What is a 3 Phase Induction Motor ?
What is a 3 Phase Induction Motor ?
Three phase induction motor definition
A three-phase induction motor is a self-starting motor that converts three-phase AC electrical energy into mechanical energy without the need for an additional starting mechanism.
Main component
Three-phase induction motor stator
The stator of a three-phase induction motor consists of a number of slots to build a three-phase winding circuit, which we connect to a three-phase AC power supply. We arrange the three-phase windings in the slots in such a way that they generate a rotating magnetic field when we turn on the three-phase AC power supply.
Three-phase induction motor rotor
The rotor of the three-phase induction motor has a cylindrical laminated iron core with parallel slots for carrying the conductors. These conductors, made of heavy copper or aluminum strips, are installed in each slot and connected at both ends by end rings. The slots are intentionally tilted, rather than parallel to the shaft, to minimize magnetic noise and prevent motor stalling.
The working principle of three-phase induction motor
The generation of a rotating magnetic field
The stator of the motor consists of overlapping windings with an electrical Angle offset of 120o. When we connect the primary windings or stator to a three-phase AC power supply, it establishes a rotating magnetic field, which rotates at a synchronous speed.
Magnetic field generation
The three-phase winding arrangement of the stator generates a rotating magnetic field, which is essential for the operation of the motor.
Inductive operation
When the rotor is conducted through the stator's magnetic field, it senses an electromotive force, generates a current and causes the rotor to rotate, following the principle of electromagnetic induction.
Slip importance
The speed difference (slip) between the stator magnetic field and the rotor is critical because it allows for the generation of torque and prevents the rotor from reaching synchronous speed.
Advantages of three-phase induction motor
Self-activation
Since there are no commutators and brushes that can cause sparks, there are fewer armature reactions and brushes
Strong construction
Economy
Easier to maintain
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