Electricity + Control October 2016

CABLES + ACCESSORIES

• The lifespan of PV cables is generally 25 years. • Continuous direct sunlight exposure causes cables to degrade. • Protection of cables from direct sunlight can be achieved by implementing a code compliant wire management system.

take note

unless the cable or its protective sheathing are adequately shielded or of a special design to withstand the effects of such exposure.

technologies in the market are: ♦ Heyco’s SunScreener ♦ Spiffy’s Solar screening

Protection of cables from physical damage TUV approved PV cables are manufactured with mechanical robust- ness. These solar cable are insulated twice with an insulation around the conductor and an insulation outer jacket. If the outer jacket is dam- aged or cut, there is another layer providing the necessary protection for the conductor. The insulation for PV cables is also manufactured by using the electronic beam cross linking procedure which improves the shear and impact strength of the cable thus protecting the cable more effectively. Notwithstanding the above, damage can still occur during PV cable installation if sharp edges and corners exist. Moreover, PV cables are installed through openings drilled in the structural metal work of the PV system creating sharp holes that can cut through the insulation of the cable. PV cables and their insulation shall be protected by ensuring that every hole is bushed so as to prevent abrasion of the cable insulation or even compressed under the weight of modules. PV cables must be protected from possible movement by the fastening of cable ties, clips and other attachment tools ensuring that the electrical properties of the cables is not in any way compromised. Protection of PV cables against corrosion The insulation for PV cables is manufactured by using the electronic beam cross linking procedure. These cross linked insulation materials greatly improve the chemical resistance of the cable thus protecting the cable more effectively. The type of PV cable insulation must be selected to be able to protect the cable from corrosive chemicals. The protection of PV cable can be provided by fixing the cable in positions where the cable or its protective insulation is adequately shielded or exposed to corrosive chemicals or as mentioned, of special design to withstand the effects of such exposure. PV cables that are likely to be exposed to chemicals should have an insulation cover that has a high degree of resistance to chemicals. The PV cables can be afforded protection by being kept or shall not be fixed within six inches from such corrosive materials the con- tents of which might damage the cable or its insulation unless the cable is adequately shielded or of a special design to withstand the effects of such chemicals. Protection of cables from animals Pests like rodents feed on PV cables resulting in a loss of production and extensive repair works if the issue is not addressed. Some of the existing technology on the market to mitigate this situation involves the use of barriers attached to structural members and rails. The two

Conclusion It can be noted that compliance with the relevant standards will certainly achieve the code compliant and safe cable management for PV cables. As a result of adhering to the design and installation requirements, the entire PV cabling network can be adequately pro- tected. The PV cable system will ensure reliability guaranteeing the much required rate of return on the capital investment for clients. maintenance of the installed system must follow to ensure that the investment does not deteriorate and this can be achieved by peri- odic inspections and verification of the soundness of all PV cables and equipment. The maintenance can be achieved by drawing up a maintenance management plan which can be agreed with the clients. With the evolving of new technologies, installers must advise clients on these new innovations and be able to advise on ways to improving the old existing plants. Factors for consideration in selecting the right technology for protection of the PV cables should be based on code compliance, ease of installation and cost. References [1] ISO 4892-1. 2016. Plastics -- Methods of exposure to laboratory light sources. Part 1: General guidance. [2] EN 50395:2005. 2011. Electrical test methods for low voltage energy cables. [3] EN 50396:2005: 2011. Non electrical test methods for low voltage energy cables. [4] IEC 60811:2012. Electric and optical fibre cables - Test methods for non-metallic materials.

Morgan Havire is a Chartered Electrical Engineer with experi- ence that includes site surveys, design, supervision, testing and commissioning of new buildings and refurbishment of existing ones. He has undertaken major projects as a principal and lead design engineer responsible for all electrical and electronic services on projects in South Africa, Zimbabwe,

Angola, Mozambique, Zambia and Equatorial Guinea. Morgan has undertaken design assignments within teams working on projects in South Africa, Zambia, Mozambique, Nigeria, Australia, United States, Nigeria and Equatorial Guinea. Morgan has experience in sustainable building design concepts that include photo voltaic solar power on projects. Enquiries: Email mhavire@gmail.com

Electricity+Control October ‘16

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