Which motor has this speed torque characteristics?
Torque Speed Characteristic of an Induction Motor The greater, the value of the R2, the greater is the value of the slip at which maximum torque occurs. As the rotor resistance increases, the pullout speed of the motor decreases. In this condition, the maximum torque remains constant.
How is the speed of a squirrel cage induction motor determined?
Squirrel-cage induction motor. When the three stator windings are fed by a three-phase alternating current (AC) supply, a rotating magnetic field is generated, the rotating speed of which is determined by the frequency of the power supply and by the number of magnetic poles of the motor.
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.
What is torque-speed?
Torque is the rotational equivalence of linear force. Speed measures the distance covered in unit time. The relation between torque and speed are inversely proportional to each other. The torque of a rotating object can be mathematically written as the ratio of power and angular velocity.
What are the characteristics of induction motor?
Because of this speed difference, the motor rotates at a speed slightly slower than the synchronous speed. Slip is normally expressed in percentage. Slip of a power induction motor is 2 to 3% when the motor is operated under the rated load. The above value becomes somewhat larger with small single-phase motors.
What are the characteristics of squirrel cage induction motors?
Some advantages of squirrel cage induction motors are:
- 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)
What three factors determine the amount of torque produced by a squirrel cage motor?
1. The strength of the magnetic field of the stator. 3. The speed of the cutting action.
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 can we increase the speed of induction motor?
Speed Control of Three Phase Induction Motor
- V / f control or frequency control.
- Changing the number of stator poles.
- Controlling supply voltage.
- Adding rheostat in the stator circuit.
What is the speed of a squirrel cage motor?
The most popular squirrel cage induction motor is of a 4-pole design. Its synchronous speed with a 50 Hz supply is therefore 60 f/p, or 1500 rpm. For a full-load operating slip of 3 per cent, the speed will then be (1 – s)60 f/p, or 1455 rpm. A disadvantage of the squirrel cage machine is its fixed rotor characteristic.
Why are induction motors called squirrel cage motors?
The reason behind the name “squirrel cage” is because of the type of rotor used in these motors. In these type of motors, the rotor is simplest and most rugged in construction. These motors have much higher efficiency than slip ring induction motors.
How is the speed of an induction motor dependent?
The speed of the induction motor is always dependent upon the load, the speed is going to decrease with the increase in load. The speed of the synchronous motor is not dependent on the load thus it remains constant at any load. In squirrel cage I.M cage, Squirrel cage rotor is used.
What are the characteristics of a squirrel cage?
The curves in Fig. 3 indicate squirrel cage motor characteristics. In the general case, the higher the starting torque the greater the full load slip. This is one of the important parameters of squirrel cage design as it influences the operating efficiency.