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A wound-rotor motor, also known as slip ring-rotor motor, is a type of induction motor where the rotor windings are connected through slip rings to external resistance. Adjusting the resistance allows control of the speed/torque characteristic of the motor. Each pole is wired in series with a variable power resistor.
What is the purpose of slip ring in induction motor?
A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals.
What is the function of slip ring?
Slip rings: slip ring is a semi-circle shaped electrochemical device used to rotate a coil in the generator. The main function of these slip rings is to transmit electric power into a coil which is at rest to make it move or particularly rotate it.
Where are slip ring induction motors used?
The Slip ring induction motor possesses a high Starting Torque and low starting current. It is used mainly for: – Conveyors, Cranes, Compressors, Elevators, and Hoist etc.
What is difference between slip ring and commutator?
The main difference is that commutator is used for the conversion of AC to DC. Slip rings are used in AC motors to provide a continuous transfer of power whereas the commutators are used in DC motors to reverse the polarity of the current in the armature windings.
What is the difference between induction motor and slip ring motor?
In Squirrel cage induction motors the rotor is simplest and most rugged in construction. In slip ring induction motors the rotor is wound type. In the motor the slip rings, brushes are provided. Compared to squirrel cage rotor the rotor construction is not simple.
What is the slip?
Slip is the differentiation between synchronous and asynchronous speed. The difference between the synchronous speed of the electric motor magnetic field, and the shaft rotating speed is slip – measured in RPM or frequency. Slip increases with increasing load – providing a greater torque.
What is slip formula?
If the revolving magnetic flux’s synchronous speed & the speed of rotor are Ns & Nr in the motor, then the speed among them can be equivalent to (Ns – Nr). So, slip can be determined as. S = (Ns – Nr) / Ns.
Why do AC generators have two slip rings?
Slip rings provide a means for connecting the rotating armature of a simple a.c. generator to an external circuit. As the armature naturally produces an alternating voltage, an alternating voltages appears across the slip rings. There are two coaxial metallic rings R1 and R2. They rotate along with the coil.
What is the difference between squirrel cage and slip ring induction motor?
The slip ring motor has brushes for transferring the power whereas the squirrel cage motor is brushless. The copper loss in the phase wound motor is high as compared to squirrel cage motor. The efficiency of the slip ring motor is low whereas the squirrel cage motor has high efficiency.
What is AC motor slip?
“Slip” in an AC induction motor is defined as: As the speed of the rotor drops below the stator speed, or synchronous speed, the rotation rate of the magnetic field in the rotor increases, inducing more current in the rotor’s windings and creating more torque. Slip is required to produce torque.
What type of starter is used in slip ring induction motor?
Rotor resistance starter is used for slip ring induction motors of high ratings.
Why do motors have brushes?
The function of the brushes is to conduct electricity to the individual segments as they rotate from brush to brush. This allows the motor to turn in one direction at a speed determined by the number of windings in the armature.
What are the main parts of 3 phase induction motor?
The stator of the three-phase induction motor consists of three main parts : Stator frame, Stator core, Stator winding or field winding.
Which type of motor uses slip rings?
A wound-rotor motor, also known as slip ring-rotor motor, is a type of induction motor where the rotor windings are connected through slip rings to external resistance. Adjusting the resistance allows control of the speed/torque characteristic of the motor.
Do DC motors have slip rings?
In a d.c electric motor, the commutators are used instead of slip rings. The commutators are similar to the slip rings but have critical distinctions. In the d.c motors, commutators are used to reverse the polarity of current in the armature coils.
What is difference between armature and commutator?
An armature is a combination of the winding, commutator, brushes, and ball bearings.What is Commutator? Armature Commutator It receives current from the armature windings It receives current from the armature core The core consists of armature windings, commutator, and brushes It has some segments.
What is end ring?
: the ring at either end of an induction motor rotor to which the copper or aluminum bars are connected.
What are the two types of rotors?
There are two types of induction motor rotors: Squirrel-cage rotor or simply cage rotor. Phase wound or wound rotors.
What are the applications of 3-phase induction motor?
Application of 3-Phase Induction Motors Pumps and submersible. Pressing machine. Lathe machine. Grinding machine. Conveyor. Flour mills. Compressor. And other low mechanical power applications.
What are types of induction motor?
Types of Induction Motors Split Phase Induction Motor. Capacitor Start Induction Motor. Capacitor Start and Capacitor Run Induction Motor. Shaded Pole Induction Motor.
What happens when slip is zero?
Zero slip means that rotor speed is equal to synchronous speed. If rotor is rotating at synchronous speed in the direction of rotating magnetic field the, there will be no flux cutting action, no emf in the rotor conductors, no current in rotor bar conductor and hence no development of electromagnetic torque.
What is slip speed?
The speed at which the induction motor work is known as the slip speed. The difference between the synchronous speed and the actual speed of the rotor is known as the slip speed. In other words, the slip speed shows the relative speed of the rotor concerning the speed of the field.
What is full load slip?
The slip corresponding to full load speed of th motor is called full load slip. Example 1 : A 4 pole, 3 phase induction motor is supplied from Hz supply. Determine its synchronous speed. On full load, its speed is observed to be 1410 r.p.m. calculate its full load slip.
