The main construction of 3 phase induction motor is stator and rotor as what have been discussed below.
Stator frame, stator core, stator winding are the three basic construction of the three phase induction motor.
The outer part of the 3 phase induction motor is the stator frame, which to support the stator core and the field winding, to protect and supply mechanical power to those parts within the induction motor. It’s main component material is die cast or fabricated steel. And it must be strong and rigid enough to stay concentric with stator, to escape an unbalanced magnetic pull.
The stator core is to carry the alternating flux, for cutting the eddy current loss, it is laminated. These laminated types of structure’s main material is nearly 0.4 to 0.5 mm-thick stamping made up of silicon steel and is housed in stator frame to cut the hysteresis loss occurring in motor.
The stator windings, lain on the slots on the periphery of stator core of the three phase induction motor, is powered by three phase ac supply. Which one the three phases of the winding connecting in, star or delta, is according to the type starting method employed. And the stator of squirrel cage motor is connecting in delta for the squirrel cage motor is mostly started by star – delta stater. For the slip ring three phase induction motor are started by inserting resistances , the stator winding of slip ring induction motor connected either in star or delta is effective. The winding wound, also named field winding, which is on the stator of 3 phase induction motor, is to build a rotating magnetic field when this winding is excited by three phase ac supply.
The rotor is composed of a series of slotted steel laminations as a form of a cylindrical magnetic path and the electrical circuit. The electrical circuit of the rotor can be classified as:
Wound rotor type, involving 3 sets of insulated windings with connections carried out to 3 slip rings installed on the shaft. And the rotating part connects to the external through brushes onto the slip rings. As a result, this kind of motor is regarded as a slip ring motor.
Squirrel cage rotor type, involving a set of copper or aluminum bars mounted into the slots, are connected to an end-ring at each end of the rotor. It is named for its construction, which is liken best to a ‘squirrel cage’. Aluminum rotor bars are usually die-cast into the rotor slots, which contributes to a very rugged construction. Even though the aluminum rotor bars are directly connected to the steel laminations, in fact that all the rotor current flows through the aluminum bars and not in the laminations.
1. Electrical engineering
2. Electrical 4U.com
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