What is the advantage of the wound rotor motor over the squirrel cage motor?

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.

What is the difference between a squirrel cage motor and a wound rotor motor?

The phase wound motor consists external resistance circuit, whereas in squirrel cage motor it is not possible to add any external resistance circuit because their rotor bars are permanently slotted.

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.

What is the advantage of the wound rotor?

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.

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 are the advantages and disadvantages of a squirrel cage rotor over a wound rotor motor?

Squirrel Cage Induction Motors requires less conductor material than slip ring motor, hence copper losses in squirrel cage motors are less results in higher efficiency compared to slip ring induction motor.

Why it is called a squirrel cage rotor?

Internally it contains longitudinal conductive bars (usually made of aluminium or copper) set into grooves and connected at both ends by shorting rings forming a cage-like shape. The name is derived from the similarity between this rings-and-bars winding and a squirrel cage.

How does torque increase in squirrel cage induction motor?

There were many attempts to design the rotor bar shape to increase the starting torque in squirrel cage induction motor, and it is well known that deep slot of rotor bar increases the starting torque. However, this deep slot increases the leakage flux so that it hurts the running efficiencies.

Which motors has high starting torque?

The capacitor start motor develops a much higher starting torque of about 3 to 4.5 times of the full load torque.

What happens to the starting torque of a wound rotor motor when you increase the resistance in series with the rotor windings?

Answer: 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 are the effects of increasing rotor resistance on starting current and starting torque of wound field induction motor?

While high starting torques are desirable, high rotor resistance results in a relatively high slip during normal running operation. The high resistance causes increased losses and reduced efficiency during normal operation.