What does the term "sag" refer to in overhead lines?

The term "sag" in overhead lines specifically refers to the curve or dip of the wire caused by its weight. When a wire is suspended between two points, gravity acts on it, causing it to sag or dip in the middle section. This sag is a crucial aspect of overhead line design because it affects the overall performance, mechanical stress, and electrical properties of the wires. Proper sag ensures that the wires maintain sufficient clearance from the ground and other structures, minimizing the risk of electrical faults and ensuring safe and reliable operation.

The tension in the wire, while related, does not define sag; instead, sag is a result of that tension combined with the weight of the wire. The distance between poles and the alignment of the wires are also important considerations in overhead line construction, but they do not directly describe the phenomenon of sag itself. Understanding the concept of sag is vital for linemen and engineers when designing and maintaining overhead power lines.