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APPENDIX
For current information see: 1210
Appendix
Glossary
Specific volume resistance
The specific volume resistance [Ohm m] results from the measured
volume resistance [Ohm] multiplied by the measuring area [m²] divided
by the sample length [m]. VDE 0207, Part 4 and VDE 0303, Part 30.
Speed of signal propagation
Signals propagate in all cables at a speed that is always lower than the
speed of light. The NVP value specifies the ratio of this speed to the
propagation speed of light.
Spiral cable
Flexible cables that are formed into a “spiral spring”. The cable is wound
onto a mandrel. The addition of heat (tempering) reduces the tensions in
the plastic caused by the winding process, which means that the cable
retains the spiral shape in a stress free condition after cooling. When
expanded, the spiral extends and, when the force is no longer acting
upon it, returns to its original condition.
Splice
Connection of two light waveguides created by melting their ends.
Fixed connection between two light waveguides. A distinction is made
between bonded and welded splices (→ Welded light waveguide con-
nection).
Stabiliser
a) A component used in some plastics to obtain certain physical and
chemical properties during processing and the usage time.
b) Additives (e. g. lead, tin or cadmium salts) for plastics. They delay or
counteract the decomposition and aging process that occurs when
exposed to thermal loads.
Step index fibre
Light waveguide with a stepped profile, i. e. with a refraction index
profile that is characterised by a constant refraction index within the
core and a sharp decline in the refraction index at the boundary of the
core and the sheath.
STP
In twisted pair cables with foil screening of the individual pairs and an
overall braided screening (STP = Individually Screened Foil and Braid
Twisted Pair), the cores are twisted in pairs and individually screened
with a metallic foil, to achieve exceptionally low near end crosstalk.
An additional overall screen is then added.
Strain relief of cable glands
The ability of a cable gland to limit the movement of a secured cable
under a dynamic and torsional load.
Strand
The individual wires in a conductor combined into a bundle; the number
and individual wire thickness varies according to the desired cross-sec-
tion. The individual wires are either bundled by stranding or by twisting.
Individual cores, e. g. LiY, H05V-K, H07V-K
Stranding
The individual elements of cables are wound parallel around a central
element. The elements can be the individual wires in a conductor or the
cores or groups of cores themselves. Depending on requirements, the
elements are twisted or stranded with different twist lengths. This
is done in concentric layers, one on top of another, according to the
number of elements. If the subsequent layer of the element is stranded
in the same direction as the preceding layer, this is known as parallel
lay stranding, as opposed to cross lay (reversed lay) stranding, where
each subsequent layer is stranded in the opposite direction to the
previous one. The stranding has an “S” lay if the stranding direction
runs to the left as an observer looks at it, or a “Z” lay if the stranding
runs to the right: A distinction is also made between stranding tech-
niques with and without back twist.
Stranding machine, twister
Stranding machines are used to strand the components of a cable.
Different types of stranding machines include single twist, double
twist, multiple twist, high-speed, basket, SZ and universal stranding
machines.
Strip line
Strip lines are used as fixed signal transmission cables in control and
steering technology, measurement and data processing technology.
They can contain up to 40 cores which lie parallel to each as a result
of the welded insulating cover. Single cores can be separated from the
strip line, without causing any damage to the insulating cover. Their flat
arrangement means they can be guided through narrow slots or open-
ings. They are fixed in place using brackets or adhesive.
Styrol
Is used as an insulating material for telecommunication cables (→ Die-
lectric). It has a good strength value, however is not resistant to sol-
vents.
Super conduction
The property of metals and oxides to lose their electrical resistance
due to cooling when a so-called transition temperature is reached.
Supporting cable
Because of their small dimensions, they are used for installation
in small and miniature equipment.
Supporting core
Strands of hemp, steel or plastic are incorporated into the construction
as supporting elements or to absorb tensile forces. In most cases, the
carrier organ is positioned next to the core, i. e. in the middle of cables.
However, there are also constructions in which one or two steel
strands are positioned outside the bunch of cores but below a shared
outer sheath.
Surface mount base
Lower housing sections with an enclosed base are referred to as sur-
face-mounted. Surface mounted bases are available with a cable outlet
on the right-hand side or on both sides of the housing.
Synthetic india rubber
Butyl synthetic rubber has a high resistance to ageing and lower gas
permeability. It is highly resistant to chemicals.
T
T-Coupler
Optical component for combining the light from two light waveguides
(see also → Coupler). Conversely, it can also be used to split the light
output in one light waveguide into two outgoing light waveguides.
Take-up system
Sheathed cables are generally wrapped around wooden or process
drums. The most common types of winding devices are bottom roller