Cathodic protection cables
Additional equipment of cathodic protection systems / cathodic protection cables:
The cables used in the cathodic protection system are usually single-strand semi-transparent (7 strands) with facing covers; XLPE/PVC, HMWPE/PVDF, EPR
Design documents and environmental conditions determine the type of cable covering and its size. In cathodic protection systems, cross-linked polyethylene cable with PVC coating (XPLE/PVC) according to IEC60502 and ISIRI3569 standard and copper conductor standard IEC60228 and ISIRI3084 are used. The amount of current passing through the cable determines its size (according to the IEC standard, the permissible voltage of the rectifier transformer is 50 volts. Therefore, in addition to the passing current, the length of the cable is also effective in choosing its size). According to the common standards of the cathodic protection system, it should be avoided to use joints in the main cable path. During the execution and installation of the cable, damage to the cable cover should be avoided, this will cause the cable to break over time.
Armor is used to prevent damage to the cables. Cables are made in two types of aluminum armor “A” and steel “S”. Cable with steel armor is not used in AC single-core cables. Armored cables can be used underground, inside a duct, covered, etc.
Usually, HMWPE/PVDF coated cable is used in chemical and chlorine environments such as: well anode bed, tank bottom anode network, etc.
The HMWPE coating of these cables is very favorable in terms of electrical insulation and has a high resistance to moisture. At the same time, they are resistant to chemicals, organic and mineral substances. The coating of this type of cables has a high strength to withstand tension and impact during execution. PVDF coating of this type of cable is a very resistant thermoplastic type and has many properties. This coating has very favorable stability against chemical and temperature changes like fluoropolymers. This feature is due to the use of CH2 and CF2 in its compositions. The following are the properties of PVDF coating:
High mechanical strength, abrasion resistance, high thermal strength, resistance to most solvents and chemicals, resistance to ultraviolet rays, resistance to air, low permeability to gases and liquids, resistance to fire and burns.
Cables that are exposed to sunlight or high temperature are usually selected with EPR coating. The cover of this type of cables is made of propylene ethylene with rubber properties that are highly resistant to moisture, temperature, direct sunlight, etc. Cables with EPR coating are also used underwater. Among the advantages of this type of cable covering, the following can be mentioned:
Can be installed in ambient temperature up to 105 degrees Celsius, resistance to heat and moisture, resistance to flame, resistance to direct sunlight, flexibility and easy transportation, high electrical insulation, low moisture absorption, resistant to chemicals. Bending ability at ambient temperature up to -35 degrees Celsius
The effect of temperature on the resistance of the cable is calculated from the following tables and formulas according to the alternating and directness of the resistance:
How to install the cable
a) First, dig a trench with a width of 30 cm and a depth of 70 cm, then sand the first 10 cm of the trench floor and install the desired cables inside the trench.
b) Backfill with sand up to 15 cm above the installed cables.
c) Place pressure bricks or cement blocks on the cable path inside the trench, then install the danger strip inside the trench and at the end, backfill the trench with the soil obtained from the excavation up to the ground level.
Ground cable implementation plan
