Table of Contents
High Starting torque with low starting current. Maximum starting can be attained in the slip ring motor compared to squirrel cage motor by inserting an external resistance in each phase of the rotor circuit and cutting the resistance during starting.
What is the advantage of starting of slip ring induction motor with the help of rotor resistance as compared to other method?
The slip ring induction motor has a high starting torque as the resistance of the rotor winding is increased by adding the external resistance to it. The starting torque is increased as the power factor of the rotor circuit gets improved during starting.
What are the advantages and disadvantages of wound rotor induction motor?
Wound Rotor Induction Motor Qualities Excellent starting torque for high inertia loads. Low starting current compared to squirrel cage induction motor. Speed is the resistance variable over 50% to 100% full speed. Higher maintenance of brushes and slip rings compared to squirrel cage motor.
What is the principle of slip ring induction motor?
This motor runs on the principle of Faraday’s law of electromagnetic induction. When a stator winding is excited with an AC supply, the stator winding produces magnetic flux. Based on faraday’s law of electromagnetic induction, the rotor winding gets induced and generates a current of magnetic flux.
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 the advantages of slip ring induction motor?
Speeds can be adjusted in the case of slip ring (wound rotor) induction motor by inserting an resistance. Hence slip ring motors are considered as variable speed motors. Slip ring motors have high over loading capacity, smooth acceleration under heavy loads, and no abnormal heating during starting.
Why slip rings are used in induction motor?
In a version of the AC induction motor referred to as a wound rotor motor, slip rings are used not for transferring power, but for inserting resistance into the rotor windings. As the slip rings turn with the rotor, the brushes maintain constant contact with the rings and transfer the resistance to the rotor windings.
What advantages does the wound rotor motor offer?
Another important advantage over squirrel-cage motors is higher starting torque. The speed and torque characteristics of a wound-rotor motor can be adjusted by changing the external resistance, unlike a squirrel cage motor which has a fixed characteristic. This is useful for speed control of the motor.
Why rotor slots are skewed?
The rotor or stator slot of the induction motor skewed through some angle so that the bars lie under alternate harmonic poles of the same polarity or other words, bars must be skewed through two pitches. The main purpose of skewing is to reduce the magnetic logging between the starter and the rotor.
What is the difference between induction motor and transformer?
A transformer transfers electrical power from one circuit to another without changing the supply frequency, i.e. it only step-up or step-down the level of voltage and current, whereas induction motor converts electrical power into mechanical power.
What is the function of slip ring in 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.
Is slip ring a commutator?
A commutator is a specialized slip ring typically used on Direct Current motors and electrical generators to transfer electrical power between the stationary housing and the rotating armature with the added purpose of reversing the electrical current direction.
What is the unit of slip in induction motor?
The slip value is equal to ‘1’ as the rotor in the motor is at rest & it will not equivalent to ‘0’. So while operating the motor, the synchronous speed is not equivalent to ‘N’ i.e, actual speed in a given time. This article discusses an overview of the slip in an induction motor.
Which starter is used for slip ring induction motor of high ratings?
For slip ring induction motors with high ratings, a rotor resistance starter is utilised.
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.
Why are slip rings used?
“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 unrestrained, intermittent or continuous rotation while transmitting power and / or data.
What are the advantages of slip system?
The advantages of this system are: ADVERTISEMENTS: (i) it reduces the possibility of errors and frauds; (ii) it saves a lot of time since it is prepared by the customers themselves; (iii) it provides a good system of internal check etc.
What are the applications of induction motor?
These are the most common type of AC motor and are important to industry due to their load capacity, with Single-Phase induction motors being used mainly for smaller loads, for example in household appliances whereas, Three-Phase induction motors are used more in industrial applications including compressors, pumps, May 5, 2016.
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 happens if the slip of induction motor is 1?
This is the reason; slip is never zero in an induction motor. Slip = 1, means that rotor is stationary. Negative value of slip in induction motor can be achieved when the rotor speed is more than the synchronously rotating magnetic flux.
What is slip in DC motor?
Slip is the differentiation between synchronous and asynchronous speed. An AC (Alternating Current) induction motor consists of a stator and a rotor and the interaction of the currents flowing in the rotor bars and the rotating magnetic field in the stator generates the torque that turns the motor.
What is the drawback of rotor Rheostatic speed control method?
The major disadvantage of the rotor resistance control method is that the efficiency is low because of the additional losses present in the resistors connected within the rotor circuit. The efficiency is greatly reduced at low speeds because of the higher value of the slip.
What is slip in 3 phase induction?
“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.
Why will the rotor of a wound rotor motor not turn if the rotor circuit is left open with no resistance connected to it?
If the circuit is left open, the current will not flow in the rotor, this leads to the absence of the magnetic field in the rotor. Therefore, there will be no torque between the rotor and the field. Hence, the motor will not start.
