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The stator's coils in a (induction) motor produce a (first) magnetic field pattern, rotating at the supply frequency, F(s).
This flux is cut by the rotor conductors because it's turning relatively slower than the rotating field (slip, s, is not zero).
Induced currents are therefore creating a (second) induced magnetic field pattern around the rotor's condutors which is revolving at a relative (rotor) frequency F(r).
F(r) = s * F(s)
This is sometimes called slip frequency.
What else can I help you with?
When induction motor is switched on the rotor frequency is?
The induction motor rotor has different frequency compared to it's stator. The rotor has slip ( s ) frequency. slip = ( Synchronous speed - rotor speed ) / Synchronous speed Synchronous speed = ( 120 * f ) / P where f = supply frequency to the stator. p = no of poles rotor speed is the actual speed the motor is running. Frequency in the rotor = slip * frequency in the stator At starting rotor speed is zero, so slip is one. Let us take the supply frequency is 50 Hz, then rotor frequency is also 50 Hz at starting. The motor attains speed and runs with its full speed at a point of time. Then let us take the slip is 0.04 then the rotor frequency will be 2 Hz.
How does a high frequency induction motor work?
A high frequency induction motor uses high frequency electrical currents to create a rotating magnetic field in the stator. This rotating field induces currents in the rotor, which causes it to rotate and drive the motor. The higher frequency allows for more precise speed control and efficiency in certain applications.
Frequency of emf generated per rotation of rotor is equal to?
The frequency of emf generated per rotation of the rotor depends on the number of poles on the rotor and on the field. Please restate your question. For the two pole / two pole case, an atypical configuration, but good for illustration, 3,600 RPM would generate 60 Hz.
Does the value of the exciting current of your 3-phase motor depend on the rotor speed?
An induction motor has no excitation, so the question is about a synchronous motor. The rotor speed is determined by the supply frequency. For a given supply frequency and mechanical load, the excitation current can be adjusted to give the best power factor.
What is the working principle of Doubly Fed Induction Generator?
The principle of the DFIG is that rotor windings are connected to the grid via slip rings and back-to-back voltage source converter that controls both the rotor and the grid currents. Thus rotor frequency can freely differ from the grid frequency (50 or 60 Hz). By using the converter to control the rotor currents, it is possible to adjust the active and reactive power fed to the grid from the stator independently of the generator's turning speed.
What is difference between frequency and slip frequency?
Both 3-phase induction motors and single-phase induction motors have rotating magnetic fields assuming that the single-phase motor has one of the usual starting mechanisms built-in. The synchronous speed is given by RPM = 120 X f / p where f is the frequency and p is the number of poles. The conductors in the rotor pass through the magnetic field of the stator at the slip speed. As a result an alternating current is generated in the rotor. The frequency of that current is the rotor frequency or slip frequency given by slip frequency = slip speed X p / 120. At full load, the slip speed of a standard, 3-phase motor is about 1% to 2.5% of synchronous speed. A motor with 6% slip would be classified as a high-slip motor. The slip of a standard single-phase motor could be 6%.
What you mean by stater voltage control stater frequency control and also rotor voltage control?
Stator voltage control refers to the regulation of the voltage supplied to the stator windings of an electric motor or generator, which directly influences its torque and speed. Stator frequency control involves adjusting the frequency of the voltage supplied to the stator, typically using variable frequency drives (VFDs), to control the speed of the motor. Rotor voltage control, often used in induction machines, entails adjusting the voltage applied to the rotor to manage its performance and efficiency, particularly during starting or variable speed operations. Together, these controls help optimize the operation of electric machines in various applications.
Why field windings of synchronous alternator are excited by dc?
The 'field'winding is in the rotor which rotates at the synchronous speed generating AC powerat the right frequency in the stator. That requires DC in the rotor. It is convenient because the DC is supplied to the rotor through slip rings, smooth polished rings which allow the carbon brushes to last a long time.
Can frequency be adjusted on a ac generator?
Yes, the frequency of an alternating current (AC) generator can be adjusted, but it typically depends on the speed of the generator's rotor. In synchronized generators, the frequency is directly related to the rotational speed and the number of poles; increasing the speed raises the frequency, while decreasing it lowers the frequency. Additionally, some advanced systems may use electronic controls to manipulate the output frequency, but mechanical adjustments are more common in traditional generators.
What is a reverse KVAR relay?
The reverse KVAR relay protects a generator from a loss of excitation. When the excitation system is lost, reactive power will flow from the system back into the generator. When this happens, induced currents at twice the system frequency will flow in the rotor windings and rotor structure.
Why an induction motor will never run at synhoronous speed?
An induction motor relies on low-frequency currents induced in the rotor by the difference in speed between the rotor and the rotating magnetic field. At sychronous speed the induced current is zero therefore the torque is also zero.
Why induction motor runs slightly slower than supply frequency?
if the motor is at synchronous frequency there is no current induced in the shorted windings in the rotor so at no load its slightly less. if you drive the motor faster than synchronous speed it becomes a generator
