Efficiency of a motor is the ratio of power supplied to it, to the power produced by it, expressed as a percentage. This varies from motor to motor. It is calculated using the equation: efficiency = ((Pin - Pout) / Pin) * 100
A typical power conversion efficiency for an induction motor over ½ HP would be 90%
CommentEfficiency is actually the ratio of output power to input power, not the other way around!
No, it is not necessary to have three-phase rotor windings for a transmitter and motor in a selsyn motor. Selsyn motors typically use single-phase rotor windings to transfer information or control signals between devices. The synchronization between the transmitter and motor is achieved through the interaction of the stator and rotor windings.
If the frequency supplied to a three-phase motor is increased, the motor speed will also increase following the relationship known as the synchronous speed. This increase in frequency will lead to a corresponding increase in motor speed, assuming that the load on the motor remains constant.
A motors locked rotor current is the same as the motors starting current. This is the point where the voltage is applied to a non rotating motor, time cycle zero. Because the motor is not rotation and generating a back EMF to oppose the inrush current, the current will go as high as 6 times the running current of the motor.
To use a single/one phase motor instead of a three phase motor is possible if you have a three phase power supply as you will only need to tap one of the three phases together with neutral and an earthwire, however to use a three phase motor instead of a single phase will require the provision of three phase power supply.
For a 240-volt single-phase induction motor, a two-pole motor starter is typically required, as it connects to the two live conductors of the single-phase supply. For a 440-volt three-phase induction motor, a three-pole motor starter is needed, as it connects to the three phases of the three-phase supply.
No, it is not necessary to have three-phase rotor windings for a transmitter and motor in a selsyn motor. Selsyn motors typically use single-phase rotor windings to transfer information or control signals between devices. The synchronization between the transmitter and motor is achieved through the interaction of the stator and rotor windings.
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.
Wire, bearings, rotor and stator.
You don't.
A three-phase motor has a steady rotating magnetic field generated by the stator coil, and the rotor just follows the field.
Slip is the relative difference between the speed of the rotating magnetic field of the stator windings and the speed of the rotor. The rotor must always run at a speed lower than the synchronous speed otherwise the rotor windings will not be cut by the magnetic field and hence no induced emf,no torque and the rotor will stand idle.
Induction motor is nothing but rotating transformer it works on principle of mutual induction , mainly induction motor consists of rotor and stator,stator is excited by three phase supply and rotor is shorted through resistances and slip rings. When ever stator is excited by three phase supply a rotating magnetic field running at synchronous speed is produced which in turn cuts the rotor winding causes flowing of current results in production of magnetic fields in rotor which having less than synchronous speed (slip speed), then the interaction of these stator and rotor magnetic fields produces a twisting moment in the rotor called synchronous speed
If the frequency supplied to a three-phase motor is increased, the motor speed will also increase following the relationship known as the synchronous speed. This increase in frequency will lead to a corresponding increase in motor speed, assuming that the load on the motor remains constant.
When three phase supply is given to the three phase stator winding of the induction motor,a rotating magnetic field is developed around the stator which rotates at synchronous speed.This rotating magnetic field passes through the air gap and cuts the rotor conductors which were stationary.Due to the relative speed between the stationary rotor conductors and the rotating magnetic field,an emf is induced in the rotor conductors.As the rotor conductors are short circuited, current starts flowing through it.And as these current carrying rotor conductors are placed in the magnetic field produced by the stator, they experiences a mechanical force i.e. torque which moves the rotor in the same direction as that of the rotating magnetic field. the induction motor can't run at the synchronous speed because at synchronous speed the induction motor can not develop any torque to move the rotor from its stationary position.
A synchronous motor is a three phase motor, which uses a magnetic field created by permanent magnets or a DC electromagnet on the rotor (usually). The stator windings have 3 phase voltages applied, and coupled with the DC field, create a rotating magnetic field that drives the motor at synchronous speed.
If the synchronous motor is single phase then there are two slip rings & if this motor is three phase so the slip rings are three in number. Correction; I have never seen a single phase synchronous motor. It would cost more that it was worth. A synchronous motor has a separately excited field. If the excitation comes from a stationary DC source it has 2 slip (collector) rings. A brushless induction motor has no slip rings because the exciter armature rotates and so do the rectifiers. A permanent magnet motor, used with variable frequency drives, is another type of synchronous motor that has no slip rings. A three phase motor with 3 slip rings is a Wound Rotor motor. Wound rotor motors are variable speed motors that were used for such applications as bridges and cranes before variable speed drives.
Star and delta connection