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Key Differences Between Slip Ring & Squirrel Cage Induction Motor. The motor whose rotor is wound type such type of motor is called slip ring induction motor, whereas the squirrel cage motor, has a squirrel cage type rotor. The starting torque of the slip-ring motor is high, whereas in squirrel cage motor it is low.
What is the difference between squirrel cage induction motor?
In 3 phase slip ring induction motor, the rotor resistance starter is used. When low starting torque is required, the squirrel cage motor is used. When high starting torque is required, the slip ring motor is used. Better cooling is available in this type of motor due to the presence of more space in rotor slots.
What are the advantages of slip ring induction motor compare to the squirrel cage induction motor *?
Induction motors generally will have low starting torque compared to dc series motor. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor. Therefore slip ring induction motors are generally employed where load requires high starting torque or good speed control.
What’s the difference between squirrel cage and wound rotor?
The major difference is the external resistance circuit for controlling the speed of the motor. In the case of squirrel cage induction motor, rotor bars are short-circuited with end rings. Therefore, the external resistance cannot connect with the rotor.
What is slip ring in induction motor?
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 are the advantages of squirrel cage motor?
Some advantages of squirrel cage induction motors are: Simple and rugged construction. The low initial as well as the maintenance cost. Maintains constant speed. The overload capacity is high. Simple starting arrangement. High power factor. Low rotor copper loss.
Why is it called squirrel cage motor?
Squirrel cage motors are a subclass of induction motors, which harness electromagnetism to generate motion. They are so-called “squirrel cage” motors because the shape of their rotor – the inner component connected to the output shaft – looks like a cage.
Why is squirrel cage induction motor preferred?
Advantages of Squirrel Cage Induction Motor They are low cost. Require less maintenance (as there are no slip rings or brushes) Good speed regulation (they are able to maintain a constant speed) High efficiency in converting electrical energy to mechanical energy (while running, not during startup)Aug 19, 2020.
Which is better squirrel cage or slip ring?
The squirrel cage induction motor is the most popular type of AC motor. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable.Comparison Chart. Basis For Comparison Slip Ring Motor Squirrel Cage motor Power Factor Low HIgh Cost Costly Cheap Starting Current Low High.
What are the applications of slip ring induction motor?
Slip ring induction motor is one of the types of 3-phase induction motor and is a wound rotor motor type. Because of various advantages like low initial current, high starting torque, and improved power factor, it is used in applications that require high torque, cranes, and elevators.
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.
Why squirrel cage rotor is skewed?
Skewing. The conductors are often skewed slightly along the length of the rotor to reduce noise and smooth out torque fluctuations that might result at some speeds due to interactions with the pole pieces of the stator, by ensuring that at any time the same fraction of a rotor bar is under each stator slot.
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 we use slip rings in motors?
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 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 type of starter is used in slip ring induction motor?
Rotor resistance starter is used for slip ring induction motors of high ratings.
What is the disadvantages of squirrel cage motor?
Main disadvantage of squirrel cage induction motor is that they have poor starting torque and high starting currents. Starting torque will be in the order of 1.5 to 2 times the full load torque and starting current is as high as 5 to 9 times the full load current.
What are the advantages of double squirrel cage induction motor?
The advantage of a double-squirrel cage motor is that it provides high starting torque and low starting current.
Why is the speed of the squirrel cage motor fixed?
‘Fixed’ speed induction generators Because the speed variation from no load to full load is very small, the term ‘fixed’ speed tends to be widely used. The design and construction of the stator and rotor of an induction generator are similar to that of a large induction motor having a squirrel-cage rotor.
What type of starter Cannot be used for squirrel cage motors?
So we cannot use is this method for starting. Important Points: The star-delta starter method of starting three-phase induction motors is very common and widely used among all the methods.
Why do squirrel cage motors have low starting torque?
It suffers from the disadvantage of a low starting torque. It is because the rotor bars are permanently short-circuited and it is not possible to add any external resistance to the rotor circuit to have a large starting torque.
How is the direction of rotation of a squirrel cage motor reversed?
The direction of rotation of these motors can be easily changed. This is accomplished by reversing the connections of two of the power lines to the motor leads. The result is the rotating magnetic field will reverse, and the rotor will turn in that direction.
