1 | POWER TRANSFORMER | | | |
| | | | |
1.1 | Manufacturer & Place of manufacturing | | | HEMG |
1.2 | Type designation | | | OSFSZ-200000/400 |
1.3 | Type | | | |
| Three phase Autotransformer, oil-immersed, core type with tertiary winding | | | Yes |
| | | | |
1.4 | Standards | | | IEC 60076, 60137, 60214 |
| | | | |
1.5 | Altitude | m | | 216 |
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1.6 | Ambient temperature | | | |
| - Maximum | ºC | | 40 |
| - Annual average | ºC | | 30 |
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1.7 | Mounting | | | Outdoor |
| | | | |
1.8 | Rated voltage ratio | kV | | 400 |
| 220 |
| 11 |
1.9 | Rated frequency | Hz | | 50 |
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1.1 | Vector group (3 phase group connection) | | | YNa0d11 |
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1.11 | Cooling- 2-stage | | | ONAN/ ONAF1/ ONAF2 |
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1.12 | Function of tertiary winding (TV) | | | Aux. supply |
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1.13 | Method of earthing | | | |
| - HV winding | | | Solid |
| - LV winding | | | Solid |
| - TV winding | | | - |
| | | | |
1.14 | Type of windings (graded/ non-graded) | | | |
| - HV winding (Series) | | | Graded |
| - LV winding (Common) | | | Graded |
| - TV winding | | | Non-graded |
| | | | |
1.15 | Rated voltage of windings (Ur) | | | |
| - HV winding | kV | | 400 |
| - LV winding | kV | | 220 |
| - TV winding | kV | | 11 |
| Note*: approximate; to manufacturer's preference | | | |
| | | | |
1.16 | Highest voltage for equipment (Um) | | | |
| - HV winding | kV | | 420 |
| - LV winding | kV | | 245 |
| - TV winding | kV | | 12 |
| | | | |
1.17 | Rated lightning impulse withstand voltage at: | | | |
| - HV terminal | kV | | 1425 |
| - LV terminal | kV | | 1050 |
| - Neutral terminal | kV | | 480 |
| - TV winding | | | 75 |
| | | | |
1.18 | Rated switching impulse voltage | | | |
| - HV terminal | kV | | 1050 |
| - LV terminal | kV | | 850 |
| | | | |
1.19 | Rated power frequency withstand voltage at | | | |
| - HV terminal (design value) | kV | | 630 |
| - HV test value (ACLD U1) | kV | | 436 |
| - HV test value (ACLD U2 PD measurement) | kV | | 388 |
| - LV terminal (design value) | kV | | 460 |
| - Neutral terminal | kV | | 70 |
| - TV terminal | kV | | 28 |
| | | | |
1.2 | Rated power at site conditions (ONAF2 or OFAF), HV & LV | MVA | | 200 |
| | | | |
1.21 | Rated power at site conditions (ONAN) | MVA | | 120 |
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1.22 | Rated power of tertiary at site conditions (Full cooling) | MVA | | 70 |
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1.23 | Maximum temperature rise at rated power at: | | | |
| - Windings | K | | 55 |
Marikani |
|
| - Hot spot of windings | K | | 68 |
Marikani |
|
| - Top oil | K | | 50 |
Marikani |
| - Oil at inlet of cooler | K | | Approx 22 |
| - Oil at outlet of cooler | K | | Approx 50 |
| - Core | K | | Approx 75 |
| | | | |
1.24 | Temperature of winding due to short circuit duration of 2s at rated load | | | |
| - HV side short circuit rating of 31.5kA | ºC | | 250 |
| - LV side short circuit rating of 31.5kA | ºC | | 250 |
| | | | |
1.25 | No-load losses at rated voltage and rated frequency | kW | | 45 |
| | | | |
1.26 | Load losses at 75ºC, and rated frequency: | | | |
| - ONAF2 or OFAF rated power and principal tapping | | | 288 |
- ONAF2 or OFAF rated power and maximum voltage ratio | |
- ONAF2 or OFAF rated power and minimum voltage ratio | 278 |
- At ONAN rated power and principal tapping | |
| 350 |
| |
| 105 |
| | | | |
1.27 | Total auxiliary losses at fully load | kW | | Approx 10 |
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1.28 | Maximum current density at rated power: | | | |
| - HV winding | A/mm2 | | Approx 2.0 |
| - LV winding | A/mm2 | | Approx 2.0 |
| - TV winding | A/mm2 | | Approx 3.6 |
| - Tapping | A/mm2 | | Approx 3.6 |
| | | | |
1.29 | Symmetrical short circuit through current (duration 2s) at system fault rating | | | |
| - HV terminals (31.5kA) | kA | | 31.5 |
| - LV terminals (31.5kA) | | | 31.5 |
| | | | |
1.3 | Magnetising current (HV winding) | | | |
| - At 90% rated voltage | A | | Approx0.7 |
| - At 100% rated voltage | A | | Approx0.9 |
| - Ar 110% rated voltage | A | | Approx6.8 |
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1.31 | Maximum flux density in iron at rated voltage, power frequency and principal tapping at: | | | |
| - Wound limbs | T | | Approx1.7 |
| - Unwound limbs | T | | Approx1.7 |
| - Yokes | T | | Approx1.7 |
| - Shields | T | | Approx1.7 |
1.32 | Maximum flux density in iron at power frequency, principal tapping and 105% rated voltage at: | | | |
| - Wound limbs | T | | Approx 1.78 |
| - Unwound limbs | T | | Approx 1.78 |
| - Yokes | T | | Approx 1.78 |
| - Shields | T | | Approx 1.78 |
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1.33 | Type pf tap changing | | On-load | On-load |
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1.34 | Manufacturer of on-load tap changer | | | MR |
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1.35 | Type designation of on-load tap changer | | | M500-72.5/C-10193W |
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1.36 | Tapped winding | | HV | HV |
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1.37 | Type of flux voltage variation | | V.F.V.V | V.F.V.V |
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1.38 | Tapping range | | -1 | -1 |
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1.39 | Tapping step | | 1.25% | 1.25% |
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1.4 | Number of steps (positions) | | 16 (17) | 16 (17) |
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1.41 | Arrangement of tappings (Linear, Coarse/ Fine, Reversing) | | | Reversing |
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1.42 | Automatic voltage control | | Yes | Yes |
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1.43 | HV - LV Impedance voltage range at 75°C, rated frequency and full rating: | | | |
| - At principal tapping | % | >14% | >14% |
| - At maximum voltage ratio | % | >14% | >14% |
| - At minimum voltage ratio | % | >14% | >14% |
| | | | |
1.44 | Impedance voltage HV-TV (principle tapping) at 70MVA | % | | Approx 22.5 |
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1.45 | Resistance of winding at 75ºC and principal tapping: | | | |
| - HV side | Ω/phase | | Approx 0.53 |
| - LV side | Ω/phase | | Approx 0.58 |
| - TV | Ω/phase | | Approx 0.029 |
1.46 | Terminal connection | | | |
| - HV terminal | | Outdoor bushing | Outdoor bushing |
| - LV terminal | | Outdoor bushing | Outdoor bushing |
| - Neutral terminal | | Outdoor bushing | Outdoor bushing |
| - TV terminal | | Outdoor bushing | Outdoor bushing |
| | | | |
1.47 | Bushing Creepage Distance (IEC class IV=31mm/kV) | | | |
| - HV terminal (420kV) | mm | 13020 | 13020 |
| - LV terminal (245kV) | mm | 7595 | 7595 |
| - Neutral terminal (36kV) | mm | ≥900 | ≥900 |
| - TV terminal (12kV) | mm | 372 | 372 |
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1.48 | Cable box insulation | | | |
| - HV terminal | | N/A | N/A |
| - LV terminal | | " | N/A |
| - HV Neutral terminal | | " | N/A |
| - LV Neutral terminal | | " | N/A |
| - Tertiary | | " | N/A |
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1.49 | Isolating links for test purposes | | | |
| - HV terminal | | N/A | N/A |
| - LV terminal | | " | N/A |
| - Tertiary terminal | | " | N/A |
1.5 | Current transformers | | | |
| HV- Bushing turrets | | Refer to Tender Drawings | |
| | | | |
| - Number of cores | | | 3 |
| - Rated extended primary current | | | 500, 1000/500, 1000/500 |
| - Ratio (TR= turns ratio) | | | |
| •I core | A | | 500/1 |
| •II core | A | | 1000/500/1 |
| •III core | A | | 1000/500/1 |
| - Class | | | |
| •I core | | | 5P20 |
| •II core | | | 5P20 |
| •III core | | | 5P20 |
| - Knee point voltage (Ek) | | | |
| •I core | V | | 1665 |
| •II core | V | | 3330/ 1665 |
| • III core | V | | 3330/ 1665 |
| - Exciting current (IE) at EK | | | |
| •I core | mA | | Will provide measured value |
| •II core | mA | | Will provide measured value |
| •III core | mA | | Will provide measured value |
| - Rated output (Burden to be 25-100% rated burden) | | | |
| •I core | VA | | 30 |
| •II core | VA | | 30 |
| •III core | VA | | 30 |
| | | | |
| LV line (Only AIS connections) | | | |
| | | | |
| - Number of cores | | | 3 |
| - Rated extended primary current | | | 1500, 750,750 |
| - Ratio (TR= turns ratio) | | " | 1500/750/1; 750/1; 750/1 |
| - Class | | " | 5P20 |
| - Knee point voltage (Ek) | | " | 4995, 2498, 2498 |
| - Exciting current (IE) at Ek | | " | Will provide measured value |
| - Rated output (Burden to be 25-100% rated burden) | | " | 30 |
| | | | |
| Neutral (HV REF) | | | |
| | | | |
| - Number of cores | | | 1 |
| - Rated extended primary current | | | 500 |
| - Ratio (TR= turns ratio) | | | |
| * I core | A | | 500/1 |
| - Class | | | |
| * I core | | | 5P20 |
| - Knee point voltage (Ek) | | | |
| * I core | V | | 1665 |
| - Exciting current (IE) at Ek | | | |
| * I core | mA | | Will provide measured value |
| - Rated output (Burden to be 25-100% rated burden) | | | |
| * I core | VA | | 15 |
| | | | |
| Neutral - ends | | | |
| | | | |
| - Number of cores | | | 1 |
| - Rated extended primary current | | | 500 |
| - Ratio (TR= turns ratio) | | | |
| •I core | A | | 500/1 |
| - Class | | | |
| •I core | | | 5P20 |
| - Knee point voltage (Ek) | | | |
| •I core | V | | 1665 |
| - Exciting current (IE) at Ek | | | |
| •I core | mA | | Will provide measured value |
| - Rated output (Burden to be 25-100% rated burden) | | | |
| •I core | VA | | 15 |
| All class PX CTs shall have a rated secondary current, ISN | A | | 1 |
| | | | |
| Tertiary | | | |
| - Number of cores | | | N/A |
| - Rated extended primary current | A | | N/A |
| - Ratio (TR= turns ratio) | | | |
| * I core | | | N/A |
| * II core | | | N/A |
| - Class | | | |
| * I core | | | N/A |
| * II core | | | N/A |
| - Knee point voltage (Ek) | | | |
| * I core | V | | N/A |
| * II core | V | | N/A |
| - Exciting current (IE) at Ek | | | |
| * I core | mA | | N/A |
| * II core | mA | | N/A |
| - Rated output (Burden to be 25-100% rated burden) | | | |
| * I core | VA | | N/A |
| * II core | VA | | N/A |
| | | | |
1.51 | Number of coolers per transformer | | | Approx 10 |
| | | | |
1.52 | Number of stand-by coolers | | | N/A |
| | | | |
1.53 | Number of stand-by fans | | | 1 |
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1.54 | Rating of each cooler | kW | | 0.75 |
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1.55 | Oil | | | |
| - Manufacturer | | | Nynas Nitro |
| - Type designation | | | GBN1 |
| - Standards | | IEC 60296 | IEC 60296 |
| - Minimum flash point | ºC | | 140 |
| - Viscosity | | | |
| * at 20ºC | mm2/s | | IEC 60296 |
| * at 50ºC | mm2/s | | IEC 60296 |
| * at 80ºC | mm2/s | | IEC 60296 |
| - Maximum dielectric strength for 1 min. | kV | | 70 |
| - Dielectric factor | | | 0.005 |
| - Acidity (neutralization value) | mgKOH/g | | 0.01 |
| | | | |
1.56 | Oil preservation system | | Air-bag | Air-bag |
1.57 | Types and arrangement of winding: | | | |
| - HV winding | | | Disc |
| - LV winding | | | Disc |
| - TV winding | | | Disc |
| - Regulating | | | Disc |
| - Windings arrangement (i.e. Core/ TV/ LV/ HV/ Taps) | | | Core/ TV/Taps/ LV/ HV/ |
1.58 | Conductor material (e.g., copper, work hardened copper, etc.) | | | |
| - HV windings | | | Work hardened copper |
| - LV windings | | | Work hardened copper |
| - TV windings | | | Work hardened copper |
| - Regulating windings | | | Work hardened copper |
| - Connecting leads from winding to tap changer | | | Work hardened copper |
1.59 | Conductor insulation: | | | |
| - HV windings | | | Paper |
| - LV windings | | | Paper |
| - TV windings | | | Paper |
| - Regulating windings | | | Paper |
| - Connecting leads from winding to tap changer | | | Paper |
1.6 | Calculated thermal time constant | | | |
| - ONAN cooling | min | | Oil:210 windings:10 |
| - Full cooling | min | | Oil:90 windings:7 |
| | | | |
1.61 | Oil circulation (i.e., natural/ partially directed/ directed) | | | |
| To the windings: | | | |
| - HV windings (Series) | | | Natural |
| - LV windings (Common) | | | Natural |
| - Regulating windings | | | Natural |
| - TV windings | | | Natural |
| Through the windings: | | | |
| - HV windings (Series) | | | Derected |
| - LV windings (Common) | | | Derected |
| - Regulating windings | | | Natural |
| - TV windings | | | Derected |
1.62 | Core construction: | | | |
| - Taped/ banded/ bolted limbs | | | Banded limbs |
| - Taped/ banded bolted yokes | | | Banded yokes |
| - Taping / banding material | | | Epoxy-bound bandage |
| - Number of limbs | | | 3 |
| - Number of limbs wound | | | 3 |
| - Type of joint in magnetic core (90% butt, overlap, mitre, etc.) | | | Overlap |
| - Type of core steel | | | 23RK85 |
| - Specific loss of core steel at 1.5 tesla | W/kg | | Approx 0.7 |
| | | | |
1.63 | Thickness of transformer tank | | | |
| - Sides | mm | | 10 |
| - Bottom | mm | | 10 |
| - Top | mm | | 25 |
| | | | |
1.64 | Material of transformer tank | | | Q235 |
| | | | |
1.65 | Thickness of radiator plates | mm | | 1 |
| | | | |
1.66 | Total volume of conservator | Litre | | Approx 4000 |
| | | | |
1.67 | Minimum volume of conservator between highest and lowest levels as percentage of total cold oil at 15ºC volume of transformer | | 7.50% | 7.50% |
| | | | |
1.68 | Volumetric expansion of oil from 0ºC to 90ºC | m3 | | Approx 5.7 |
| | | | |
1.69 | Pressure increase inside tank due to expansion of oil | | | N/A |
| | | | |
1.7 | Masses of transformer | | | |
| - Core and coils | kg | | Approx 93000 |
| - Total mass excluded oil | kg | | Approx 140000 |
| - Oil mass * in tank | kg | | Approx 61000 |
| * in radiators | kg | | Approx 2500 |
| * total | kg | | Approx 81000 |
| - Total mass | kg | | Approx 221000 |
| | | | |
1.71 | Mass of transformer as arranged for transport (heaviest part) | kg | | Approx 120000 |
| | | | |
1.72 | Dimensions of transformer arranged for transport | | | |
| - Height | m | | |
| - Width | m | | |
| - Length | m | | |
| | | | |
1.73 | Filling medium of transformer tank for shipment | | | Dry air |
| | | | |
1.74 | Maximum sound pressure level (NEMA TR1- 5dB(A)) | dB(A) | 82 | 82 |
1.75 | Conservator vessel, radiators, fan grilles, control boxes or cubicles and pipework anticorrosion protection | | Hot dip galvanized and painted | Hot dip galvanized and painted |
| | | | |
1.76 | Tank anticorrosion protection | | | Painted |
| | | | |
1.77 | Supply voltage for transformer auxiliaries | V | 415/ 240 AC | 415/ 240 AC |
| | | | |
1.78 | Control/ Protection voltage | V | 110 DC | 110 DC |
| | | | |
1.79 | Manufacturer quality assurance | | Yes | Yes |
| - According to ISO 9000, 9001, 9002, 9003 and 9004 | | validity | validity |
| | | | |
1.8 | Type test certificate to be issued by: | | | |
| - Independent laboratory or independently witnessed type test certificate | | Yes | Yes |
| | | | |
1.81 | Special Tests to be performed: | | | |
| As Type test= T | | | |
| As Routine test= R | | | |
| - Dielectric test- Chopped wave lightning impulse | | Yes (R) | Yes (R) |
| - Dielectric test- Short duration AC (ACSD) | | No | No |
| - Measurement of zero-sequence impedance | | N/A | N/A |
| - Determination of sound levels | | Yes (T) | Yes (T) |
| - Measurement of harmonics of no-load current | | Yes (R) | Yes (R) |
| - Measurement of power of fan motors & oil pumps | | Yes (T) | Yes (T) |
| - Determination of capacitance, windings to earth and between windings | | Yes (R) | Yes (R) |
| - Measurement of insulation resistance to earth and loss angle of insulation system capacitances | | Yes (R) | Yes (R) |
| - Vibration test | | No | No |