Before installing overhead lines certain condition should be fullfilled to incrase the life of a line most important conditions are
1.Tension should be less
2.Their should be a proper sag
Both of these conditions should be fullfilled before installing the line failure of any conditions means line breakdown
Our desire is less heigh poles and less sag but it is very dangerous b/c in winters contraction will happen between lines if their is no proper sag so line will breaks
Demerits of Loose Sag
1. Height of tower will be increased
2.cost of tower and material of conductor will be increased
3.size of conductor will also be increase
4.Weight of conductor will also be increased
Minimum ground clearnce for sag
The minimum space requied for a safe operation of electric supply between ground and conductor is known as ground clearnce
Every country has its own standards in pakistan the minimum ground clerance for 33kv is 20 feet
33kv=20 feet
Then after every 33kv increase in voltage 1 feet will be increased
66kv=21feet
Calculations of sag
For equal supports
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