It depends on the number of poles and the frequency of the power. A two pole motor running on 60 Hz would rotate at 1800 RPM.
Synchronous motors have no slip. This is because the rotor runs at the same speed as the speed of the rotating magnetic flux of the stator.
A synchronous motor can operate as either a Generator or a Motor.When a synchronous motor has current applied to the windings on its rotor and the stator is energized with say a 50hz line supply (with little or no physical load) then the exact amount of excitation provided by the rotor can determine whether the stator displays inductive or capacitive properties.If the rotor is under excited (too Little rotor current) the Synchronous Motor will behave as an Inductor, however if the rotor is over excited then the Synchronous Motor will behave like a Capacitor.Hope this helps
synchronous motor is a constant speed motor because it will only run at a synchronous speed or not at all.the speed can be changed by changiing the frequency only ns=120f/p
When rotor speed becomes equal to Synchronous speed in an induction motor, it means that the slip is zero. Which means that there is no cutting of magnetic lines by rotor bars and hence no torque is generated. To generate Torque, rotor speed should always be less than the synchronous speed. That is why, you must have seen in your dailty life that all induction motors are rated below 3000 RPM(sync speed for a 2 pole machine). Sync speed (Ns) = 120f/P
Torque is produced because the rotating magnetic field, set up by the stator windings, cut and induce voltages into the rotor bars. The fields set up by the resulting rotor-bar currents then interact with the rotating field, causing the rotor to turn. If the rotor turns at the same speed as the rototing field, then its bars will not be cut by the field, there will be no induced voltages, no bar currents, and the torque will disappear.
Synchronous motors have no slip. This is because the rotor runs at the same speed as the speed of the rotating magnetic flux of the stator.
induction motor never runs at synchronous speed, if it does so there would not be any relative speed between stator flux and rotor and no emf will induce in rotor and we can not apply motor principle as we need current carrying conductor in magnetic field.
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.
For exactly the same reason as three-phase motors always run below synchronous speed. If they were to run at synchronous speed then no voltage and, therefore, no rotor current will be induced into the rotor to drive it.
only synchronous motor
Slip is the difference between the rotor speed and synchronous speed, expressed as a percentage of the synchronous speed (it can also be expressed as a per unit value). So when the rotor is stationary, its slip is 100% (or 1); if it were able to achieve synchronous speed (it can't!) then is slip would be 0% (or 0).
1)Synchronous motors are those that run only at Synchronous speed i.e. constant speed. But Motor can run in various speeds. 2)Synchronous motors runs at same speed of magnetic filed. but if one consider case of induction motor the rotor rotates at different speed than revolving magnetic field. there is slip between field and rotor.
An induction motor cannot run at synchronous speed because it is the "slippage" of the rotor relative to the rotaing magnetic field that generates the current in the windings contained within the rotor. This induced (hence the term induction) current sets up the opposing magnetic fields that cause the rotor to rotate.
As per the operating principle of the Synchronous motor, due to continuous & rapid rotation of stator poles,the rotor is subjected to a torque which is rapidly reversing i.e. in quick succession,the rotor is subjected to torque which tends to move it first in one direction & then in the opposite direction.Owing to its large inertia,the rotor cannot instataneously respond to such quickly-reversing torque,with the result that it remains stationary or in other words it is not self starting.
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.
A synchronous motor can operate as either a Generator or a Motor.When a synchronous motor has current applied to the windings on its rotor and the stator is energized with say a 50hz line supply (with little or no physical load) then the exact amount of excitation provided by the rotor can determine whether the stator displays inductive or capacitive properties.If the rotor is under excited (too Little rotor current) the Synchronous Motor will behave as an Inductor, however if the rotor is over excited then the Synchronous Motor will behave like a Capacitor.Hope this helps
in case of induction motor the rotor speed is less than synchronous speed giving positive slip but in case of generator the rptor speed is greater than synchronous speed giving negative slip.......