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09/06/2019

Technical Specification of Three Phase Transformer

The following technical Specification is provided by the Manufacturer of transformer.
  • Name of Manufacturer
  • Service
kVA rating

  1. HV winding ( kVA )
  2. IV ( Intermediate voltage ) winding ( kVA )
  3. LV winding ( kVA )
Rated voltage
  1. HV winding ( kV )
  2. IV ( Intermediate voltage ) winding ( kV )
  3. LV winding ( kV )
  • Rated frequency
  • Number of phases
Connection
  1. HV winding
  2. IV winding
  3. LV winding
Connection symbol
  1. High voltage – Intermediate voltage
  2. High voltage – Low voltage

Tapings
  1. Range
  2. Number of steps
  3. High voltage / Intermediate voltage / Low voltage variations

Reference ambient temperatures
  1. Maximum ambient temperature ( oC )
  2. Maximum daily average ambient air temperature ( oC )
  3. Maximum yearly weighted average ambient temperature ( oC )
  4. Minimum ambient air temperature ( oC )
  5. Maximum cooling water temperature ( oC )
  • Type of cooling
Temperature rise
  1. Top oil ( oC )
  2. Windings ( oC )
Total loss at rated voltage at principal tapping and rated frequency ( kW )
  1. Component loss
  2. No load loss at rated voltage on principal tapping and at rated frequency ( kW )
  3. Load loss at rated current at principal tapping at 75 oC ( kW )
  • Impedance voltage at rated current for the principal tapping
  1. HV – IV ( Percent )
  2. HV – LV ( Percent )
  3. IV – LV ( Percent )
Reactance at rated current and rated frequency
  1. HV – IV ( Percent )
  2. HV – LV ( Percent )
  3. IV – LV ( Percent )
  • No load current at rated voltage and rated frequency ( Percent )
  • Input to cooling plant ( kW )
  • Insulation level
( a ) Separate source power frequency voltage withstand
  1. HV winding ( kV RMS )
  2. IV winding ( kV RMS )
  3. LV winding ( kV RMS )

( b ) Induced over voltage withstand
  1. HV winding ( kV RMS )
  2. IV winding ( kV RMS )
  3. LV winding ( kV RMS )

( c ) Full wave lighting impulse withstand voltage
  1. HV winding ( kV Peak )
  2. IV winding ( kV Peak )
  3. LV winding ( kV Peak )

( d ) Switching impulse withstand voltage
  1. HV winding ( kV Peak )
  2. IV winding ( kV Peak )
  3. LV winding ( kV Peak )

Stabilizing / Tertiary winding

  1. Rated voltage ( kV )
  2. Normal rating ( kVA )
  3. Normal rating ( Expressed as percent of main winding rating in case of stabilizing winding )
  4. Delta closed inside / outside ( In case of stabilizing winding )
Efficiencies at 75 oC at unity power factor
  1. At full load ( Percent )
  2. At 3/4th full load ( Percent )
  3. At 1/2th full load ( Percent )
Voltage regulation at full load at 75 oC
  1. At unity power factor ( Percent )
  2. At 0.8 power factor lagging ( Percent )
Equipment for ONAN or ONAF / ONAN cooling
State : Radiator on main bank / Separate cooler bank
State : OFAN / ODAN, ONAF, ONAN rating ( kVA ) whichever is / are applicable in case of mixed cooling
  1. OFAN / ODAN
  2. ONAF
  3. ONAN
  • Number of coolers / cooler banks per transformer
  • Rating of each cooler / cooler bank
  • OFF circuit voltage variation in case of
  1. Off circuit tap switch
  2. Off circuit links

Details of ON load tap changer

  1. Make
  2. Rating
  3. Rated voltage
  4. Rated current
  5. Step voltage
  6. Number of steps
  7. Control
  8. Auxiliary supply details
  9. Voltage control
  10. Parallel operation
  11. Protective devices
  12. Approximate overall weight ( kg )
  13. Approximate overall dimensions ( mm )
  14. Approximate overall quantity of oil ( Litre )
Terminal arrangement
  1. High voltage
  2. Intermediate voltage
  3. Low voltage
  4. Neutral

Approximate masses
  1. Core and windings ( kg )
  2. Tank , fittings and accessories ( kg )
  3. Oil ( kg )
  4. Total mass ( kg )

  • Approximate quantity of oil required for first filling ( Litres )
Approximate overall dimension
  1. Length ( mm )
  2. Breath ( mm )
  3. Height ( mm )
Despatch details
  • Approximate mass of heaviest package ( kg )
  • Approximate dimensions of largest package
  1. Length ( mm )
  2. Breath ( mm )
  3. Height ( mm )
  • Untanking height ( mm )
  • Reference standards

The following fittings should be provided.

  • Inspection cover ( Above 1600 kVA )
  • Rating plate
  • Terminal marking plate
  • Two earthing terminals
  • Lifting lugs
  • Drain valve with plug / cover plate ( 25 kVA and above )
  • Dehydrating breather ( 25 kVA and above for rated voltage 11 kV and below, and all ratings above 11 kV )
  • Oil level indicator with minimum
  • Marking
  • Thermometer pocket
  • Oil filling hole with cover
  • Conservator ( 50 kVA and above for rated voltage 11 kV and below, and all ratings above 11 kV )
  • Air release valve ( All transformers which is fitted with conservators )
  • Jacking lugs ( Above 1600 kVA )
  • Filter valve ( Above 1600 kVA )

The following types of additional fittings are provided if ordered.

  • Filter valves ( 1600 kVA and below )
  • Rollers ( If stated in the enquiry / order )
  • Thermometer ( If stated in the enquiry / order )
  • Additional thermometer pockets ( If stated in the enquiry / order )
  • Winding temperature indicator ( If stated in the enquiry / order )
  • Explosion vent ( Details to be stated )
  • Gas and oil actuated relay ( type to be stated )
  • Skids
  • Inspection cover ( 1600 kVA and below )

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