How to Determine Speed of a Squirrel Cage Induction Motor 
Before you get started on designing your next electric motor, you will need to know how to determine the speed of a squirrel cage induction motor. There are many factors to consider, including rotor speed, Starting torque, and Rated torque. The following guide will help you determine the right speed for your specific application. Use the table below to calculate the speed of your squirrel cage induction motor. Also, remember that squirrel cage induction motors are asynchronous, which means that the rotor will not spin at the same frequency as the AC current. The difference between AC frequency and shaft rotation is what creates motion.
Table of Contents
Calculation of rotor speed
In a squirrel cage induction motor, the rotor turns when the rotor is placed inside the rotating magnetic field. Without a rotor, the rotor will not turn, because the stator windings lack sufficient inductance to generate power. Thus, they will burn if the current is too high. The calculation of rotor speed of a squirrel cage induction motor is crucial to its proper operation.
To determine the rotor speed of a squirrel cage induction motor, you need to know the synchronous and asynchronous speeds of the rotor. When the rotor is turned at a lower speed than the stator field, the rotor loses energy and does not create torque. The rotor turns at a slightly less speed than the synchronous speed of the stator field, thus minimizing the amount of energy lost by the squirrel cage.
The synchronous speed of the rotor of a squirrel cage induction motor is 1,200 RPM. Its stator winding contains six poles and is connected to a three-phase, 60-hertz source. The revolving field of the motor is at a synchronous speed of 1,200 RPM. As the speed of the squirrel cage induction motor increases, so does the synchronous speed.
Starting torque
If you’re wondering why a squirrel cage induction motor has low starting torque, you’re not alone. Induction motors in general exhibit low starting torque for two reasons. The first is that a squirrel cage induction motor’s rotor reactance is high, which is the opposite of what you’d want. If the slip of the rotor at start equals unity, the rotor reactance is high.
Putting a resistance between the rotor windings and the stator shunt will decrease the starting current and raise the starting torque. The resistance will also increase the breakdown torque peak, which shifts to the left of the rotor’s axis. This makes the starting torque peak much greater than what would be available without the resistance. The high resistance, coupled with a relatively low starting torque, will reduce the efficiency of the motor during normal operation.
To achieve a high starting torque, a squirrel cage induction motor should have a rotor of approximately 450 rpm. A squirrel cage induction motor has a rotor that is made of steel laminations with aluminum or copper conductors embedded in the surface. The stator contains a winding of wire carrying AC, which changes in sync with the sinusoidal alternation of the current. As this current changes, the generated electromagnetic field follows. The rotor then encounters a magnetic field that pushes it around.
Rated torque
Squirrel-cage induction motors, or asynchronous motors, convert electrical energy to mechanical energy. They are used in several industrial processes and are known for their inherent robustness and low maintenance requirements. The imposed torque by an electric motor is an essential diagnostic tool, revealing any failures and potential maintenance downtime. Measurements of torque can also be used to improve dynamic performance, reduce costs associated with unscheduled shutdowns, and maximize energy conversion efficiency.
A squirrel cage induction motor’s revolving portion consists of steel laminations or punchings in a cylindrical core. These are connected to copper end rings, which are tapped into the frame. The rotor shaft is supported by ball or sleeve bearings. This cutaway view of an assembled motor reveals the motor’s basic parts. Listed below are its major parts:
A squirrel cage induction motor consists of a silicon steel core that does not have copper windings. It also has bars running along its length, much like a squirrel’s cage. Current is induced in the rotor bars by the rotating magnetic field from the stator. Current flows through these bars and ends in a spiral fashion, creating torque. However, it must be noted that the rotor will always rotate at a slightly slower rate than the stator.
What is the difference between a squirrel cage induction motor and a squirrel cage asynchronous motor?
The main difference between a squirrel cage induction motor and a squirrel cage asynchronous motor is that the induction motor has a higher starting torque than the asynchronous motor.
How do you determine the speed of a squirrel cage induction motor?
The speed of a squirrel cage induction motor can be determined by using a tachometer measuring the frequency of the voltage applied to the motor or by using a stroboscope.
What is the difference between a squirrel cage induction motor and a wound rotor induction motor?
The main difference between a squirrel cage induction motor and a wound rotor induction motor is that the squirrel cage induction motor has a simpler construction and is less expensive than the wound rotor induction motor.
What are the advantages of a squirrel cage induction motor?
Some advantages of a squirrel cage induction motor include that they are rugged and have a simple construction which leads to a lower cost.
They also have a high starting torque and are not as affected by voltage fluctuations as other types of motors.
What are the disadvantages of a squirrel cage induction motor?
Some disadvantages of a squirrel cage induction motor include that they require more power to start than other types of motors and they are not as efficient as other types of motors at higher speeds.
What is the slip of a squirrel cage induction motor?
The slip of a squirrel cage induction motor is the difference between the synchronous speed and the actual speed of the motor.
What causes the slip of a squirrel cage induction motor?
The slip of a squirrel cage induction motor is caused by the rotating magnetic field of the stator.
What is the rotor speed of a squirrel cage induction motor?
The rotor speed of a squirrel cage induction motor is the actual speed of the motor.
What is the synchronous speed of a squirrel cage induction motor?
The synchronous speed of a squirrel cage induction motor is the speed at which the rotating magnetic field of the stator rotates.
How does the slip of a squirrel cage induction motor affect the speed of the motor?
The slip of a squirrel cage induction motor affects the speed of the motor by reducing the speed of the rotor.
How does the slip of a squirrel cage induction motor affect the torque of the motor?
The slip of a squirrel cage induction motor affects the torque of the motor by reducing the starting torque.
How does the slip of a squirrel cage induction motor affect the power factor of the motor?
The slip of a squirrel cage induction motor affects the power factor of the motor by reducing the power factor at low speeds.
How does the slip of a squirrel cage induction motor affect the efficiency of the motor?
The slip of a squirrel cage induction motor affects the efficiency of the motor by reducing the efficiency at low speeds.
What is the light load speed of a squirrel cage induction motor?
The light load speed of a squirrel cage induction motor is the speed at which the motor produces its rated torque at its rated power factor.
What is the no load speed of a squirrel cage induction motor?
The no load speed of a squirrel cage induction motor is the speed at which the motor produces no torque at its rated power factor.
Jessica Watson is a PHD holder from the University of Washington. She studied behavior and interaction between squirrels and has presented her research in several wildlife conferences including TWS Annual Conference in Winnipeg.
