Speed Control of Induction Motor – AC Motor Speed Control Methods. … By changing the supply voltage of the motor. Changing the stator pole numbers of the motor. Changing the frequency of the supply side of the motor.
How can the speed of an induction motor be reduced?
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.
How do you control the RPM of an electric motor?
AC motors are constant speed devices but their speed can vary if you change the input voltage or frequency or the windings that make the motor rotate. The most common and efficient way of changing the speed is to vary the frequency by using an inverter as the power supply.
What causes the current to decrease as an induction motor accelerates?
What causes current to decrease as an induction motor accelerates? … Therefore the effective rotor resistance in the circuit is 50 times that of when the motor was starting. The whole rotor impedance or the motor impedance as a whole is therefore much higher at running speed and therefore the current is lower.
How can you control the speed of a motor?
Speed Control by Variation of Supply Voltage:
This is a slip-control method with constant frequency variable supply voltage. In this method of speed control of induction motors, the voltage applied to the stator is varied for varying the speed.
How can you reduce the rpm of a motor with a pulley?
By changing the diameter of the pulley wheels, speed can be changed. A smaller pulley turning a larger pulley results in the larger one moving more slowly but with more shaft power.
How can we increase the rpm of dc motor?
Increasing the speed can be achieved by increasing the supply frequency as the speed and frequency are directly proportional; however, there are two constraints. The first is the saturation of the magnetic circuit, but this issue can be significantly avoided by keeping the V/f ratio constant.
How do you reduce the rpm of a single phase AC motor?
The two primary ways to control the speed of a single-phase AC motor is to either change the frequency of the line voltage the motor sees or by changing the voltage seen by the motor, thereby changing the rotational speed of the motor.
Why do we use induction motor?
Slip ring motors require external resistors to have high starting torque. Induction motors are used in industry and domestic appliances because these are rugged in construction requiring hardly any maintenance, that they are comparatively cheap, and require supply only to the stator.
What is the base speed of induction motor?
The typical base speed of the four pole induction motor varies between 1420 and 1480 RPM at 50 Hz, while the synchronous speed is 1500 RPM at 50 Hz.
Which starting method is the best method in induction motor?
Starting of an Induction Motor
- Direct on line starter. The direct on line starter method, of an induction motor is simple and economical. …
- Star delta starter. The star delta starter method of starting three phase induction motors is very common and widely used among all the methods. …
- Auto transformer starter.
How do you slow down an AC motor?
If it’s a small fan motor or even a ceiling fan, this is often done by reducing voltage to the motor with a solid state control or a series inductance. This just increases the slip speed. A large AC motor can be slowed down with a Variable Frequency Drive.