Separation of Losses in Induction Motor

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Expt. No. Date: Computation of Loss Components of an Asynchronous Motor OBJECTIVE To determine the iron loss and constant losses at no load in three phase induction motor.

APPARATUS REQUIRED

Sl. No. 1 2 3 4 5 6

Apparatus Ammeter Voltmeter Wattmeter Tachometer Auto Transformer T.P.S.T. switch

Type

Range

Quantity

FORMULAE USED: 1. Input Power = W1 +W2 2. Copper Loss = 3 Iph2 Rac 3. Rac = 1.06 R, Where R is the Stator Resistance

CIRCUIT DIAGRAM 3 - Φ Auto Transformer
R FUSE 415 V 50 Hz 3-Φ AC Y 415 V 50 Hz 3-Φ AC

3- Φ Induction Motor

A

M C

L V

R

Rotor

V
T P S FUSE T S
C M L V

B Y

B FUSE

THEORY The energy conversion process is carried out with the help of magnetic fields. These conversion processes also result in losses to the machine. Types of Losses The losses in a three phase induction machine are broadly classified into the following types 1) Magnetic losses 2) Electrical Losses 3) Mechanical Losses Magnetic losses The presence of rotating magnetic field in the stator core results in the magnetic losses. Stator core is made up of silicon steel or iron stampings, these losses is also called as core losses.

Eddy Current Loss The core material, steel, apart from being a good conductor for the magnetic field is also a good conductor of electricity. A cording to Faraday's first law the flux reversals in the stator core cause an emf called the Eddy emf to be induced in the core. The amount of Eddy emf induced is proportional to the flux density and the frequency of flux reversal. This emf causes a current called Eddy Current through the body of the stator core causing Eddy current losses. Eddy Current Loss = Eddy current 2xResistance of the stator core. Electrical Losses Electrical Losses occur due to Ohmic resistances in the stator and the rotor windings which are made u p of copper. Hence electrical losses also, called as Copper losses. Since load current varies, the total copper losses varying square...
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