The transformers shall be suitable for continuous operation on a 3 phase, 50 Hz electrical power distribution system with neutral earthing conditions and maximum phase fault levels as follows :-
11 Kv 350 MVA
6.6 Kv 150 MVA
3.3 Kv 75 MVA
415 V 31 MVA
They shall be fully tropicalised and suitable for continuous operation at an ambient temperature up to 40 degree Celsius, relative humidity up to 100%,isoceraunic level up to 200 days per annum and altitude up to 1000 metres above sea level.
4.1 TYPE OF TRANSFORMER
The transformers shall be oil-immersed naturally cooled and hermetically sealed type complying with BS 171 or IEC 76 and suitable for indoor duties. Unless otherwise specified, they shall be low loss, step-down type of distribution transformers fitted with skid type bases.