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II. TRANSFORMER (OIL - TYPE)

1. Scope

This section covers the detailed requirements regarding supply of transformer required for the sub-station.

2. GENERAL CONSTRUCTION

a. The transformer shall comply with the following Indian Standards as amended upto date :

1. IS 2026 - Part I to V power Transformers.

2. IS 335 - Transformer oil.

3. IS 1886 - Installation and Maintenance of Transformers.

4. IS 2099 - Bushings.

5. IS 2705 - Current Transformers.

6. IS 6600 - Guide for loading of oil immersed Transformers.

b. Tanks and Radiators

Tanks shall be of MS plates and structurals, electrically welded. The construction shall be robust and substantial, suitable for road/rail transport and to withstand vibration. Radiator tubes shall be electrical resistance welded type, round or elliptical or rectangular. They may be welded to the transformer tank or in case of very large sizes to separate detachable radiator banks connected through intermediate leak proof valves. Detachable radiator banks shall have top and bottom headers with flanged connections, with drain and vent fittings. Tanks shall be provided with lifting lugs and jacking lugs. Inspection hole with cover should also be provided for large transformers. Oil conservators shall be mounted on brackets attached to the top cover on tank. Dimensions of the conservator shall be such as to allow change in volume of oil due to change in temperature from 10o C to 95o C.

Tanks shall be thoroughly cleaned, degreased and sand blasted inside and outside. A coat of rust resisting primer shall immediately be given on outside surface. Inside surface shall be painted with oil resistance enamel paint. Tank and radiators shall be hydraulically pressure tested. Tanks shall also be tested for full vacuum. The procedure for testing shall be as follows :

i. Vacuum Test

The tanks designed for all vacuum shall...