3 phase of induction motor 2015 16
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Transcript of 3 phase of induction motor 2015 16
ESHAN COLLEGE OF ENGINEERING FARAH, MATHURA
SEMINAR PRESENTATION
ON 3-PHASE INDUCTION MOTOR
Submitted to-: Submitted by-: Er.Mayank jain Pawan kumar B.Tech EE(3rd Year) Roll no.1347120006
Contents• Introduction• Construction• Parts of induction motor• Rotor construction• Rotating magnetic field(RMF)• Principle of operation• Equivalent circuit• Power losses• Power flow in induction motor• Torque speed characteristics• Speed control• Advantage• Application.
Introduction
• Induction Motors transform electrical energy into mechanical energy. – simple design, Cheap,robust, low-price, easy
maintenance.– wide range of power ratings: fraction
horsepower to 10 MW – run essentially as constant speed from no-load
to full load.– Its speed depends on the frequency of the
power source.
Construction
• The three basic parts of an Induction motor are the rotor, stator, and enclosure.
• The stator and the rotor are electrical circuits that perform as electromagnets.
Parts of induction motor
Rotor construction
• The rotor is the rotating part of the electromagnetic circuit.
• It can be found in two types:– Squirrel cage–Wound rotor
• However, the most common type of rotor is the “squirrel cage” rotor.
Fig.1.Squirrel cage rotor Fig.2.Wound rotor
Rotating magnetic field
• When a 3 phase stator winding is connected to a 3 phase voltage supply, 3 phase current will flow in the windings, which also will induced 3 phase flux in the stator.
• These flux will rotate at a speed called a synchronous speed, ns. The flux is called as rotating magnetic field
• Synchronous speed: speed of rotating flux
pfns
120
Principle of operation
• When a 3 phase stator winding is connected to a 3 phase voltage supply, 3 phase current will flow in the windings, hence the stator is energized.
• A rotating flux φ is produced in the air gap. The flux Φ induces a voltage ea in the rotor winding (like a transformer).
• The induced voltage produces rotor current, if rotor circuit is closed.
• The rotor current interacts with the flux φ, producing torque. The rotor rotates in the direction of the rotating flux.
Equivalent Circuit
Power losses
• Copper losses– Copper loss in the stator (PSCL) = I12R1– Copper loss in the rotor (PRCL) = I22R2
• Core loss (Pcore)• Mechanical power loss due to friction and wind age.
Power flow in induction motor
Torque-speed characteristics
Speed Control
There are 3 types of speed control of 3 phase induction machines
i. Varying rotor resistance.ii. Varying supply Frequency.iii. Stator voltage control.
Advantage
• Low cost.• High starting torque.• Maintenance easily.• Induction motor can be operated in polluted and
explosive environments.• Induction motor are simple and robust in construction.
Application
• Water pump.• Lathe machine• Printing machine• Grinding machine.
QUERIES ????