Why does the voltage & frequency induced into the rotor of an induction motor decrease as the rotor speeds up?

Above rated speed, V/Hz will reduce because voltage is kept constant at rated motor voltage, stator, and rotor current are also kept constant and speed and frequency are increasing, so the flux density will reduce and the torque will reduce inversely with the frequency.

What is the frequency of induced emf in the rotor of an induction motor?

The frequency of the induced emf in rotor is? Explanation: The induced frequency will be f = P(Ns-Nr)/2. f = 4(1500-1450)/2 = 100 Hz. 3.

Why the rotor speed of an induction motor is less than its synchronous speed?

An induction motor always runs at a speed less than synchronous speed because the rotating magnetic field which is produced in the stator will generate flux in the rotor which will make the rotor to rotate, but due to the lagging of flux current in the rotor with flux current in the stator, the rotor will never reach . …

Does the frequency of rotor induced emf changes when the rotor rotates?

It appears that the rotor rotates in the same direction as the stator rotating field. As the rotor increases in speed the relative speed difference between the stator field and rotor is reduced. As a result the emf ER1 decreases as does the rotor frequency fR.

What is the frequency of induced emf?

The induced emf frequency is slip times the frequency of applied voltage. Since emf in induction motor is induced when stator flux cut the rotor conductor so the emf actually is induced only due to their relative speed i.e Ns-Nr (Ns=synchronous speed of stator flux and Nr=rotor speed in RPM) between them.

What is rotor frequency?

The frequency of the rotor current fr = Ns x P/120, so fr = 0 if the slip is zero. If the operating speed is zero, Ns = N and the frequency of the rotor current is the same as the frequency of the stator current .

When rotor speed is less than synchronous speed?

The actual rotor speed is always less than synchronous speed so as to produce current in the rotor bars. Two terms are used to define relative motion between rotor and rmf. One of them is slip speed. Slip speed is defined as the difference between synchronous speed and rotor speed.

What is rotor induced emf?

3 Rotor induced e.m.f. and current. The rate at which the rotor conductors are cut by the flux, and hence their induced e.m.f., is directly proportional to the slip, with no induced e.m.f. at synchronous speed (s = 0) and maximum induced e.m.f. when the rotor is stationary (s = 1).