What temperature should a cable be rated for?

Cables should be suitable for all environmental conditions that occur in the areas where they are installed (see ICEA and NEMA standards on cable for information concerning cable ratings). Cable operating temperatures in substations are normally based on 40 °C ambient air or 20 °C ambient earth.

What is a good resistivity value for a low-grade cable?

When the earth resistivity is not known, a value of 90 °C cm/W is suggested in IEEE Std 835. The ampacity of below-grade cable is also dependent upon the load factor, which is the ratio of the average current over a designated period of time to the peak current occurring in that period.

How is a substation cable guide organized?

The main clauses of the guide are organized by cable type and each of these clauses has been organized to match the general steps involved in the design process for a substation cable system (see Annex A for a flowchart diagram). Common information for each type of cable is placed in the annexes and is referenced from the body of the guide.

Should a cable be stored inside?

It is preferable to store the cable inside if UV protection cannot be provided. If the cable manufacturer’s recommended maximum pulling tension, sidewall pressure, or the minimum bending or training radius is violated, damage could occur to the cable conductor, insulation, shield, or jacket.

What type of cable is used in this example installation?

The cable to be used in this example installation is 3-1/c 750 kcmil triplexed aluminum cable with 1/3 concentric neutral. The completed weight of this cable is 78.4 N/m (5.375 lb/ft) and the OD for each cable is 4.09 cm (1.61 in). Plastic conduit suitable for direct burial (Type DB) is to be used for this example installation.

Where should a medium-voltage power cable be installed?

Installation of medium-voltage cables in raceways that are separated from low-voltage power and control cables and from instrumentation cables. Installation of different voltage classes of medium-voltage power cables in separate raceways is also recommended.