motor project buet

8/13/2019 Motor Project BUET

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BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY

DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING

Course No: EEE 208

Course Title: Energy Conversion Laboratory

Project Title: Re-wiring Stator Winding of a 3-Phase Induction Motor

Submitted to:

(1)

Dr. Shahidul Islam Khan

Professor

EEE, BUET

(2)

Hamidur Rahman

Associate Professor

EEE, BUET

Submitted By:

Name Student I.D.

Md. Redwan Islam 1006066

Md. Rayhan Khan 1006067

Abdullah Abu Sayed 1006068

Arifuzzaman Faisal 1006069

Kamruzzaman Nahid 1006070

Mohammad Tariqul Islam 1006071

Md. Khalid Mahmud 1006072


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Objective:

1. To study the structure of a three phase induction motor.

2. To re-wire the stator winding of a squirrel cage induction motor.

Description of the Motor:

A motor with following nameplate is bought:

TEECO 3PHASE INDUCTION MOTORTYPE MS 712-4 IP 44

0.5 HP 0.37 KW 440 V

Y 0.97A 1400 rpm

INS. OL. B 50 Hz S1

STANDARD JB/T 1009-2007 NO.

TEECO STANDARD MOTORS LTD.

Discussion about the Stator Winding:

The stator winding is observed and the following data is obtained:

Type of Wire 26 Gauge (0.405 mm diameter)

Stator Type Semi-closed Slot Stator

No. of Slots 24

Connection Type 4 pole Y - Connected

No. of Layers 1

Wires in each Slot 165

From the nameplate, this is a Design Class B motor. So, expected maximum torque is

moderately high.

The stator winding follows the following diagram:


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The YConnected Stator is shown in above figure. The phases follow the following pattern:

Phase No. Winding Direction Color in the figure

a Phase 01-06-12-07-13-18-24-19 Red

b Phase 05-10-16-11-17-22-04-23 Blue

c Phase 09-14-20-15-21-02-08-03 Green

The terminals 19, 23 and 03 are shorted. And terminals 01, 05 and 09 are the 3 phase voltage

input.

Procedure:

1. The motor is dismantled under the supervision of Lab Assistant Mr. Debashish. The

following picture is taken:


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2. Then the motors stator winding is completely removed.The following is a picture of

stator after the wires has been removed:

And the following picture is of wire:


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3. Then the winding was done again with the wire of same diameter:

4. After this the motor parts have been re-assembled.

Tests:

Weight of Removed Stator Winding:

980 grams.


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DC Test:

Parameters Value

RDC 49.4

No Load Test:

Parameter Value

Vnl 400V

Inl 0.9A

Pnl(1 Phase) 42W

Locked-Rotor Test:

Parameter Value

Vlr 90V

Ilr 0.97A

Plr(1 Phase) 31W

Motor Parameter Calculation:

From DC Test:

R1= RDC/2 = 49.4/2 = 24.6

From No Load Test:

V,nl= 230.94V

Znl= V,nl/ Inl= 256.6

Now,

R12+ (X1+XM)

2= Znl2

from this expression,

X1+XM = 251.8

From Locked Rotor Test:

Note: Locked Rotor test was done in 50Hz (line frequency)

V,lr=51.96V

Zlr=V,lr/Ilr=53.57

lr=cos-1(P/(V,lrIlr)) = 52.04

Now,R1+R2= Zlrcos(lr) = 32.95


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Xlr=X1+X2= Zlrsin(lr) = 42.23

Now,

R2=32.95-R1=8.35

Since it is a design B motor,X1=0.4Xlr=16.869

X2=0.6Xlr=25.338

XM=251.8X1=234.931

So, the data obtained are:

Parameter Value

R1 24.6

R2 8.35X1 16.869

X2 25.338

XM 234.931

Discussion:

While re-wiring we phased some complications. These are listed below and it is also

explained how the complications were dealt with:

1. The lamination in the stator was damaged in the process of removing old stator coils. As aresult the stator needed re-lamination.

2. While removing the old winding and re-wiring, we accidentally displaced some of the

walls of stator slots. This created a problem while we tried to install the rotor after re-wiring.

Since the air gap is too small, a small displacement resulted in the rotor being stuck. This

problem was removed by hammering in the places which were displaced. The displacements

were removed as much as possible.

3. The wooden mount required for shaping the coils was acquired from a machine shop. But,

while using the mount, some of the wires got tangled and resulted in larger diameter coil thannecessary. As a result the coils didnt fit in the slots. These coils had to be prepared for the

second time.

4. Due to the Semi-Closed Slot, the coils could not be inserted directly into the stator, rather

special mechanism was required. Feeders or Insulating Papers were inserted into the stator so

that the lamination of stator and insulation of wires dont get damaged. Since it is a single

layer winding the complications were limited.

5. After the wiring is done, lamination coating was again applied on the wires.

6. The values obtained in Blocked Rotor Test are not completely correct. As, the frequency of

text was 50Hz, the obtained value is highly erroneous.

motor project buet

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