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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).
The first in a series of articles on cable protection.
Morgan Havire, AMNS Consulting Engineers
CABLES + ACCESSORIES
Factors that influence
cable
protection
Electricity+Control
October ‘16
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