Cable tensile force calculations in the project planning phase

Calculations for cable tension and pressure in the project planning stage

An accurate estimate of cable tensile forces is crucial for the optimal design of high-voltage cable systems. Knowledge of these forces helps to avoid both underestimated and overcautious planning approaches, which can lead to considerable cost savings during construction.

Early planning in the project phase enables options for cable dimensioning and laying that may not be feasible later in the construction preparation phase.

New high-voltage cable routes for infrastructure projects are sometimes hundreds of meters long, and the cables need to be pulled in when they are laid in a trench, duct system or open trench – a process that can damage the cable or the duct in which it is laid. Through detailed cable pulling calculations, Bynoc’s engineering team can help avoid costly and time-consuming delays that could affect the entire project.

It is therefore essential to obtain detailed information from the customer in advance to ensure accurate planning and avoid potential problems, including

• Cable design (conductor design, outer sheath diameter, cable weight)
• Minimum bending radius of the cable
• Permissible tension on the cable pulling head device and the conductor
• Permissible side wall pressure
• Channel type with dimensions
• Details of the cable route layout (joint positions, open trench/duct and HDD/micro-tunneling sections, if available)
• Longitudinal profiles of the cable route (with relevant information on straight sections, horizontal/vertical bending radii, bending angles, inclination directions, etc.). )

A point-by-point calculation method is performed at each line bend and pull point (x, y, z) along the entire length of the cable section, taking into account an appropriate coefficient of friction (COF) between the cable and the surface. Both the forward and reverse tensile forces are calculated to determine the preferred direction of pull.

If the calculated cable pulling force exceeds the maximum permissible value specified by the cable manufacturer, we can use a cable slider (e.g. at the insertion/starting point of the installation through pipe segments) to support the cable pull and at the same time reduce the pulling forces.

A comprehensive cable tension calculation is essential before finalizing the cable route!