Cable Sizing and Schedule

Cables play an integral role in every electrical system and are used in all the three major phases of a power system – generation, transmission, and distribution. The process of selecting the most appropriate size of cables based on the requirements of the system is called cable sizing. The size of a cable is specified in terms of its cross-section area.
The purpose of calculating cable sizes is to figure out if the cable can transmit current and voltage continuously to all the loads. Another vital thing to consider is if the cable can handle short circuits and voltage drops. Before calculating the size of the cables, the following information must be collected:

  • Specifications of the cable
  • Specifications of the loads that are connected to the cable
  • The method of cable installation

Process of Cable Sizing

The entire process of cable sizing involves three main steps.

Why Is It Important To Conduct Arc Flash Studies?

Step 1: Data Collection

Three main categories of data must be collected for cable sizing, as mentioned above.
1. Cable specifications, such as type of conductor (bared, insulated), the type of insulation, the number of cores, and length of the cable based on the distance between the loads and the power source.
2.Load specifications, such as voltage, current, and power ratings.
3.Method of installation (underground, overhead, etc.), which also includes factors such as the spacing between the grouped cables and so on.

Step 2: Calculation

Using the above data, calculations are made based on different factors such as current flow in the cable, voltage drops, short circuits, and temperature changes due to external conditions or due to heat generation caused by resistive and dielectric loss.

Step 3: Size Selection

The most appropriate size of the cable is determined according to the results of the above calculations.

Our Services In Cable Sizing And Schedule

We perform extensive cable sizing calculations to provide highly accurate results. We have an expertise on IEC 60364 and 60287 and are capable of sizing of LV and HV. We can also calculate the armor circuit current and end line armor standing voltage to ensure these values are within the limit.
Contact us today to learn more.