Electricity + Control October 2016

CABLES + ACCESSORIES

Factors that influence cable protection

Morgan Havire, AMNS Consulting Engineers

The first in a series of articles on cable protection.

T he principle of generating electricity through the conversion of the naturally abundant sun rays by solar cells is termed Pho- tovoltaic. Solar cells located inside solar panels using special semi-conductor materials are capable of harnessing the solar energy producing the much needed electricity. The electricity produced by the solar panels is termed direct cur- rent (dc) is transported through a system of cables to either storage rechargeable battery systems or onto the electricity grid as alternating current (ac) for use. The system of cables used for the transmission of electricity are typically outdoor and are subjected to the harsh environmental fac- tors which means that they require protection to guarantee proper functioning over a prolonged period and safety. In order to adequately address the issues surrounding the protec- tion of cables, we need to take cognisance of factors that affect cables and from these factors we can deduce the various and most humanly possible ways in which these can be mitigated. The factors that affect cables can be categorised into ‘Thermal’ and ‘External Influences’. External influences: Any influences that are external to the cables which can affect the safe operation of the cable and also the design. These include factors such as: ♦ Ambient temperature - temperature of air or any other medium where the cables are installed ♦ Direct sunlight ♦ Animals and plants ♦ Rain or water vapour or water accumulation ♦ Chemicals ♦ Mechanical damage Thermal effects: Thermal effects arise due to the operating condi- tions of cables such as: ♦ Voltage ♦ Method of installation ♦ Cable grouping ♦ Protective measures ♦ Current, and accessibility Additional thermal effects could be due to over-current (overloads and short circuits).

Electricity+Control October ‘16

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