A8013209

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CESI

Centro Elettrotecnico Sperimentale Italiano Giacinto Motta spa

Via R. Rubattino 54 20134 Milano - Italia Telefono +39 022125.1 Fax +39 0221255440 http://www.cesi.it

Capitale sociale 8 550 000 Euro interamente versato Codice fiscale e numero iscrizione CCIAA 00793580150

Registro Imprese di Milano Sezione Ordinaria N. R.E.A. 429222 P.I. IT00793580150

Client MF Trasformatori s.r.l. – Calcinato (BS)

Tested equipment Non-enclosed three-phase dry-type power transformer, with encapsulated windings, for continuous duty, with cooling by air natural convection (AN): MF Trasformatori – 250 kVA - 15 kV / 0,4 kV

Tests carried out Verification of dynamic ability to withstand short-circuit

Standards/Specifications IEC 60076-11 Ed.1.0 (2004-05)

Test date from May 8, 2008 to May 8, 2008

The results reported in this document relate only to the tested equipment.

Partial reproduction of this document is permitted only with the written permission from CESI

No. of pages 12 No. of pages annexed 10

Issue date May 8, 2008

Prepared Unit LABORATORIES – M. Assolari

Verified Unit LABORATORIES – F. Pizzi

Approved Unit LABORATORIES – R. Nicolini

PUB

BL

ICA

TO

A80

1320

9 (P

AD

- 1

0565

54)

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M2001IG

Tests witnessed by /

Identification of the object not requested

Only for laboratory requirement, in order to reproduce the test conditions, all the laboratory data are contained in the document marked: ---

The measurement uncertainties of the test results reported in this document comply with the following limits: voltage : ± 5 % ; current : ± 5 % ; time : ± 5 %

The measurement uncertainties are estimated at the level of twice the standard deviation (corresponding, in the case of normal distribution, to a confidence level of about 95 %) and have to be considered as maximum estimated values referred to that type of measurement.

Laboratory information

Receipt date of the sample April 28, 2008

Test location CESI – Via Rubattino 54 – Milan

CESI testing team M. Cunego G. Avona M. Lodi

Test laboratory MP1 / P102

Activity code AN08LAP005

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M2027IG

Rated characteristics of the tested object assigned by the Client Dry-type power transformer Manufacturer MF Trasformatori s.r.l. – Calcinato (BS)Type -Manufacturer's serial number 250308/2Year of manufacturing 2008Number of phases 3Rated voltage of the high-voltage winding (primary winding) 15 kV ± 2 x 2,5 %Rated voltage of the low-voltage winding (secondary winding) 400 VRated voltage ratio 15 kV / 0,4 kVRated frequency 50 HzRated power 250 kVARated current of the high-voltage winding (primary winding) 9,62 ARated current of the low-voltage winding (secondary winding) 361 AShort-circuit impedance 5,77 %Connection symbol Dyn11 Cooling method AN Environmental class E2 – C2 – F1Total mass 1250 kg Characteristics of the windings Highest voltage for equipment applicable to the high-voltage winding 24 kVHighest voltage for equipment applicable to the low-voltage winding 3,6 kVRated insulation levels LI 125 AC 50 / LI 20 AC 10Insulation class F 100°C / F 100°CType of construction with circular concentric coilsHigh-voltage winding conductor aluminium wireLow-voltage winding conductor metal foil (aluminium) Name and signature of Client's witness:

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M2028IG

Verification of dynamic ability to withstand short-circuit Requested values Test current values were calculated neglecting the system impedance since such declared vale is less than 5% of the short-circuit impedance of the transformer.

Short-circuit current (*) Tap-changer position Ur ZSC X/R k x √2 r.m.s. value peak value

- kV % - - A A

0 15,00 5,77 3,909 2,077 6254 12991

+ + 15,75 5,76 4,104 2,100 6265 13158

- - 14,25 5,87 3,812 2,064 6147 12686

(*) Values of short-circuit current of the low-voltage winding (star-connected). Test arrangements and test procedures The transformer was tested connecting a three-phase supply to the high-voltage winding (primary winding). The low-voltage winding was short-circuited before the application of the voltage to the other winding of the transformer (pre -set short-circuit). During each test were recorded the line-to-line supply voltages, the phase currents of the low -voltage winding and the fault current, if any, between the mass (insulated) of the transformer and earth. Nine tests were performed (three tests on each limb): • three tests with the tap-changer on the principal tapping (with the maximum peak current on the middle limb), • three tests with the tap-changer in the position corresponding to the highest voltage ratio (with the maximum peak

current on one of the outer limbs), • three tests with the tap-changer in the position corresponding to the lowest voltage ratio (with the maximum peak current

on one of the other outer limbs).

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M2029IG

Short-circuit tests with three-phase current Test circuit: M0002 Test frequency: 50 Hz Reference number of the oscillograms: A8/013209 Conditions of the transformer before the tests: as supplied by the Client Transformer prearranged on the voltage ratio: 15 kV / 0,4 kV Date: May 8, 2008

Tap-changer No-load Test current

Test Oscillogram position supply peak r.m.s. average Duration

voltage value value value

No. No./sheets - V A A A s 4341

9038 4289 1 1/1 0 - 4376

4335 0,1

6210 12810 6164 2 2/1 0 -

6278 6217 0,5

6213 12780 6164 3 3/1 0 -

6280 6219 0,5

6236 12750 6155 4 4/1 0 -

6278 6223 0,5

6188 6122 5 5/1 + + -

12760 6203 6171 0,5

6182 6128 6 6/1 + + -

12810 6233 6181 0,5

6287 6186 7 7/1 + + -

12800 6319 6264 0,5

12470 6120 6077 8 8/1 - - - 6161

6119 0,5

12440 6105 6046 9 9/1 - - - 6163

6105 0,5

12500 6132 6054 10 10/1 - - - 6165

6117 0,5

Conditions of the transformer after the tests: see notes

- Externally didn’t show any sign of damage or deformation

M2032IG

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Measurement of short-circuit inductance The measurement of short-circuit inductance was performed before the short-circuit tests and after every series of three tests by means of a Schering bridge (Maxwell diagram) which allows a reproducibility of at least ± 0,2%. For all measurements the transformer was set-up in the following conditions: • the tap-changer was placed in the position corresponding to the highest voltage ratio, • the terminals of the low-voltage winding were short-circuited, • the measurement points were applied to the terminals of the high-voltage winding, delta-connected. Date: May 8, 2008

U-V U-W V-W U-V U-W V-W U V W U V W+ + 339,60 338,40 341,17 - - - 509,20 513,95 505,63+ + after the test no. 4 339,96 338,52 341,38 0,11 0,04 0,06 509,94 514,23 505,65 0,14 0,06 0,00+ + after the test no. 7 340,38 338,92 341,68 0,23 0,15 0,15 510,64 514,57 506,29 0,28 0,12 0,13+ + after the test no. 10 340,42 338,96 341,72 0,24 0,17 0,16 510,70 514,63 506,35 0,29 0,13 0,14

calculated for single limb from the initial value

before the tests

short-circuit inductance variation[mH] [%] [mH] [%]tap-changer

position measurement effected

short-circuit inductance variation

measured at the terminals from the initial measurement

Maximum variation of short-circuit inductance stated by Standard: 4 %.

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M0002IG

Test circuit M0002

The symbols used in this diagram are the same as those on the oscillograms.

Correspondence between laboratory circuit phase and test object terminal

Laboratory circuit phase Test object terminal

R U

S V

T W

M2516IG

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Photo no. 1

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M2009IG

Photo no. 2

Photo no. 3

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M2091IG

Laboratory information Requested values and test circuit parameters Date: May 8, 2008

Tap-changer Requested values Synchronous Time Test position peak r.m.s. test XAT RAT make-switch of the

current current duration position test No. - A A s Ω Ω °el. -

63,5 15,2 1 0 - 4000 0,1

98 9.55am

20,0 7,6 2 “ 12991 6254 0,5

98 10.10am

“ “ 3 “ “ “ 0,5

98 10.15am

“ “ 4 “ “ “ 0,5

98 10.20am

18,25 “ 5 + + 13158 6265 0,5

38 10.45am

“ “ 6 “ “ “ 0,5

38 10.50am

“ “ 7 “ “ “ 0,5

38 10.55am

22,5 “ 8 - - 12686 6147 0,5

158 11.10am

“ “ 9 “ “ “ 0,5

158 11.15am

“ “ 10 “ “ “ 0,5

158 11.20am

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M2048IG

Laboratory information Date: May 8, 2008 Characteristics of supply circuit

Tests Supply OTE MV OTE LV from to K position K position

1 10 23 kV Lambrate 1,238 - - -

Characteristics of measuring system

National Instrument Krenz Measure Transducer

SCXI PXI channel - ref. position No. No. No. Ir C1+C4 1

Vrs A1+A3 2 Is C2+C4 3

Vst A1+A2+A3 4 It C3+C4 5

Vtr A2+A3 6 Itk D1+D2 7

inductance P1+P2

Symbols assigned in “ref.” column refer to the measuring equipment listed in page “Laboratory P102 – MP1. Measuring system characteristics.” Other measuring equipment: Ohmmeter CESI number: -

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M2085IG

Laboratory P102 – MP1 Measuring system characteristics

Ref. Type CESI No. Ref. Type CESI No.

A1 Voltage transformer TV2 – R-S 9032 K1 Shunt 160 μΩ – 30 kA 5559 A2 Voltage transformer TV2 – S-T 9033 K2 Shunt 160 μΩ – 30 kA 5560 A3 Resistive dividers for TV2 14142 K3 Shunt 160 μΩ – 30 kA 5561 B1 Resistive divider K= 206,5 11465 L1 Shunt 111 mΩ 9754 B2 Resistive divider K= 206,5 11466 L2 Shunt 111 mΩ 9758 B3 Resistive divider K= 206,5 11467 L3 Shunt 111 mΩ 9759 B4 Resistive divider K= 206,5 11468 = KRENZ TRC1 13119 C1 Current transformer TA2 – R 17060 = KRENZ TRC2 13120 C2 Current transformer TA2 – S 17061 M1 Voltage transformer 24 kV / 100 V 3387 C3 Current transformer TA2 – T 17059 N1 Divider RC 30 kV 14677 C4 Resistive burden for TA2 5562 N2 Divider RC 30 kV 14678 D1 Current transformer 4000 A / 5 A 14466 N3 Divider RC 30 kV 14679 D2 Resistive burden for TA3 17072 N4 Divider RC 30 kV 11990 E1 Shunt 40 μΩ – 100 kA – R 8231 N5 Divider RC 30 kV 11991 E2 Shunt 40 μΩ – 100 kA – S 8232 N6 Divider RC 30 kV 11992 E3 Shunt 40 μΩ – 100 kA – T 8230 P1 Schering bridge 696 F1 Shunt 1,33 mΩ – 5 kA – R 7965 P2 Resistive box 8451 F2 Shunt 1,33 mΩ – 5 kA – S 7966 R1 Micro-ohmmeter MOM600A 14204 F3 Shunt 1,33 mΩ – 5 kA – T 7968 S1 Micro-ohmmeter OM21 14643 G1 Shunt 1,6 mΩ – 5 kA – additional 7964 T1 Megger METRISO 13139 G2 Shunt 1,6 mΩ – 5 kA – additional 7963 U1 Thermocouples calibrator CALIS 5 23138 G3 Shunt 1,6 mΩ – 5 kA – additional 7967 V1 Digital multimeter FLUKE 8060A 17519 H1 Shunt 80 μΩ – 100 kA 5524 Z1 Temperature probe FLUKE 80T-150U 3831 H2 Shunt 80 μΩ – 100 kA 5525 H3 Shunt 80 μΩ – 100 kA 5526 J1 Electro-optical link for thermocouple T 13372 J2 Electro-optical link for thermocouple T 14556 J3 Electro-optical link for thermocouple J 17074 J4 Electro-optical link for thermocouple J 17076 J5 Electro-optical link for thermocouple J 17078 J6 Electro-optical link for thermocouple K 22463 J7 Electro-optical link for thermocouple K 22465 J8 Electro-optical link for thermocouple K 22467 J9 Electro-optical link for thermocouple K 22469

Measuring software: SAD – P102 Software release: 4.2 – 31/12/2002 Hardware: VAX 4200 with VMS 5.4 Prepared by: G. Zuccalà Date: 19/05/2006