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Wire & Cable ASIA – January/February 12
The main focus of UL 4703 is the fire performance. Tests to
be performed are the Vertical Flame Test acc. to UL 1581,
Section 1060 or optional flame test VW-1 acc. to UL 1581,
Section 1080. Based on RHW-2 the flame test FT-2 acc. to
UL 1581, Section 1100 is also required.
Table 2
compares some important parameters and
tests of both standards against each other. Therefore,
another cable construction will be necessary to meet the
UL-requirements.
6 Product Properties
The newly developed solar cable is a
single core cable built with a tinned
stranded conductor.
All materials are halogen free, flame
resistant and fire retardant. No corrosive
gases will be released in case of fire and
the smoke density is low. The insulation
and jacket materials are extremely
resistant to weathering, UV-radiation and
abrasion.
The wide temperature range from -50°C
to +150°C (fixed installation) enables
the use of this cable in extreme weather
conditions. Additionally, it is salt water
resistant and resistant to acids and
alkaline solutions.
The cable is flexible and designed for
high mechanical loads. So it is suitable
for fixed installation as well as for moving
applications without tensile load.
❍
❍
Figure 5
: The developed cable in different cross-sections
❍
❍
Figure 4
: Long term thermal test results
Arrhenius Lutze Thermoflex Solar
Hours
Temperature in ºC
It is especially designed for outdoor use, which means
direct sun radiation and air humidity, but due to the
halogen free flame retardant cross-linked jacket material
the cable can also be installed in dry and humid conditions
indoors.
A product life cycle of 25 years can be expected for this
solar cable. Insulation and jacket are easily removable.
All materials used in the cable are in conformance to
European RoHS-directive.
There are two versions available signed by ink-jet printing
for positive and negative polarity.
The dimension range is from 2.5mm
2
(overall diameter
4.5mm) up to 35mm
2
(overall diameter 11.0mm), other
cross sections are available upon request.
The described solar cable is named Lütze Thermoflex
Solar XPE. It has passed all the described tests and was
certified by the VDE testing and certification institute
according to the discussed specification
[2]
.
It is registered at VDE by Reg-No 8293. Another solar
cable type using AWG conductor sizes has been
developed according to UL 4703
[3]
and is currently/actually
in the certification process.
7 Conclusions
There are different standards for solar cables in different
countries. The requirements are very high, but they
differ due to the various national philosophies in respect
to safety and reliability issues as well as market and
subvention aspects.
The determining factors in this application are external
conditions, which do not depend on national laws and
can depend only on local aspects.
Therefore, a standard in the future will be established by
international market acceptance.