0
Add your answer:
Earn +20 pts
What is the formula for calculating working pressure?
my question is what is the formula for pressure?
Where does the voltage that is necessary for field excitation on the rotor originates from?
The excitation current is provided by a small self-excited pilot generator, attached to the same shaft as the alternator's rotor.
What is the expression for calculating maximum current through the zener diode?
the expression for calculating maximum current through the zener diode is : Izmax=Pzmax / Vz
What effects causes the difference in terminal voltage between the increasing and decreasing field excitation current?
sdrg
What is the formula for calculating transformer oil in kg to liter?
316
What is the formula for calculating ratio analysis?
Ratio Analysis = Current Asset / Current Liabilities
What is the formula for excitation voltage?
E=Vt + Ia jXS Where E excitation voltage Vt Terminal voltage Stator Current Ia Xs synchronous Reactance
What is the formula for calculating the full load current of 3kW motor?
The formula you are looking for is I = Watts/ Voltage, I = 3000/voltage.
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 formula of calculating effective current if resistor and voltage is given?
I = E/R or Current = Voltage/Resistance (Ohm's Law)
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
Why The Excitation current is non-sinusoidal when applied voltage is sinusoidal?
excitation voltage is sinusoidal because it is taken from the terminal of alternator but excitation current is non-sinusoidal because it always dc.
In synchronous motor theory is excitation current the same as field current?
Yes, in synchronous motor theory, excitation current is the same as field current. This current is used to produce the magnetic field in the rotor that interacts with the stator current to generate torque and make the motor operate synchronously.
How do you calculate excitation frequency?
Excitation frequency can be calculated as the reciprocal of the excitation period, which is the time interval between two consecutive excitations. The formula is: Excitation frequency = 1 / Excitation period. Alternatively, if you know the excitation waveform (e.g., sine wave), you can determine the excitation frequency from the period of that waveform.
Equation for calculating current?
There are a great many equations for calculating current; it depends on the context in which you need to calculate current.
Why does the no-load characteristic differ for increasing and decreasing excitation current?
The no-load characteristic of a generator differs for increasing and decreasing excitation current due to magnetic hysteresis, residual magnetism, and core saturation effects. When the excitation current increases, the magnetic domains in the iron core gradually align with the applied magnetic field, resulting in a higher generated electromotive force (EMF). However, as the excitation current decreases, these magnetic domains do not immediately return to their original unaligned state. This lag in realignment causes the generated voltage to remain higher during the decreasing phase of excitation than during the increasing phase at the same level of excitation current. This phenomenon is known as magnetic hysteresis. Even when the excitation current is zero, the magnetic core retains some level of magnetisation, known as residual magnetism. This residual magnetic field means that when the excitation current starts increasing again, it takes additional current to overcome this residual alignment before the generated voltage rises significantly. As a result, the voltage is initially lower when increasing the excitation current from zero. Conversely, during the decreasing phase, the residual magnetism keeps the voltage higher than it would be if the core were fully demagnetised, further contributing to the difference between the increasing and decreasing curves. As the excitation current increases, the magnetic core of the generator approaches saturation. Near saturation, any further increase in excitation current results in only a small increase in generated voltage because the core's magnetic domains are almost fully aligned. When the excitation current decreases from this saturated state, the magnetic domains gradually return to a less aligned state. This gradual realignment causes the generated voltage to decrease differently than it increased, contributing to the asymmetry between the increasing and decreasing excitation phases.
