Table of Contents
An electric motor converts electrical power to mechanical power in its rotor (rotating part). An induction motor is sometimes called a rotating transformer because the stator (stationary part) is essentially the primary side of the transformer and the rotor (rotating part) is the secondary side.
Can induction motor be used as transformer?
An induction motor is a well-known device which works on the principle of transformer. That is, when an EMF is supplied to its stator, then as a result of electromagnetic induction, a voltage is induced in its rotor. So an induction motor is said to be a transformer with rotating secondary.
Why is transformer used in induction motor?
Since the rotor is short-circuited there will be a circulation of currents in the rotor, thereby transferring the energy by mutual induction. This is the main reason for an induction motor to be referred to as a transformer.
Why does induction motor rotate but not a three phase transformer while subjected to identical 3 ø AC supply explain?
An induction motor has these two and hence it rotates. But in transformer, it has only time phase vector and it does not rotate. Because motor have permanent poles which make it to rotate and transformer dont have such permanent electromagnetic pole arrangement.
Is it necessary to have slip S 0 when we run induction motor?
When the Value of Slip is ‘0’ Therefore, emf will not be generated within rotor coils for generating rotor current. So this motor will not work. So, it essential to have a positive slip value in this motor and due to this reason, the slip will never become ‘0’ in an induction motor.
Is transformer a motor?
A transformer is an alternating flux machine while induction motor is a rotating flux machine. In a transformer, mostly a ferromagnetic iron core is used as a medium for the passage of flux from primary to secondary, whereas in an induction motor, the air gap is used between rotor and stator.
What is the working principle of induction motor?
Working Principle of Induction Motor The motor which works on the principle of electromagnetic induction is known as the induction motor. The electromagnetic induction is the phenomenon in which the electromotive force induces across the electrical conductor when it is placed in a rotating magnetic field.
What is the difference between synchronous motor and induction motor?
Synchronous motors require an additional DC power source for energizing rotor winding. Induction motors do not require any additional power source. Synchronous motors require additional starting mechanism to initially rotate the rotor near to the synchronous speed. No starting mechanism is required in induction motors.
What are types of induction motor?
Types of Induction Motors Split Phase Induction Motor. Capacitor Start Induction Motor. Capacitor Start and Capacitor Run Induction Motor. Shaded Pole Induction Motor.
What is the efficiency of induction motor?
Efficiency of three-phase induction motors can vary from 85% to 96%. See the chart below for torque vs. slip. Induction motors of 50-100 HP for industrial applications vary in weight from 700 to almost 1,000 lbs.
What would happen if a transformer is connected to a DC supply?
If the primary of a transformer is connected to the DC supply, the primary will draw a steady current and hence produce a constant flux. Consequently, no back EMF will be produced. Care must be taken not to the connect the primary of a transformer across the DC Supply.
What happens if an induction motor runs below its rated voltage?
Low voltage can lead to overheating, shortened life, reduced starting ability, and reduced pull-up and pullout torque. The starting torque, pull-up torque, and pullout torque of induction motors all change, based on the applied voltage squared.
Why do we use compensating winding in AC motor?
Compensating winding in AC series motor is used to reduce sparking of brushes. Important Point: In a DC machine, two kinds of magnetic fluxes are present (armature flux and main field flux). The effect of armature flux on the main field flux is called as armature reaction.
When can only slip of an induction motor is zero?
Zero slip means that rotor speed is equal to synchronous speed. If rotor is rotating at synchronous speed in the direction of rotating magnetic field the, there will be no flux cutting action, no emf in the rotor conductors, no current in rotor bar conductor and hence no development of electromagnetic torque.
What are the operating modes of 3 φ induction motor?
There are three known operating modes: breaking mode for slip values between ∞ and 1, motor mode for slip values between 1 and 0, and generator mode for slip values between 0 and −∞ . All three operating modes are as part of torque characteristic shown in Figure 1.
What is the normal slip of an 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.
What are the losses in transformer?
A transformer’s output power is always slightly less than the transformer’s input power. These power losses end up as heat that must be removed from the transformer. The four main types of loss are resistive loss, eddy currents, hysteresis, and flux loss.
What is the fundamental driving force of motors?
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor’s magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor’s shaft.
What is the emf equation of a transformer?
Therefore, RMS value of emf per turn = 1.11 x 4f Φm = 4.44f Φm. This is called the emf equation of transformer, which shows, emf / number of turns is same for both primary and secondary winding. For an ideal transformer on no load, E1 = V1 and E2 = V2 .
What are the starting methods of induction motor?
Methods of Starting Three Phase Induction Motors. Direct-on-Line Starter (DOL) Star Delta starter. Auto-Transformer Starting. Rotor Resistance Starter. Review.
What are the parameters of induction motor?
The motor parameters to be estimated are: stator and rotor resistances (R1 and R2), stator and rotor leakage inductances (lσ1 and lσ2), magnetizing inductance (LH), moment of inertia (J) and friction coefficient (KD). For this, we developed a function approximator algorithm using a differential evolution technique.
