What are the advantages and disadvantages of wound rotor over squirrel cage rotor in case of induction motor?

What are the advantages and disadvantages of wound rotor over squirrel cage rotor in case of induction motor?

As a result the inrush current is reduced. 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.

Why the wound rotor induction motor is rarely used?

Poor starting torque and cannot be improved. The rotor is wound rotor type with its terminal ends connected to 3 slip rings on the output shaft. The rotor is skewed rotor type with its terminals are short-circuited at end rings.

How the wound rotor on an AC induction motor achieves a high starting torque?

Wound rotor motors are also referred to as “slip ring motors.” During starting, this resistance is placed in series with the rotor windings. This added resistance causes the rotor current to run more in phase with the stator current, which increases the torque that is developed.

What is the main advantage of the 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 advantage of a wound rotor induction motor to a squirrel cage induction motor?

The wound-rotor motors have the following advantages over the squirrel cage motors : (i) High starting torque and low starting current. (ii) Smooth acceleration under heavy load. (iii) No abnormal heating during starting.

Why many are much prefer to use squirrel cage over wound rotor type induction motor?

One big advantage of a squirrel cage motor is how easily you can change its speed-torque characteristics. This can be done by simply adjusting the shape of the bars in the rotor. Squirrel cage induction motors are used a lot in industry – as they are reliable, self-starting, and easy to adjust.

What are its advantages and disadvantages of wound rotor type 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.

What are wound rotor motors used for?

These motors are used with high inertia loads. Wound Rotor Induction Motor is used in applications which require smooth start and adjustable speed. Some of the applications of this motor include cranes, mills, hoists and conveyors. Wound rotor induction motor is also used in fans, blowers and mixers.

What is the rotor winding for wound rotor motors?

3 phase windings
1. What is the rotor windings for wound rotor motors? Explanation: The rotor windings for wound rotor motors are 3 phase windings.

Where are wound rotor motors used?

Wound Rotor Induction Motor is used in applications which require smooth start and adjustable speed. Some of the applications of this motor include cranes, mills, hoists and conveyors. Wound rotor induction motor is also used in fans, blowers and mixers. They are used in large pumps in water industry.

What is the rotor windings for wound rotor motor?

What is the rotor windings for wound rotor motors? Explanation: The rotor windings for wound rotor motors are 3 phase windings. The number of rotor slots should be such that a balanced winding is obtained. 2.

What is a wound rotor induction motor and how does it work?

A wound rotor induction motor has a stator like a squirrel cage induction motor, but a rotor with insulated windings brought out via slip rings and brushes. However, no power is applied to the slip rings. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting (figure below).

How does rotor resistance affect torque in a wound rotor motor?

When reaching synchronous speed, the rotor resistance can also be shorted, making the wound rotor motor behave as if it was a squirrel cage motor. Figure 2 shows the effect of increasing rotor resistance on output torque. Figure 2: How varying rotor resistance affects starting and pullout torque.

How does a rotor motor reduce the inrush current?

As the motor reaches its rated speed, the rotor generates a “back EMF” into the stator, which lowers the stator current back down to rated levels. The inrush current is what is minimized in wound rotor motors by increasing the resistance in the rotor windings (I=V/R, where R is increased), and why they have such smooth starting characteristics.

What are the advantages and disadvantages of a shorted rotor?

A shorted rotor operates like a squirrel cage rotor. The heat generated during starting is mostly dissipated external to the motor in the starting resistance. The complication and maintenance associated with brushes and slip rings is a disadvantage of the wound rotor as compared to the simple squirrel cage rotor.