12kv Power Mounted Transformer

Product Description

Clause      Description      SPECIFICAITON

1.      Scope

1.1.            Supply of        i.       hermetically sealed oil-immersed distribution transformers

1.2.                                   ii.      for continuous service on 11kV, 3 phase, 50Hz system

1.3.                                 iii.               suitable for the following climatic conditions:

1.4.                    

                                    a.      Ambient shade temperature:  5 °C – 45°C

1.5.                              b.      Relative humidity:          50% – 95%

1.6.                              c.      Atmosphere:    Heavily polluted and saline

1.7.                           iv.      suitable for Installation:          Outdoor – Pole mounted

1.8.              General Transformer Requirements

1.8.1.                  Standard  Latest editions of IEC 60076

1.8.2.                  Type of transformer         Three phase with separate primary and secondary windings

1.8.3.                  Rating       250kVA (See Section 4 ‘Technical Specifications’/ Part 2 ‘Information and       Documentation’ – Form 1 – ‘Schedule of Guaranteed Technical Particulars’)

1.8.4.                  Insulating oil    i.       filled with uninhibited transformer oil

1.8.5.                                           ii.      to IEC60296

1.8.6.                  Type of cooling:      ONAN

1.9.            Rated Voltages

1.9.1.                  HV   11kV

1.9.2.                  LV ( On normal tap and no load )    Single voltage: 400V (See Section 4 ‘Technical Specifications’/ Part 2 ‘Information and Documentation’ – Form 1 – ‘Schedule of Guaranteed Technical Particulars)

1.10.                   Tap changer

1.10.1.               Type        Off-circuit

1.10.2.               Tapping range          +5%, –5%

1.10.3.               Tapping step   2.5%

1.11.                   System highest voltage

1.11.1.               HV   12kV

1.11.2.               LV    1.1kV

1.12.                   System earthing

1.12.1.               HV   Resistance

1.12.2.               LV    Solid

1.13.                   Insulation level for HV winding

1.13.1.               Rated short duration power frequency withstand        28kV r.m.s

1.13.2.               Rated lightning impulse withstand voltage          75kV peak

1.14.                   Insulation level for LV winding

1.14.1.               Rated short duration power frequency withstand        3kV

1.15.                   Connection symbol Dyn11

1.16.                   Impedance Voltage at principal tap and winding temperature of 75°C

1.16.1.               250kVA    (applies for this tender) 3.75 to 4.25%

1.16.2.               500kVA    (not applicable for this tender)         3.75 to 4.25 %

1.16.3.               800kVA    (not applicable for this tender)         4.25 to 4.75%

1.16.4.               1000kVA  (not applicable for this tender)         4.75 to 5.25%

1.16.5.               1600kVA  (not applicable for this tender)         6.00 to 6.50 %

1.17.                   Maximum sound pressure level Lp at 0.3 m          55dB(A)

1.18.                  Maximum overall dimensions

1.18.1.               Width      1200mm

1.18.2.               Height     1400mm

2.      Windings

2.1.            The primary and secondary windings must consist of high conductivity copper  wound on formers to produce coils. 

2.2.            [Aluminium windings, if offered, shall be deemed NOT Compliant]

2.3.            For the purpose of voltage control, tappings must be provided on the higher voltage windings of all the transformers to give a transformation variation range of plus 5% and minus 5% in 2.5% steps. 

2.4.            i.       The off-circuit tap selector switches must be operated by hand wheel external to and on one side of the transformer tank.