What is torque speed characteristic of induction motor?
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What is torque speed characteristic of induction motor?
The torque-speed characteristics of a 3-phase induction motor is defined as the curve plotted between torque developed and rotational speed of the motor. It gives the information about variation in the motor torque with the change in its speed.
What are the characteristics of induction motor squirrel cage type?
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 is the torque of squirrel cage induction motor?
Starting Torque of Squirrel Cage Motors – For the squirrel cage motors, the starting torque is very low about 1.5 to 2 times of the full-load value. Starting Torque of Wound Rotor Motors – In case of slip ring induction motors, the resistance of the rotor circuit can be increased by inserting external resistance.
How is the speed of a squirrel cage induction motor determined?
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.
What are the characteristics of torque?
Torque is proportional to voltage squared and the current is proportional to the voltage. So, if the stator voltage is reduced the speed reduces and similarly if the stator voltage is increased the speed also increases.
What is the relation between torque and speed in induction motor?
The relation between torque and speed are inversely proportional to each other.
Why the starting torque of squirrel cage induction motor is low?
At start, the rotor reactance is large because slip of the motor at start is equal to unity. The large rotor reactance at start makes the starting torque of the motor poor. The motor draws about 5 to 6 times current of its full load current and produce very less torque.
Which of the following conditions is the squirrel cage induction motor?
Low starting torque. It cannot be used in cases where it requires considerable load torque. Starting current is about 6 to 3 times full-load current.
Why is the maximum torque of a squirrel cage induction motor called pull out torque?
The maximum torque of a squirrel cage induction motor is also called pull-out torque because of the way the motor reacts to an overload.
Why do squirrel cages have low starting torque?
The motor draws about 5 to 6 times the current of its full load current and produces very less torque. Most of the current is reactive in nature and does not contribute to the production of torque. That is why the starting torque of the squirrel cage induction motor is poor.
What is the speed of squirrel cage motor fixed?
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.
How is the speed of the squirrel cage induction motor controlled by inverter?
The pulses generated by the PIC microcontroller are given into the opto-coupler and we get a high level voltage pulses which is necessary for triggering the IGBTs in the three phase Inverter. Thus the speed of motor is controlled by varying the frequency of the output of inverter.
What is torque speed?
Torque relates to the rotational force of an electric motor while speed refers to the rate that the motor can rotate. This means that torque is associated with rotational force while speed relates to the rate of rotation which can be calculated by examining the RPMs, or revolutions per minute.
What are the three regions in the speed torque characteristics of the induction motor?
The torque-slip characteristic curve can be divided roughly into three regions: Low slip region. Medium slip region. High slip region.
What is the relationship between torque and speed?
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.
How do you increase the torque of a squirrel cage induction motor?
The starting torque of squirrel cage induction motor can be increased by using double squirrel cage rotor. In this case, rotor has two sets of independent cages. Upper cage has high resistance and low reactance while lower cage has low resistance and high reactance.
Which type of induction motor has high starting torque?
Capacitor-start motor
Capacitor-start motor: The capacitor-start motor develops a much higher starting torque, i.e. 3.0 to 4.5 times the full-load torque.To obtain a high starting torque, the value of the starting capacitor must be large, and the resistance of starting winding must be low.
What is speed control of induction motor?
Induction motor speed control is a process of manipulating currents in an induction motor to regulate speed. While often used in fixed frequency applications, induction motors are popular for variable frequency applications such as industrial drives and electric vehicles.
How do you find the speed at which maximum torque occurs in induction motor?
So, when slip s = R2 / X2, the torque will be maximum and this slip is called maximum slip Sm and it is defined as the ratio of rotor resistance to that of rotor reactance. NOTE: At starting S = 1, so the maximum starting torque occur when rotor resistance is equal to rotor reactance.
What conditions are needed for an induction motor to achieve maximum torque?
To develop maximum torque at the standstill condition, the rotor resistance must be high and should be equal to X20. But to develop a torque that is maximum at the running condition the rotor resistance must be low.
