Why Induction Motor cannot run at Synchronous Speed?
Why Induction Motor cannot run at synchronous speed?
An
induction motor is designed to operate at a speed that is slightly less than
the synchronous speed of the motor. The synchronous speed of an induction motor
is determined by the frequency of the power supply and the number of poles in
the motor. The synchronous speed can be calculated using the formula:
Synchronous
Speed = (120 x Frequency) / Number of Poles
When an
induction motor is connected to a power supply and the rotor is at standstill,
the motor operates at a speed that is less than the synchronous speed. This is
because the rotor has to slip in order to create the necessary magnetic field
to induce the current in the rotor windings.
If the
rotor were to operate at synchronous speed, there would be no relative motion
between the magnetic field of the stator and the rotor, and therefore no
induced current in the rotor. As a result, there would be no torque generated,
and the motor would not be able to start or run.
In summary, an induction motor cannot run at synchronous speed because it requires relative motion between the magnetic field of the stator and the rotor to induce current in the rotor windings, and generate the necessary torque to start and run the motor.
What is Induction Motor?
An
induction motor is an electric motor that operates based on the principles of
electromagnetic induction. It is one of the most commonly used types of
electric motor, with applications in a wide range of industries including
manufacturing, transportation, and household appliances.
The basic
design of an induction motor consists of a stator (stationary part) and a rotor
(rotating part). The stator contains a series of windings that are supplied
with AC power from an external source. This AC power creates a magnetic field
in the stator windings, which rotates around the circumference of the stator.
The rotor
is a cylindrical iron core with conductive bars, also known as "squirrel
cages," mounted on its surface. When the stator magnetic field rotates, it
induces an electromotive force (EMF) in the rotor bars, which in turn creates a
magnetic field in the rotor. This interaction between the stator and rotor
magnetic fields generates torque, causing the rotor to spin and ultimately
power the load.
Unlike
other types of electric motors, induction motors do not require brushes or
commutators to transfer power from the stator to the rotor, which makes them
simple, robust, and low-maintenance. Additionally, induction motors are highly
efficient and can be designed to operate at a wide range of speeds, depending
on the specific application requirements.
What is synchronous speed?
Synchronous
speed is the speed at which the magnetic field generated by the stator of an AC
electric motor rotates. It is determined by the frequency of the power supply
and the number of poles in the motor, and is a function of the physical
dimensions and design of the motor.
The
synchronous speed of an AC motor can be calculated using the following formula:
Synchronous
Speed = (120 x Frequency) / Number of Poles
where
"Frequency" is the frequency of the AC power supply in hertz, and
"Number of Poles" is the number of magnetic poles in the motor.
It is important to note that the actual operating speed of an AC motor is typically lower than the synchronous speed due to the presence of rotor slip, which is the difference between the synchronous speed and the actual operating speed of the rotor. The amount of slip is influenced by the load on the motor and varies with the specific motor design and operating conditions.
What is the slip of the Induction Motor?
The slip
of an induction motor is the difference between the synchronous speed of the
rotating magnetic field in the stator and the actual rotational speed of the
rotor. In other words, it is the amount of "slippage" that occurs
between the rotating magnetic field of the stator and the rotor, which is
necessary for the induction motor to generate torque and operate.
The slip
of an induction motor is expressed as a percentage, and can be calculated using
the following formula:
Slip (%) =
[(Synchronous Speed - Actual Rotor Speed) / Synchronous Speed] x 100
For
example, if the synchronous speed of an induction motor is 1800 RPM
(revolutions per minute), and the actual speed of the rotor is measured at 1750
RPM, the slip would be:
Slip (%) =
[(1800 - 1750) / 1800] x 100 = 2.78%
The amount
of slip in an induction motor is influenced by factors such as the motor's
design, the load on the motor, and the frequency of the power supply.
Typically, the higher the load on the motor, the greater the slip, which in
turn leads to a reduction in the motor's efficiency.
S ynchronous
speed of Induction Motor Formula
The
synchronous speed of an induction motor can be calculated using the following
formula:
Synchronous
Speed = (120 x Frequency) / Number of Poles
where:
- "Frequency" is the
frequency of the AC power supply in hertz (Hz)
- "Number of Poles" is
the number of magnetic poles in the motor
For
example, consider an induction motor with a power supply frequency of 60 Hz and
4 poles. Using the formula, we can calculate the synchronous speed as:
Synchronous
Speed = (120 x 60) / 4 = 1800 RPM
This means that in this example, the rotating magnetic field generated by the stator of the induction motor will rotate at a speed of 1800 revolutions per minute, assuming no load or slip on the motor. However, the actual operating speed of the rotor will be less than the synchronous speed due to the presence of slip.
what is
synchronous speed in induction motor
In an
induction motor, synchronous speed refers to the speed at which the rotating
magnetic field generated by the stator of the motor rotates. It is determined
by the frequency of the AC power supply and the number of magnetic poles in the
motor.
The
formula to calculate the synchronous speed of an induction motor is:
Synchronous
Speed = (120 x Frequency) / Number of Poles
where:
- "Frequency" is the
frequency of the AC power supply in hertz (Hz)
- "Number of Poles" is
the number of magnetic poles in the motor
For
example, if an induction motor is connected to a power supply with a frequency
of 60 Hz and has 4 poles, the synchronous speed can be calculated as:
Synchronous
Speed = (120 x 60) / 4 = 1800 RPM
This means that in this example, the rotating magnetic field generated by the stator of the induction motor will rotate at a speed of 1800 revolutions per minute. However, the actual operating speed of the rotor will be less than the synchronous speed due to the presence of slip.
Read More: What is Induction Motor? How many types of Induction Motor and what are they? Detailed Discussion about Induction Motor
