1. To size 1 no. Soak pit for 4 nos. GTs of capacity 50 MVA each. 2. To size one no. Soak pit for 1 GT of capacity 50 MVA and 2 Power Transformers of capacity 31 MVA each.
2.0.0
To size one no. Soak pit for 2 Tie Transformers of capacity 37.5MVA each.
CONSIDERATIONS 3 nos. soak pits have been considered in the transformer yard. The capacity of each soak pit is calculated taking the largest transformer oil capacity.
3.0.0
DESIGN DATA Soak pit 1 (Located on the western side of s/s28 Building): Rating of Generator transformer is assumed as follows: •
Rating : 50 MVA
•
Oil capacity: 18000 litres….( As per BHEL Recommendation )
Soak pit 2 (Located on the Eastern side of s/s28 Building): Rating of Generator transformer is assumed as follows: •
Rating : 50 MVA
•
Oil capacity : 18000 litres….( As per BHEL Recommendation )
Rating of Power Transformer is assumed as follows: •
Rating : 31 MVA
•
Oil capacity: 12500 litres ….( As per BHEL Recommendation )
Soak pit 3 (to be located near the tie Tie Trafo yard suitably): Rating of Tie transformer is assumed as follows:
4.0.0
•
Rating : 37.5 MVA
•
Oil capacity : 29000 litres….( As per BHEL Recommendation )
DESIGN CRITERIA •
Soak pit volume shall be 125 % of the oil volume of the largest transformer.
= 22500 litres If the drain pipe (150-mm dia.) from the transformer’s individual oil pits are to be connected to the soak pit with a slope of 1 in 100. H1
= 0.15 + (1/100)*50, where 50 is the distance of soak pit from the transformer oil pit = 0.65 metre
For a volume of 22.5 cubic meter, assuming length as 4.5 m and breadth as 3.5 m H2
= 22.5/(4.5 *3.5) = 1.43 metre.
Total height of soak pit
= H 1 + H2 = 0.65 + 1.43 = 2.08 metre
Dimension of Soak pit 1 (L * B * H) is 4.5m * 3.5m * 2.08 m Soak pit 2: Soak pit volume
= 1.25 * 18000
H2
= 22500 litres If the drain pipe (150-mm dia.) from the transformer’s individual oil pits are to be connected to the soak pit with a slope of 1 in 100. H1
= 0.15 + (1/100)*50, where 50 is the distance of soak pit from the transformer oil pit
