test report pre ing desh energy tr 01

8/3/2019 Test Report PRE ing DESH ENERGY TR 01

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ENERGYPACR

E N E R G Y P A C E N G I N E E R I N G L T D.

DEPARTMENT OF RESEARCH & DEVELOPMENT

REF : EELF/TR- DESH- 35 MVA

REV : 00

DA TE : 12 / 12 /2010

P R E - C O M M IS S IO N I N G T E S T R E P O R T

TRANSFORMER 01

Name of the Client : DESH ENERGYLTD.

Job Description : 35 MVA, 11/132 KV, 3-phase, 50Hz, Power Transformer

Preference Standard : BS-171, IEC-76

Test Performed by : Engr. Rashiduzzaman Bulbul (Asstt. Engr., XFR, Testing)Engr. Mamun Biswas (Asstt. Engr., XFR, R&D)

Reviewed By : Engr. Faruk Hannan Raju (Sr. Engr., R&D)

Testing Duration : 08/12/2010 - 09/12/2010

Date of Issue :

Remarks

Test results are in conformance with contractual requirements.

Prepared By Mamun Biswas

Checked By Faruk Hannan

Testing Engr. Rashiduzzaman

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C O N T E N T S

1 PHYSICAL INSPECTIONS

1.1 Inspection for Transformer condition on arrival at site

1.2 Inspection for Transformer Accessories

2. T E S T I T E M S

2.1 Magnetic Balance test2.2 Measurement of excitation current

2.3 Vector group test

2.4 Measurement of voltage ratio

2.5 Measurement of winding insulation resistance




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1.1 Inspection for Transformer Condition on arrival at site

1. Explanation and criteria

1.1. Check for Damage: check the state of damage if the Transformer was dropped accidentally,

or reinforcement o& piping were distorted.

1.2. Rust : when the painting is damaged or the metal parts are rusted, remove the rust with sand

paper and coat with the appropriate paint.

1.3. Bolts & Nuts: check weather the bolts & Nuts are loosened or not.

Note: for any serious damaged the matter should be immediately informed to Energypac

Engineering Ltd.

2. Checking Result

Check Item Date Results Remarks

External Damage 08/12/2010 None Good

Rust 08/12/2010 None Good

Bolts & Nuts 08/12/2010 Tightened Good

Oil leakage 08/12/2010 none Good

RESULT : Satisfactory_______




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1.2 Transformer Rating Sheet

Apparatus : 35 MVA, 11/132 kV Transformer

Voltage ratio : 11/132 kV

Number of Phase(s) : 3 (Three)

Rated Frequency : 50 Hz

Vector Group : YNd1

Type of Cooling : ONAN / ONAF

Tapping Range : + 10 % to 20 % in steps of 1.25 % provided onHV winding.

Type of Tap Changer : ON-Load Tap Changer

Winding Designation : HV LV

Terminal Notation : A B C N a b c

Rated Capacity in MVA

ONAF : 35

Connections : Star Delta

Rated Voltage (in kV) : 132 11Rated Current (in Ampere) :

ONAF : 153.1 1837

Insulation level (in kV)

HV Winding : LI 650 kV, AC 275 kV

HV-N Winding : LI 325 kV, AC 140 kV

LV W inding : LI 75 kV, AC 28 kV

LV Voltage : 11000 Volts in all Tap Positions.




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1.3 Visual check of accessories

Name of accessories Result Date

High voltage line bushing (A Phase) GOOD 08/12/2010

High voltage line bushing (B Phase) GOOD 08/12/2010

High voltage line bushing (C Phase) GOOD 08/12/2010

Neutral bushing GOOD 08/12/2010

Low voltage bushing (a phase) GOOD 08/12/2010

Low voltage bushing (b phase) GOOD 08/12/2010

Low voltage bushing (c phase) GOOD 08/12/2010Radiators GOOD 08/12/2010

Conservator GOOD 08/12/2010

Cooling fan GOOD 08/12/2010

Valves GOOD 08/12/2010

Oil level indicator for OLTC GOOD 08/12/2010

Buchholz relay GOOD 08/12/2010

Dehydrating breather GOOD 08/12/2010




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TEST ITEMS

2.1 Magnetic Balance Test

PROCEDURE:

The following procedures are followed during magnetic balance check:1) Single phase supply (220v) is applied across one phase.

2) Voltage is measured from the other two phase.

For A-phase, when single phase voltage is applied in A-phase, flux A is produced. A will induce flux

B and C phase and for this,voltage will be generated at B & C phase.

A c

So,

A =B + C.OR, NIA/RA =NIB/RB +NIC/RC

As Rc > RB , c < B.




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So voltage induced in the C phase must be less than the voltage induced in phase B.

That is, VBN > VCN. Criteria 1.

For a balance 3 phase circuit,

VAN + VBN + VCN = 0

VAN = -( VBN + VCN)criteria 2.

So the sum of the voltage induced on the two phases should be almost equal to the applied voltage on the

3rd phase.

PHASE C:

THE SAME RESULT WILL BE OBTAINED WHILE APPLYING VOLTAGE IN THE C-

PHASE.

For C-phase,

VcN= -( VBN + VAN).

PHASE B:

FOR B-phase, as B is the middle phase, the flux induced by B, will be equally divided and A &

C phase will be induced equally. So,

B =C + A.OR, NIB/RB =NIC/RC +NIA/RA

Accordingly, VBN= -( VCN + VAN).

The above theory is verified in the test results given on the next page.




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MAGNETIC BALANCE (TEST DATA) :

a) Input Voltage in = 234 V

Voltage across < N-B > = 182 V

Voltage across < N-C > = 52 V

b) Input Voltage in < N - B > = 234 VVoltage across < N-A > = 62 V

Voltage across < N-C > = 175 V

c) Input Voltage in < N - C > = 238 VVoltage across < N-A > = 18 V

Voltage across < N-B > = 221 V

From the test data, the magnetic circuit is confirmed as a balanced circuit.

Result: ___________Magnetic circuit is well balanced_________

** Voltage measured by FLUKE-189Digital Meter, manufactured by FLUKE,USA.

** Current measured by KYORITSU-2431 milli amps Meter, by kyoritsu, japan.




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2.2 Measurement of Excitation current

3-phase Supply from HV side

Measured Voltage A-B : 407 V, Measured current : IA = 5.6 mA

Measured Voltage B-C : 409 V, Measured current : IB = 2.4 mA

Measured Voltage C-A : 409 V, Measured current : IC = 4.03 mA

Result: Excitation current is on normal magnitude & Balanced

** Voltage measured by FLUKE-189Digital Meter, manufactured by FLUKE,USA

** Current measured by KYORITSU-2431 milli amps Meter, by kyoritsu, japan.




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2.3 Vector Group Test

PROCEDURE:

There are few method of testing of vector group of a particular powerType equation

here.transformer. Among those one is to assume a vector group first and then perform the test

accordingly. If the test result matches the assumption then the vector group is proved. If it doesnt then a

new assumption is made.

The vector group of 30/35-11 transformer is found as YNd1 in the name plate. So we

assume that the vector group is YNd1 and then perform the following test.

Step 1: 3 phase supply is applied on the HT side.

A

a

c

C b B

Step 2: C and c is shorted. Then the vector diagram turns into the following:

A

a

c,C B

b

Vectorially. Voltage of Aa=Bb=Ba

And Ab is greater than all other voltage.

So. Ab> Aa=Ba=Bb..(1)

Step 3: measurement is performed to record the magnitude of Ab,Aa,Ba,Bb, comparison is done

according to 1.

The above procedures are followed below:




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TEST DATA:

Terminals Cand c shorted together.

Voltage applied across the terminals A-B- C = 410V, AC

Voltage measured across : Terminal A b = 414 V

TerminalA a = 374 V

TerminalBb = 376 V

TerminalB a = 375 V

As the terminal voltage across Bb = A a =B a and A-b> Voltage acrossAll OtherTerminals,

The Vector Group Test is confirmed as YNd1.

Result: _____________Vector group is ok____

** Voltage measured by FLUKE-189Digital Meter, manufactured by FLUKE,USA.




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2.4 Measurement of voltage ratio

Tap

Position

HT

Voltage

LT

Voltage

ACTUAL

RATIO

Measured RATIO

Phase-A Phase-B Phase-C

1 145200 11000 7.621 7.659 7.652 7.650

2 143550 11000 7.534 7.570 7.564 7.564

3 141900 11000 7.447 7.482 7.475 7.475

4 140250 11000 7.361 7.393 7.387 7.388

5 138600 11000 7.274 7.306 7.298 7.299

6 136950 11000 7.188 7.215 7.211 7.2107 135300 11000 7.101 7.128 7.123 7.122

8 133650 11000 7.014 7.035 7.034 7.034

9 132000 11000 6.928 6.951 6.946 6.945

10 130350 11000 6.841 6.862 6.857 6.856

11 128700 11000 6.754 6.773 6.769 6.769

12 127050 11000 6.668 6.685 6.680 6.681

13 125400 11000 6.581 6.598 6.592 6.592

14 123750 11000 6.495 6.509 6.503 6.504

15 122100 11000 6.408 6.420 6.416 6.416

16 120450 11000 6.321 6.332 6.328 6.32817 118800 11000 6.235 6.244 6.239 6.239

18 117150 11000 6.148 6.155 6.151 6.151

19 115500 11000 6.062 6.068 6.063 6.064

20 113850 11000 5.975 5.979 5.976 5.975

21 112200 11000 5.888 5.891 5.888 5.887

22 110550 11000 5.802 5.803 5.798 5.797

23 108900 11000 5.715 5.714 5.710 5.710

24 107250 11000 5.629 5.627 5.622 5.622

25 105600 11000 5.542 5.538 5.534 5.534

Remarks: The voltage ration between HT & LT side of the transformer for every TAP POSITION isOK. The vector group of this transformer is YNd1

** Measured by Vanguard Turn Ratio Meter (Model: ATRT-03, S/N-18661)

Manufactured by Vanguard Instrument Co., Inc.

** Calibrated by Cali-Labs Pv. Ltd., Bhopal, India




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2.5 Measurement of winding Insulation Resistance

Test Voltage = 5kVMean Transformer Oil Temperature = 30 C

Measured

After

Insulation Resistance (Giga Ohms) Remarks

HV E LV E HV LV

15 Sec. 9.12 4.60 8.35 Good

60 Sec. 13.10 7.40 11.50 Good

DAR 1.43 1.60 1.37 Good

Result:________Satisfactory_______

** Insulation Resistance measured by 5kV ElectronicBM !4Mega-ohm Meter & 5 kV Megger

manufactured by Megger Industries Ltd., England.




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test report pre ing desh energy tr 01

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