If the sag of transmission line increases, tension _____

Concept:

Sag is defined as the difference in level between points of supports and the lowest point on the conductor.

Sag of conductor’s between two poles can be determined by

Where, S is the sag of conductors

W is the weight per unit length of the conductor

L is the length of span

T is the tension in the conductor

Factors affecting the sag:

Conductor weight: Sag of the conductor is directly proportional to its weight. The weight of the conductors is increased due to ice loading.

Span: Sag is directly proportional to the square of the span length. Longer span gives more sag.

Tension: The sag is inversely proportional to the tension in the conductor. Higher tension increases the stress in the insulators and supporting structures.

Wind: It increases sag in the inclined direction.

Temperature: The sag is reduced at low temperatures and is increases at higher temperatures. In summer due to the increase in average temperature tension decreases and hence sag increases comparison to winter.

The sag of the transmission line is least affected by current passes through the conductor.