What type of starter is used with a wound rotor induction motor?
Table of Contents
- 1 What type of starter is used with a wound rotor induction motor?
- 2 Why are the starters required for the starting of three phase induction motor?
- 3 Why will the rotor of a wound rotor motor not turn if the rotor circuit is left open with no resistance connected to it?
- 4 Why are starters needed?
- 5 What are the disadvantages of rotor resistance starter?
- 6 What is a wound rotor 3 phase motor?
- 7 What are the advantages of wound rotor induction motor?
What type of starter is used with a wound rotor induction motor?
Detailed Solution
| Slip ring induction motor | Squirrel cage induction motor |
|---|---|
| The rotor resistance starter can be used | Rotor resistance starter cannot be used |
| Starting torque is high | Starting torque is low |
| Brushes are present | Brushes are absent |
| Frequent maintenance is required | Less maintenance required |
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.
Why are the starters required for the starting of three phase induction motor?
The three phase induction motors are self-starting due to rotating magnetic field. But the motors show tendency to draw very high current at the time of starting. Hence there should be a device which can limit such high starting current. Such a device which limits high starting current is called a starter.
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.
Why will the rotor of a wound rotor motor not turn if the rotor circuit is left open with no resistance connected to it?
Explanation. 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.
What is wound type rotor?
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.
Why are starters needed?
Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.
Why is a starter needed for starting a large capacity induction motor?
Induction Motor As a result, the stator draws high current and by the time the motor reaches to full speed, a large amount of current (greater than the rated current) is drawn and this can cause heating up of the motor, eventually damaging it. To prevent this, motor starters are needed.
What are the disadvantages of rotor resistance starter?
Disadvantages of Rotor Resistance Starter
- Lower efficiency due to the I2R losses in the external resistance connected in the rotor circuit.
- This starter can only be used for starting a slip ring induction motor.
- It needs frequent maintenance due to presence of slip rings and carbon brushes.
What is the disadvantage of starting an induction motor with a star delta starter?
a ) The starter can only be applied to motors where the six leads or terminals can be accessed. b ) The supply voltage must be the same as the rated motor voltage for Delta connection.
What is a wound rotor 3 phase motor?
This type of 3-phase induction motor has high starting torque, which makes it ideal for applications where standard NEMA design motors fall short. The wound-rotor motor is particularly effective in applications where using a squirrel-cage motor may result in a starting current that’s
How does the stator of a three phase induction motor work?
The stator RMF rotates at full speed when a three-phase induction motor starts, while the rotor is initially at rest. The rotor experiences induced current when the RMF of the stator passes through it, and the only limiting factor to this current is the resistance of the rotor windings (current = voltage/resistance).
What are the advantages of wound rotor induction motor?
Widely used about 90\% of the industry uses squirrel cage induction motor. Some of the advantages of wound rotor induction motor are discussed below. High starting torque – Slip ring induction motor can provide high starting torque due to the presence of external resistance in the rotor circuit.
Why slip ring induction motor is called asynchronous motor?
The motor’s rotor is a type of wound rotor. Hence why it is also known as a wound rotor or phase wound induction motor. The speed at which a slip ring induction motor operates is not equal to the synchronous speed of the rotor. Hence, it is also known as an asynchronous motor.