Construction of induction motorĪ cross-section of the Induction motor is shown below,Īn Induction Motor basically consists of two parts
The current-carrying windings produce the magnetic field or flux, three sets of flux produced due to power supply, resultant flux has a constant magnitude and its axis rotating in space without physically rotating the windingsįield or flux having constant amplitude but whose axis continuously rotating in a plane with a certain speed, so if the arrangement is made to rotate a permanent magnet, then the resulting field is a rotating magnetic field. In 3 phase Induction, a motor Rotating Magnetic Field (RMF) is produced by supplying currents to a set of stationery winding (or) stator with the help of a 3 phase power supply. Why Induction motors are called Asynchronous motors ?īecause their rotors never run with the synchronous speed Working principle of induction motorĪn induction motor works in the principle of electromagnetic induction, EMF (Electromotive force) is a phenomenon that is induced across the electrical conductor when it is placed in a rotating magnetic field. What is Induction Motor (or) Asynchronous motor?Ī Three-phase induction motor is a single excited AC machine.
In AC supply, single-phase and three-phase motors are available. If the Greek symbols for alpha beta delta do not appear here the symbol font needs to be installed for correct display of notation and formulae.There are various types of motors available as classified below The symbol font is used for some notation and formulae. The resistance of the stator winding is measured using a small direct current.
Synchronous speed ns full#
If an induction machine with its rotor locked is energised at a reduced voltage which causes rated current input, then the input power represents the sum of the full load copper loss and stray loss of the machine. If an induction machine with its rotor unloaded is energised at rated voltage, then the input power represents the sum of the iron loss and mechanical loss of the machine. In all cases the magnetizing current (at lagging power factor) is provided by the supply system.
The rated load torque T M for a rated output power P M is:įor an induction machine with N s stator turns and N r rotor turns running at slip s on a supply of voltage E s and frequency f s, the rotor induced voltage and frequency E r and f r are:įor a rotor current I r, the equivalent stator current I rs is: Using angular speed w instead of rotational speed n: The per-unit slip s of an induction machine of synchronous rotational speed n s running at rotational speed n m is:
The synchronous rotational speed n s and synchronous angular speed w s of a machine with p pole pairs running on a supply of frequency f s are: