8/10/2019 ELE 351L lab 3

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ELE 351L

Electrical Energy Conversion

Section 1

LAB INSTRUCTOR:Kashif Bangash

Lab report 3

Single Phase Transformer Modeling

Muhammad Shafiq Asad - 37907

Asad Ur Rehman Muhammad-41798

Sheehan Fernandes-49935

Sohail Nouraei -48489

Submitted on: 11/11/2014

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Abstract

This lab is going to be about single phase transformer modeling. First of all, in this lab

we were required to learn how to appropriately model single phase transformers and

transformer banks. Secondly, we were going to carry out transformer open circuit and

short circuit tests. Lastly, we had to study the transformer regulation and efficiency with

varying loads. The important equations needed to understand before performing the

experiments were:

Open circuit test

short circuit test

a

SNpN

(t)sV

(t)pV

(t)si*sN(t)pi*pN

cX1j

cR1Y

E

ocVocI

YE

ocIocVocPcosp.f

ocVocIY

E

scIscVZ

SE

scIscVscPcosp.f

eq

jX

eq

R

scI

scVZSE

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Table of Contents

Section Page Number

Abstract 2

Procedure 4

Conclusion 11

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Procedure

Open Circuit Test

Figure 1

Table 1

Short Circuit Test

Figure 2

Quantity Value

V 400 V

I 0.05 A

P 0 W

Watt meter

A

Watt meter

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Note:- All below values are of primary side not secondary side of transformer

Quantity Value Units

V 60 V

I 1.5 A

P 85 W

Table 2

Q1) With the information above from Table 1 & 2 compute the equivalent circuit of the

transformer of the form provided

|YE| = IOC/VOC= 0.05 / 400 = 0.000125

= cos-1

( POC / IOC VOC) = cos-1

( 0 / ( 400 x 0.05) = cos-1

( 0 )

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= 90

YE = 0.00012590 = 0 + 0.000125j

GC= 0 and BM = 0.000125

RC = 1 / GC =

RC =

XM = 1/ BM

XM = 8000j

|ZSC| = VSC / ISC= 60/1.5 = 40

= cos-1

( PSC / ISC VSC) = cos-1

( 85 / ( 60 x 1.5) = 19.19

ZSC = 40 19.19 = 37.78 + 13.15j

Req= 37.78

Xeq= 13.15j

Question 3:

Open Circuit Test

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Quantity Value

V 400 V

I 0.05 A

P 0 W

Short Circuit Test

Quantity Value Units

V 100 V

I 2.6 A

P 140 W

Q2) With the information above from steps 1 & 3 compute the equivalent circuit of the

transformer of the form provided.

|YE| = IOC/VOC= 0.05 / 400 = 0.000125

= cos-1

( POC / IOC VOC) = cos-1

( 0 / ( 400 x 0.05) = cos-1

( 0 )

= 90

YE = 0.00012590 = 0 + 0.000125j

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GC= 0 and BM = 0.000125

RC = 1 / GC =

RC =

XM = 8000j

|ZSC| = VSC / ISC= 100/2.6 = 38.46

= cos-1

( PSC / ISC VSC) = cos-1

( 1400 / ( 100 x 2.6) = 57.42

ZSC = 38.46 57.42 = 20.71 + 32.41j

Req= 20.71

Xeq= 32.41j

1. Connect voltmeter to the secondary side of the same transformer used in step 1 and

adjust the input voltage at the primary side to 400 V(line to line voltage) then measure

the no load voltage(no load voltage mean connect voltmeter to the secondary side of

transformer when no load is connected to the secondary side of transformer)

Vnl = 400 V

Voltage regulation: Compares the output voltage of the transformer at no load with the output

voltage at full load

100%

fls,V

fls,V

nls,V

VR

100%

fls,V

fls,V/pV

VR

a

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The transformer efficiency can be computed by:

= (PinCore lossCopper loss)/Pin

2.

Connect resistive load (R = 685.7 ) to the secondary side of the transformer in step 4

and two Watt meter one to the primary side and another one to the secondary side

(figure 3). Then record your measurements of Vfl, Pinand Poutin the following table. Also

compute the voltage regulation and the efficiency of the transformer.

Vfl Pin Pout VR

370 V 210 W 190 W 8.11 % 9.52 %

Table 5

3. Repeat step 5 but use inductive load(XL=j 685.7 ) at the secondary side

Vfl Pin Pout VR

395 V 70 W 40 W 1.27 % 42.9 %

Table 6

4. Repeat step 5 but use capacitive load(XL= -j 685.7 ) at the secondary side

Vfl Pin Pout VR

405 V 10 W -5 W 1.23 % 50 %

Table 7

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5. Repeat step 5 but connect load of ( 685.7 + j 685.7 )

Vfl Pin Pout VR

380 V 120 W 110 W 5.26 % 8.33%

Table 8

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Conclusion

The purpose of this experiment was to familiarize us with the concept of open circuit

and short circuit tests and how to carry them out. First, we measured the values of voltage,

current and power using open circuit and short circuit test. Then, we used the values obtained

from the tests to calculate the equivalent circuit of the given transformer.

The second part of this experiment was aimed to increase our understating of the

concept of voltage regulation and efficiency as well as the reactions different types of loads

have on the output power. Finally, we connected different types of loads to our system

(resistive, capacitive, inductive and mixed) and measured the change in the circuit's voltage

regulation and efficiency. We saw that the voltage regulation is at its highest when we use a

purely resistive load and the efficiency is at its highest when the load is purely capacitive.