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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%.
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.
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
What is the function of ACtoAC convertor in doubly fed induction generator?
The Doubly Fed Indcution Generator (DFIG) is a very popular machine, since the output of the stator terminals is already at 60hz (no change in voltaje or frequency necessary). The matrix converter is used in the rotor side (wound rotor) in order to control the frequency and voltage magnitud to make the induction machine generate power at a wide range of speeds...
Why does the rotor of an induction motor turn slower than the revolving field?
In an induction motor the rotor currents are induced by the magnetic field of the stator, and if the motor were to run at synchronous speed the induced currents and also the torque would fall to zero. The rotor currents alternate at a low frequency determined by the 'slip', which is the percentage amount that the rotor speed is below the synchronous speed. The output torque is proportional to the slip at near-synchronous speeds.
