Why The Excitation current is non-sinusoidal when applied voltage is sinusoidal?
Wiki User
∙ 14y ago
excitation voltage is sinusoidal because it is taken from the terminal of alternator but excitation current is non-sinusoidal because it always dc.
Wiki User
∙ 14y ago
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Why the rotor of an alternator at rated power dissipates more heat at a low power factor load?
In an alternator, the load current is supplied by the stator and the excitation is applied to the rotor. When the power factor is low (lagging), more excitation is required to maintain rated output voltage at rated current. More excitation is also required to maintain rated output voltage with increased output current. Increased excitation current means increased rotor losses that must be dissipated as heat. (akash)
What is transformer turns ratio excitation current?
This is the current level needed to energize a transformer to its rated voltageThe clue is in the name! 'Excitation' means to create a magnetic field. So the excitation current is the current drawn from the supply which sets up the magnetic field around the core.
What is the difference between generator over excitation versus under excitation when attached to the grid?
Over Excitation is a condition when the Excitation System is providing too much field current and as a result, the rotor of the generator will over heat. The Excitation System is equipped with an Over Excitation Limiter. This limiter acts to reduce the Excitation Current if this condition exists Underexcitation is a condition when the generator is not getting enough Excitation Current. If the generator does not get enough Excitation Current, it can be un-synchronized with the grid. We call this slipping a pole. If this occurs, the generator can be severely damaged. Kelly Thompson Engineering Lead Siemens Energy Alpharetta GA
No load current of transformer is non sinusoidal even though sinusoidal voltage is provided in oc sc test?
eddy current loss in the transformer core is reduced by
What is the excitation system in a generator used for?
The excitation system is used to control the excitation of the rotating field in the armature. By increasing the armature current, it in turn increases the magnetic flux in the armature coil. This has the effect of increasing the voltage output of the generator. By lowering the armature current this in turn lowers the generator output voltage. The generator's voltage regulator automatically adjusts the output voltage continuously as the applied load on the generator changes.
What is nonsinusoidal currents?
"nonsinusoidal current" is any current that is not sinusoidal - it could be a wave such as a square wave, triangle wave, etc. DC (direct current) is non sinusoidal. This term is often used in reference to currents that you "would expect" to be sinusoidal (such as the current to your house is sinusoidal at 50 or 60 hz) but aren't - such as transformer inrush current, magnetizing currents,...any current with large amounts of harmonics. AC current is also (generally) not sinusoidal due to the way power supplies only conduct from the input when the rectifier filter capacitor needs to be recharged during each line cycle. That results in a pulsing current, even though the voltage is mostly sinusoidal.
What is the science behind the alternating current?
When a sinusoidal alternating voltage is applied in a circuit, the resulting alternating current is also sinusoidal and has the same frequency as that of applied voltage .However, there is generally a phase difference between the applied voltage and the resulting current.This is how alternating-current circuit works. If you want more ,send message
In synchronous motor theory is excitation current the same as field current?
yes. excitation current is same as field current to my knowledge
Why the rotor of an alternator at rated power dissipates more heat at a low power factor load?
In an alternator, the load current is supplied by the stator and the excitation is applied to the rotor. When the power factor is low (lagging), more excitation is required to maintain rated output voltage at rated current. More excitation is also required to maintain rated output voltage with increased output current. Increased excitation current means increased rotor losses that must be dissipated as heat. (akash)
What is transformer turns ratio excitation current?
This is the current level needed to energize a transformer to its rated voltageThe clue is in the name! 'Excitation' means to create a magnetic field. So the excitation current is the current drawn from the supply which sets up the magnetic field around the core.
What components compose the excitation current of transformer how the are modeled in the transformer's equivalent circuit?
Excitation current Io = Iw + Iu
What is the difference between generator over excitation versus under excitation when attached to the grid?
Over Excitation is a condition when the Excitation System is providing too much field current and as a result, the rotor of the generator will over heat. The Excitation System is equipped with an Over Excitation Limiter. This limiter acts to reduce the Excitation Current if this condition exists Underexcitation is a condition when the generator is not getting enough Excitation Current. If the generator does not get enough Excitation Current, it can be un-synchronized with the grid. We call this slipping a pole. If this occurs, the generator can be severely damaged. Kelly Thompson Engineering Lead Siemens Energy Alpharetta GA
No load current of transformer is non sinusoidal even though sinusoidal voltage is provided in oc sc test?
eddy current loss in the transformer core is reduced by
What is the formula for calculating excitation current?
there is none
What is the excitation system in a generator used for?
The excitation system is used to control the excitation of the rotating field in the armature. By increasing the armature current, it in turn increases the magnetic flux in the armature coil. This has the effect of increasing the voltage output of the generator. By lowering the armature current this in turn lowers the generator output voltage. The generator's voltage regulator automatically adjusts the output voltage continuously as the applied load on the generator changes.
Why does the no-load characteristic differ for increasing and decreasing excitation current?
No-load characteristic knows as magnetic characteristic or open circuit Characteristic (O.C.C). It shows the relation between the no-load generated e.m.f in armature, E and the field or exciting current Im at a given fixed speed. The excitation voltage is directly proportional with excitation current. When excitation voltages increase so do excitation currents also increase.
What are the phasor diagrams and sinusoidal expressions of the three voltages?
The Phasor diagram explains the relation between voltage and current. This comparison happened in the Sinusoidal functions and solved using the Sinusoidal expression.
