1. What Is Cable Sag?

Cable sag refers to the vertical distance between the lowest point of a suspended cable and the straight line joining its supports. It is a crucial parameter in overhead power lines, telecommunication cables, and suspension bridge design.

2. How Does The Sag Calculator Work?

The calculator uses the standard sag equation:

Where:

• \( d \) — Sag in meters
• \( w \) — Weight per unit length in N/m
• \( S \) — Span length in meters
• \( H \) — Horizontal tension in Newtons

Explanation: This formula assumes a parabolic shape for the cable, which is a close approximation for most practical applications where sag is small compared to span.

3. Importance Of Sag Calculation

Details: Accurate sag calculation is essential for ensuring proper clearance above ground or obstacles, maintaining cable tension within safe limits, and preventing excessive stress on support structures.

4. Using The Calculator

Tips: Enter weight per unit length in N/m, span length in meters, and horizontal tension in Newtons. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What factors affect cable sag?
A: Sag is primarily affected by cable weight, span length, tension, temperature changes, and ice/wind loading conditions.

Q2: How does temperature affect sag?
A: Higher temperatures cause cables to expand and sag more, while lower temperatures cause contraction and reduced sag.

Q3: What is the maximum allowable sag?
A: Maximum sag depends on application requirements, typically governed by clearance regulations and structural safety factors.

Q4: Does this formula work for all cable types?
A: This formula works well for uniform cables with relatively small sag-to-span ratios. For large sags or non-uniform cables, more complex catenary equations may be needed.

Q5: How often should sag be measured in real installations?
A: Sag should be checked during installation and periodically thereafter, especially after extreme weather events or significant temperature changes.