mumi 1_1083100a0002

TRANSFORMER CONDITION ASSESSMENT

Project No: File: MUMI 1_1083100A0002 of 12

DOBLE ENGINEERING AFRICA

TRANSFORMER DIAGNOSTIC TESTING AT MUMI 1 SUBSTATION

This report was prepared on the10th June 2014 by:

Kamendren Govender

Principal Engineer

CLIENT: MATREX



REPORT DETAILS

CLIENT Matrex ADDRESSEE

SITE MUMI 1 Substation JOB DESCRIPTION Transformer Condition Assessment REPORT PREPARED BY Kamendren Govender DATE REPORT COMPLETED 10th June 2014 REPORT AUTHORISED BY Luwendran Moodley CLIENT ORDER NUMBER QS1405-19

Copyright © 2007 Doble Engineering Africa Limited All rights reserved. No part of this publication may be produced stored in a retrieval system or transmitted in any form by any means electronic mechanical photocopying recording or otherwise without the prior written permission of Doble.

Indemnity This document may not be distributed or used outside the client for whom it is prepared except with written authorization from Doble. Doble disclaims all liability for any loss damage injury or other consequence whatsoever arising from any unauthorized use howsoever caused including any such resulting from error omission or negligence in its application.



Table of Contents 1. Executive Summary...............................................................................................4

1.1. Findings ..............................................................................................................4 1.2. Recommendations ..............................................................................................4 2.0 Analysis and Observations ..................................................................................5

2.1. Transformer Details ..........................................................................................5 2.2. Condition Analysis ...........................................................................................5 2.2.1. Electrical Test Findings ......................................................................................5 2.2.2 Oil Test Findings .............................................................................................. 12



1. Executive Summary

1.1. Findings

Doble Engineering Africa was requested by Mutanda Mining Company to perform diagnostic tests and analysis on a transformer based on electrical tests. This report covers the final findings based on our studies of the transformer with serial number: 1083100A0002 manufactured by Hangzhou-Qiantang-River-Electric-Group and located at MUMI 1 Substation. The winding power factor and capacitance results are within acceptable limits.

The bushing power factor and capacitance results are within acceptable limits.

The excitation currents are within acceptable limits.

The ratio test revealed no significant concerns with all ratios being within the acceptable limits. The impedance results are within acceptable limits. The DC winding resistance tests results are within acceptable limits. The insulation resistance test are within acceptable limits. The SFRA indicated no winding deformation on both the HV and LV Winding.

1.2 Recommendations The transformer demonstrates acceptable test results and may be suitable for continued service with routine maintenance and diagnostic testing.



2. Analysis and Observations

2.1 Transformer Details

The transformers details are given in Table 1.

Table 1: Transformers Details

Substation MUMI 1 Substation Unit T2

Serial Number 1083100A0002 Manufacturer Hangzhou-Qiantang-River-Electric-Group

Year of Manufacturer 2008 Voltage 120/22 kV

VA Rating 24 MVA

2.2 Condition Analysis

2.2.1 Electrical Test Findings

2.2.1.1 Windings Insulation

Results and Analysis The winding power factor values are given in Table 2.

Table 2: Winding Power Factor and Capacitance Test Results

Measured Voltage (kV) Power Factor (%) Capacitance (pF)

HV winding to earth 10 0.22 2 750.48 Between HV and LV winding 10 0.17 3 837.77 LV winding to earth 10 0.16 6 881.44

All winding power factor and capacitance results are within acceptable limits. 2.2.1.2 Bushing Insulation Results and Analysis The bushing power factor and capacitance results are given in Table 3.

Table 3: Bushing Power Factor and Capacitance Test Results

Measured Serial Number

Voltage (kV) Power Factor (%) Capacitance (pF)

HV Red Phase 082034 10 0.26 340.75 HV Yellow Phase 082036 10 0.25 341.66 HV Blue Phase 082032 10 0.23 332.67

All bushing power factor and capacitance results are within acceptable limits.



2.2.1.3 Excitation Current Tests Results and Analysis The results from the excitation current tests are shown in Table 4.

Table 4: Excitation Current Test Results

Tap A Phase B Phase C Phase

Current (mA) Loss (W) Current (mA) Loss (W) Current (mA) Loss (W)

1 26.12 215.86 19.00 157.69 27.82 224.79 2 26.79 220.42 19.48 161.19 28.32 228.45 3 27.45 225.17 19.98 164.82 28.92 232.93 4 28.15 230.24 20.49 168.55 29.58 237.79 5 28.82 235.30 21.03 172.50 30.24 242.80 6 29.52 240.51 21.57 176.50 30.94 248.09 7 30.25 246.05 22.12 180.60 31.66 253.57 8 30.95 251.52 22.69 184.87 32.38 259.18 9 31.74 257.50 23.59 189.30 33.15 265.13

10 32.87 263.31 24.22 193.95 34.29 270.93 11 33.69 269.63 24.89 198.78 35.10 277.14 12 34.55 276.17 25.58 203.83 35.93 283.59 13 35.45 283.07 26.28 209.05 36.79 290.30 14 36.36 290.05 27.06 214.66 37.69 297.30 15 37.32 297.50 27.83 220.42 38.61 304.57 16 38.33 305.26 28.61 226.34 39.57 312.13 17 39.34 313.16 29.40 232.69 40.57 320.00

The excitation currents are within acceptable limits.



2.2.1.4 Ratio Test Results and Analysis

The results of the ratio test for each phase and tap position shall be within ± 0.5 % of the nameplate data. The results from the ratio tests are given in Table 5.

a) HV Winding

Table 5: Ratio Test Results

Tap A Phase B Phase C Phase Min Max

1 3.31 3.31 3.31 3.29 3.32

2 3.27 3.27 3.27 3.25 3.28

3 3.23 3.23 3.23 3.21 3.24

4 3.19 3.19 3.19 3.17 3.20

5 3.15 3.15 3.15 3.13 3.16

6 3.11 3.11 3.11 3.09 3.12

7 3.07 3.07 3.07 3.05 3.08

8 3.03 3.03 3.03 3.01 3.04

9 2.99 2.99 2.99 2.97 3.00

10 2.95 2.95 2.95 2.93 2.96

11 2.91 2.91 2.91 2.89 2.92

12 2.87 2.87 2.87 2.85 2.88

13 2.83 2.83 2.83 2.82 2.84

14 2.79 2.79 2.79 2.78 2.80

15 2.75 2.76 2.75 2.74 2.76

16 2.71 2.72 2.72 2.70 2.73

17 2.67 2.68 2.68 2.66 2.69

The ratio measurements are within acceptable limits. 2.2.1.5 Impedance Test

Results and Analysis The impedance test results are shown in Table 6. HV to LV: Three Phase Equivalent Tests

Table 6: HV to LV: Three Phase Equivalent Test Results

Tap Nameplate Impedance

(%) Measured Impedance

(%) Change in Impedance

(%)

1 10.3 10.37 0.66

5 10 10.08 0.85

17 9.2 9.82 6.69

The impedance results are within acceptable limits.



2.2.1.6 DC Winding Resistance

Results and Analysis The DC winding resistance tests were performed on all windings and are shown on Tables 7 and 8. a) HV Winding

Table 7: HV DC Winding Resistance Test Results


Resistance (ΩΩΩΩ) Resistance (ΩΩΩΩ) Resistance (ΩΩΩΩ) 1 1.470 1.467 1.471 2 1.444 1.440 1.444 3 1.416 1.413 1.417 4 1.390 1.387 1.391 5 1.363 1.360 1.364 6 1.337 1.333 1.337 7 1.310 1.307 1.311 8 1.283 1.280 1.284 9 1.255 1.251 1.254

10 1.283 1.280 1.284 11 1.310 1.307 1.310 12 1.337 1.333 1.337 13 1.362 1.360 1.363 14 1.389 1.386 1.390 15 1.415 1.413 1.416 16 1.442 1.440 1.443 17 1.469 1.466 1.470

The DC winding resistance is within acceptable limits. b) LV Winding

Table 8: LV DC Winding Resistance Test Results


Resistance (mΩΩΩΩ) Resistance (mΩΩΩΩ) Resistance (mΩΩΩΩ)

1 75.82 75.81 75.84 The DC winding resistance test results are within acceptable limits 2.2.1.7 Insulation Resistance Results and Analysis The insulation resistance test results are given in Table 9.

Table 9: Insulation Resistance Test Results

Measure Test Result

Core – Earth 19.6 GΩ The insulation resistance test results are within acceptable limits.



2.2.1.8 SFRA Test

Results and Analysis The results from the SFRA tests are given in Figures 1 to 3.

a) HV Winding Open Circuit

Figure 1: HV Winding Open Circuit

Note: The deviation of the middle phase (white phase or B phase) in the lower frequencies is normal due to the difference in the reluctance of the core for the middle phase compared to the two outside phases. The comparison between the phases finds that the responses demonstrate a characteristic pattern and has good correspondence across the entire frequency range. These responses do not indicate winding deformation.



b) LV Winding Open Circuit

Figure 2: LV Winding Open Circuit

Note: The deviation of the middle phase (white phase or B phase) in the lower frequencies is normal due to the difference in the reluctance of the core for the middle phase compared to the two outside phases. The comparison between the phases finds that the responses demonstrate a characteristic pattern and has good correspondence across the entire frequency range. These responses do not indicate winding deformation



c) HV Winding Short Circuit

Figure 3: HV Winding Short Circuit

The short circuit response revealed no resistance change between the phases. These responses do not indicate winding deformation.



2.2.2 Oil Assessment a) Oil Quality i) Moisture Content The moisture content (9 ppm) is within acceptable limits. ii) Dielectric Strength The dielectric strength (69 kV) is within acceptable limits. iii) Acidity The acidity (0.01) is within acceptable limits. b) Paper Degradation

The concentration of the paper degradation product of furans measured in oil is 0.06ppm, which relates to a degree of polymerization (DP) of 824 respectively. The furan level suggests the normal paper aging.

c) Dissolved Gas Analysis The only DGA sample is indicative of a normal operating transformer. This is shown in Figure 4.

Figure 4: DGA Signature

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100

08/05/14

TC

G (

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Sample Date

Transformer: 1083100A0002

CO H2 CH4 C2H4 C2H6 C2H2

mumi 1_1083100a0002

Documents

transformer details

acceptable limits

1083100a0002 page

condition analysis

electrical test findings

capacitance results

final findings

oil test findings