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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%.
Are the motor used in tape recorder are split phase?
AC motors are not suitable for tape recorders because the speed can not be kept sufficiently constant. Tape recorders use dc shunt-wound motors with electronic speed control.
Why use clutch plate in single phase motor?
induction motors have very little starting torque as the motor come up to speed it reduces the torque load until it gets near synchronous speed
Do all single phase motors have a start and run winding?
No, commutator motors as used in vaccum cleaners for example do not use a starting winding. Single-phase induction motors need a starting winding without which they will start in either direction if given an initial twist.
Examples of three phase balanced load used in industries?
* 3 phase motors * resistance heaters
Why single phase series motors have large number of poles?
All motors have a set number of poles for the speed they are designed to run at. 3600 rpm are 2 pole,1800 rpm are 4 pole, 1200 rpm are 6 pole, ect.
What are three phase motors?
Three phase motors are motors which operate under three phase supply.Each phase is displaced from one another by 120 degrees.It produces three fluxes which are also 120 degrees displaced.
Why is the speed of synchronous motor is more then induction motor?
Synchronous motors run at synchronous speed. An induction motor that has the same number of poles must run at a sub-synchronous speed to create a second magnetic field (a field that is at a different phase angle) to generate torque.
Why would three phase be used instead of single phase?
Three phase electricity is used instead of single phase for industrial situations. Industries use three phase electricity instead of single phase to operate electric motors driving heavy machinery. Three phase electrical motors produce more power from the same amount of electricity and maintain steadier speed. Small portable motors such as drills and mixers use single phase. Motors used around the house are single phase. Motors used to run large industrial machines use three phase.
Why single phase induction motor always runs below the synchronous speed?
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.
Are potential relays used to energize or de energize split phase motors?
Potential relays are used to energize the start winding of split-phase motors when the motor is starting up. They help provide the initial burst of power needed to get the motor running, and then de-energize once the motor is up to 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%.
Are the motor used in tape recorder are split phase?
AC motors are not suitable for tape recorders because the speed can not be kept sufficiently constant. Tape recorders use dc shunt-wound motors with electronic speed control.
Why 2 phase induction motors are not used in industries?
A two-phase* system is archaic, and has been completely superceded by three-phase systems, so there is no demand for two-phase induction motors. (*A two-phase generator has two phase windings, displaced from each other by 90 degrees.)
Why use clutch plate in single phase motor?
induction motors have very little starting torque as the motor come up to speed it reduces the torque load until it gets near synchronous speed
Which of the following phase changes is not correctly paired with the sign of its change in enthalpy?
The phase change of sublimation is not correctly paired with the sign of its change in enthalpy. Sublimation involves the transition from solid to gas phase without passing through the liquid phase, and it is an endothermic process where heat is absorbed. The other phase changes—melting (endothermic), freezing (exothermic), vaporization (endothermic), and condensation (exothermic)—are correctly paired with the sign of their change in enthalpy.
What has the author John A McCormick written?
John A. McCormick has written: 'Three-phase inverter for small high speed motors' -- subject(s): Refrigeration and refrigerating machinery
